Geomorphology and Plate Tectonics [1 ed.] 9781616689971, 9781607410034

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Copyright © 2009. Nova Science Publishers, Incorporated. All rights reserved. Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers, Incorporated,

Copyright © 2009. Nova Science Publishers, Incorporated. All rights reserved. Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers, Incorporated,

Copyright © 2009. Nova Science Publishers, Incorporated. All rights reserved.

GEOMORPHOLOGY AND PLATE TECTONICS

No part of this digital document may be reproduced, stored in a retrieval system or transmitted in any form or by any means. The publisher has taken reasonable care in the preparation of this digital document, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained herein. This digital document is sold with the clear understanding that the publisher is not engaged in Guiseppi, Antonio R..rendering Geomorphology Plate Tectonics, edited professional by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers, legal,and medical or any other services.

Copyright © 2009. Nova Science Publishers, Incorporated. All rights reserved. Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

GEOMORPHOLOGY AND PLATE TECTONICS

DAVID M. FERRARI AND

ANTONIO R. GUISEPPI Copyright © 2009. Nova Science Publishers, Incorporated. All rights reserved.

EDITORS

Nova Science Publishers, Inc. New York

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Copyright © 2009 by Nova Science Publishers, Inc. All rights reserved. No part of this book may be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic, tape, mechanical photocopying, recording or otherwise without the written permission of the Publisher. For permission to use material from this book please contact us: Telephone 631-231-7269; Fax 631-231-8175 Web Site: http://www.novapublishers.com NOTICE TO THE READER The Publisher has taken reasonable care in the preparation of this book, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained in this book. The Publisher shall not be liable for any special, consequential, or exemplary damages resulting, in whole or in part, from the readers’ use of, or reliance upon, this material.

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Independent verification should be sought for any data, advice or recommendations contained in this book. In addition, no responsibility is assumed by the publisher for any injury and/or damage to persons or property arising from any methods, products, instructions, ideas or otherwise contained in this publication. This publication is designed to provide accurate and authoritative information with regard to the subject matter covered herein. It is sold with the clear understanding that the Publisher is not engaged in rendering legal or any other professional services. If legal or any other expert assistance is required, the services of a competent person should be sought. FROM A DECLARATION OF PARTICIPANTS JOINTLY ADOPTED BY A COMMITTEE OF THE AMERICAN BAR ASSOCIATION AND A COMMITTEE OF PUBLISHERS. LIBRARY OF CONGRESS CATALOGING-IN-PUBLICATION DATA Geomorphology and plate tectonics / Editor, David M. Ferrari and Antonio R. Guiseppi. xiv, 398 p. : ill., maps (some col.) ; 26 cm. Includes bibliographical references and index. ISBN: H%RRN 1. Geomorphology. 2.Landforms. 3.Plate tectonics. I. Ferrari, David M. and Guiseppi, Antonio, R. GB401.5 .G4537 2009 551.41 2009030977

Published by Nova Science Publishers, Inc. †New York

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

CONTENTS Preface Chapter 1

Cosmogenic Nuclides and Geomorphology: Theory, Limitations, and Applications Yingkui Li and Jon Harbor

1

Chapter 2

Flood Risk and Landform of Cambodian Mekong Delta Shigeko Haruyama and Takeshi Ito

Chapter 3

Why Are Rock Glaciers More or Less Prominent in High Mountains? Sébastien Monnier

55

On Shaky Ground: Arctic Communities in Uneasy Transition to a New Climatic Order Mary J. Thornbush and Oleg Golubchikov

85

Geomorphic Adjustment, Geographic Context, and Disturbances Jordan A. Clayton

97

Chapter 4

Chapter 5 Copyright © 2009. Nova Science Publishers, Incorporated. All rights reserved.

vii

Chapter 6

Chapter 7

Chapter 8

Chapter 9

Erosion and Sediment Yield Estimated by GeoWEPP for Check Dam Watersheds in Ephemeral Gullies (South-East Spain) R. García-Lorenzo and C. Conesa-García

35

117

Modelling the Potential Impact of Groundwater Dynamics on Gully Erosion and Drainage Basin Evolution S. Pelacani , M. Märker and G. Rodolfi

141

Paleomagnetic Evidence for Siberian Plate Tectonics from Rodinia through Pangaea to Eurasia D.V. Metelkin, A.Yu. Kazansky and V.A. Vernikovsky

159

Geodynamics of Indian Free-Board: Archean-Proterozoic Collision Zones and Underlying Lithosphere and Its Rapid Drift D.C. Mishra and M. Ravi Kumar

237

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Contents

vi Chapter 10

Chapter 11

Nature of Permian Faunas in Western North America: A Key to the Understanding of the History of Allochthonous Terranes Calvin H. Stevens and Paul Belasky Geodynamic Evolution of the North African Atlasic Belt Missoum Herkat

275 311

Short Communications A

B

C

3D Morphology of Phase Microscopic Objects by the Digital Holographic Interference Microscopy Method T.V. Tishko, D.N. Tishko and V.P. Titar Tectonic Control on the Evolution of the Middle Triassic Platforms in the Alpine-Carpathian-Dinaric Region (Differences in the Evolution of Two Opposite Shelves of the Neotethys Ocean) Felicitász Velledits Morphostructure Peculiarities of Pay Zones at the Continental Margins of the North-West Australia A. Zabanbark

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Index

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

345

359

377 383

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PREFACE Geomorphology is the scientific study of landforms and the processes that shape them whereas plate tectonics specifically describes the large scale motions of Earth's lithosphere. This new book presents theory, methodology and applications, as well as studies of specific geographic regions. A model to evaluate the effect of groundwater fluctuations on the development of gullies and hence, on landscape evolution is analyzed. The use of cosmogenic nuclides in geomorphology and earth-surface processes is also reviewed and uncertainties and limitations related to current understanding of the physical properties of cosmogenic nuclides are summarized. In addition, this book studies plate tectonics in several regions of the world, including Siberia, Western North America, North Africa, India, and Northwest Australia. Chapter 1 - Since the mid 1980s, the use of in-situ-produced cosmogenic nuclide techniques has allowed rapid progress and unique advances in a wide range of areas in geomorphology and Earth-surface processes. Cosmogenic nuclides are produced by the interaction of cosmic rays with minerals at or near the Earth’s surface, and measurements of single or multiple nuclides in rocks or sediments can be used both as chronometers for surface exposure or burial time, and to unravel temporal and spatial variations in the rates and styles of geomorphic processes. As dating tools, cosmogenic nuclide approaches can be used over a wide range of timescales (103 – 106 years) and with a wide range of materials, providing unique opportunities to resolve issues that were previously unsolvable because of a lack of suitable materials and/or limited timescales for other dating methods. As a way to quantify geomorphic process rates and landscape evolution, cosmogenic nuclide techniques have been used to determine erosion, weathering, accumulation, and soil formation rates at landform and landscape scales. This has allowed reassessment of many traditional opinions, hypothesis, and models in geomorphology and Earth-surface processes, and development of updated ideas based on new abilities to examine processes and landscape evolution. In this paper, we review the use of cosmogenic nuclides in geomorphology and Earth-surface processes, summarize uncertainties and limitations related to current understanding of the physical properties of cosmogenic nuclides, as well as sampling and measurement, and examine applications of cosmogenic nuclide techniques to various areas of geomorphology and Earth-surface processes, including glacial chronology and geomorphology, geomorphic process rates, tectonic geomorphology, and landscape evolution. Chapter 2 - Flood risk zoning based on geomorphology for disaster mitigation is supporting the important fundamental knowledge for the regional disaster prevention work and urban-rural planning, that could help to reduce flooding damage and a number of victims

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

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viii

David M. Ferrari and Antonio R. Guiseppi

of disaster. In the authors purpose of this study, the first one is accounting for the relationships between geomorphologic structures and flood dynamics explained for their special state and their changes of flood characteristics under the control of human activities, the other one is rendering the accurate mapping method explicit using satellite remote sensing technology for the specific flat landform landscape of the Mekong River delta in Cambodian territory. To examine the recent flooding dynamics of the Cambodian Mekong delta, geomorphologic land classification map showing flood types of the fluvial plain was prepared for discussion with flooding states and their transition in terms of time. The flooding extension mapping in time and space, was conducted to be adopted by the NRCS (Normalized Radar Cross Section) values which were given by numerical value series provided by JERS-1 SAR satellite imagery in monsoon season. In the results of the authors study, flood dynamics superintend the geomorphologic structures, such as inundation periods, inundation depths and flood flow direction on the Cambodian Mekong River delta. The authors To judge from the final result, -3.2dB is the most appropriate value for flood mapping of JERS-1 SAR. The chief distinction of flooding distribution of the monotone delta was elucidated that the scattered back swamps behind natural levee which is trend deep inundation, make apparent for high flood vulnerability as for the deepest and longest inundation period. On the other hand, alluvial terrace formed in Holocene and natural levee are showing trivial flooding than back swamp disputed geomorphologic structure. Chapter 3 - In this chapter, the spatial prominence of rock glaciers is analyzed from two study areas, the Vanoise Massif, Northern French Alps, and the Chandi-Gorakh Himal, Western Nepal. Data are collected using public remote sensing techniques (PhotoExploreur© and Google EarthTM). In the Vanoise Massif, a spatial unit-based method is performed in order to differentiate units with rock glaciers and units without rock glaciers. In the ChandiGorakh Himal, the distribution of the rock glaciers is confronted to the distribution of other phenomena through GIS operations. This chapter emphasizes on the influence of glacier occupation and topography on rock glacier occurrence and prominence. Rock glaciers are highlighted as post-glacial features. Chapter 4 - Much attention has recently been given to the Arctic within a context of climate change. Its high latitude has made the Arctic one of the most sensitive regions on Earth, conveying landscape modifications in a warming world. This chapter examines the evidence of landscape change from a combined geomorphologic and socio-political approach by considering permafrost and thermokarst development, issues around the opening of the region (i.e. the Northwest Passage in Canada), as well as varied implications on local communities, international affairs, and geopolitics. The consideration of these issues is based on the assumption that climatic warming is changing the Arctic landscape and that northern regions will be a focal point in the search for resources. Chapter 5 - The adjustment of natural landscapes relates to the interaction between the rate, magnitude, and continuity of the various agents of change, and the resistance of earth systems to alteration in the past and present. Three general categories encompass the nature of these interactions: continual (e.g. gravity-driven) adjustment, uniformitarian systems (those subjected to periodic pulses of adjustment), and disturbance-dominated systems (wherein singular events leave a lasting footprint on the landscape) (Schumm, 1988). Previous models of geomorphic change have tended to focus on uniformitarian systems using a quantitative approach (e.g. Wolman and Miller, 1960). This paper outlines some deficiencies of quantitative, uniformitarian models, and introduces a qualitative method, the “disturbance

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

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Preface

ix

geomorphology model”, to treat landscape adjustment in the context of the continuum presented above. Several case studies of geomorphic adjustment are given as examples of the disturbance geomorphology approach. Finally, the auhtors argue that reconciliation between qualitative and quantitative models is possible when qualitative models are used as the theoretical framework within which specific, quantitative analyses can be based; while predictive capability is a product of the quantitative aspects of the study, geographic and temporal context is provided by an appropriate qualitative conceptualization of the problem, such as the disturbance geomorphology model discussed herein. Chapter 6 - The WEPP predictive erosion model has been validated for check dam watersheds in Mediterranean ephemeral gullies, in particular for two catchments with semiarid environments representative of the South-East of Spain. By means of its geospatial interface GeoWEPP, implemented around ArcView, rates of soil loss and sediment yield were obtained which were compared to the values for volume and mass of the sedimentary wedges of the check dams. Detailed information as to slope processes compiled in these subcatchments, as well as the geometry of the wedges and the physical characteristics of the material retained by the check dams have allowed the quality of the theoretical estimations of this model to be determined. The GeoWEPP simulation was carried out for isolated rainfall events using the Watershed and Flowpath methods from data as to the environmental conditions of each catchment (climate, soil erodibility, slope, percentage of plant cover, age of the reafforestation pines, etc.) and of the channels (texture, roughness, etc.). The real time of check dam fill is contrasted with the estimated sedimentation period (ESP), establishing the fit between both variables. Finally, the mean lifespan of the dam receptacle and the mean number of events causing filling is indicated, bearing in mind the rhythm of liberation and sediment transfer (solid discharge transferred to the channel -TQs-, final sediment transference coefficient - FST- ) and the age of the structures. Chapter 7 - In river basins, groundwater dynamics often condition the spatio-temporal patterns of runoff generation and discharge. Hence, water table level controls the patterns of “Dunne” runoff generation or saturation excess overland flow. In this study geomorphic changes of a complex gully system in Swaziland’s Middleveld were traced from 1947 to 1998. For this purpose, High-resolution Digital Terrain Models (HDTMs) were generated, based on aerial photographs. The gully system shows a complex history, that involves fluvial erosion and mass movement processes. During the observation period, 104,500 m3 of material were eroded from an 11 ha gully contributing area. The evolution of gully growth is strictly depending on the deepening of gully bottom at the mouth (local erosion base level), that in turns is influenced by the temporary base level (regional erosion base level). Consequently, the longitudinal profile of the stream generates lateral subsurface head distributions. To investigate the escarpment retreat by groundwater erosion we developed a landscape evolution model with an integrated hydrologic module. Groundwater flow is simulated by a dynamic two-dimensional equation for an unconfined aquifer. This model was subsequently applied to evaluate the effect of groundwater fluctuations on the development of gullies and hence, on landscape evolution. In this paper we show that gully genesis and growth are closely related to the hydrological properties of a complex aquifer system. Chapter 8 - The tectonic history of the Siberian continental plate is discussed here at the main stages of geological chronicle: from Rodinia supercontinent, through Pangea supercontinent, up to present-day position of Siberia within the structure of Eurasia. We start from the end of Mesoproterozoic where the Rodinia supercontinent was assembled. The

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David M. Ferrari and Antonio R. Guiseppi

available geological and paleomagnetic data set suggests that at the Meso-Neoproterozoic boundary Siberian craton was a part of Rodinia supercontinent lengthening the Laurentia northward. The reconstruction implies that the southern (in modern coordinates) margin of Siberia was oriented towards the northern margin of Laurentia. Most likely Siberia represented a giant promontory in the southeast of Rodinia, because during the Late Mesoproterozoic and Early Mesozoic, the western, northern and eastern (in modern coordinates) margins of Siberia represented marginal marine basins opened to the ocean. New paleomagnetic data show that the Siberia - Laurentia disintegration during the Neoproterozoic Rodinia break-up has developed progressively from west to east along the southern (in modern coordinates) margin of the Siberian craton under the controlling role of strike-slips. During Neoproterozoic on the background of the Rodinia break-up in the west of the Siberian craton, a gradual transformation of passive continental margin into active continental margin occurred with a development of Late Neoproterozoic island arc systems. All of those processes have determined the further tectonic stile of Siberian craton during the Late Precambrian. The stage of accretion of the Neoproterozoic island arc to the Siberian paleocontinent has been going in pre-Vendian, however, even at the end of Vendian the regime of active continental margin was again resumed at least in the southwestern Siberian plate. Vendian to Earliest Paleozoic is the next important step in tectonic history of the Siberian plate. Its connecting to dynamics of development of the island arc system lies along the south to southwestern margin of the Siberian continent. Relicts of these island arcs formed the framework of the Caledonian structure of the Central Asia fold belt and appeared on the Altai-Sayan region (southwestern frame of Siberian craton). Geological and paleomagnetic data prove that the modern mosaic structure of this frame is the result of deformation of a primary stretching island arc system during its oblique accretion to the craton under the large-scale strike-slip conditions. Late Paleozoic dynamics of crust deformation of the Siberian plate at the stage of collision with Kazakhstan Baltica and Kara continents was most likely controlled by deep faults inherited from Early Paleozoic structure. At the end of the Paleozoic, strike-slips movements of tectonic domains within the structure of Eurasian continental plate have taken place. This key moment in the tectonic history of Siberia has been manifested by the dramatic trap eruption well known as the Siberian Large Igneous Province. Paleomagnetic evidence obtained for the Mesozoic of Siberia suggest Mesozoic geological history of Eurasia to be essentially determined by the strike-slip motions of large-scale tectonic domains within its structure. The synthesis of paleomagnetic data on the Mesozoic of Eurasia justifies a sinistrial strike-slip motion of the assemblage of Siberian structures relative to the European and North-China ones during the Mesozoic. This process is reflected by the clockwise rotation of the Siberian domain. The discrepancy in paleomagnetic pole positions of deferent domains demonstrate the systematic character and allow to be revealed the scales of strike-slip motions associated with this rotation and to propose a new tectonic model describing the history of the closure of Mongolo-Okhotsk paleoocean. Chapter 9 - Bouguer anomaly map of India has provided several medium and short wavelength anomalies that are discussed vis-à-vis regional and local tectonics. Fold Belts signifying Archean-Proterozoic collision zones similar to present day collision zones like Himalayas are characterized by linear gravity highs due to thrusted high density rocks flanked by gravity lows due to low density Proterozoic metasediments on one side and granitic

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

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Preface

xi

intrusions and crustal thickening on the other side representing foreland basins and subduction related magmatism, respectively. These characteristics have helped to divide the Indian Shield under various cratons and fold (mobile) belts and probable directions of their convergence during their collision. There have been large scale rifting and convergence in Northern and Eastern India during Paleo and Meso-Neo Proterozoic periods, respectively while the western and southern India is dominated by similar activities during Neo ArcheanPaleo Proterozoic period. Most of the Proterozoic collision of Indian cratons were direct giving rise to large scale thrusts except between Western and Eastern Dharwar cratons that was oblique and soft producing only a shear zone. Direction of convergence between various cratons of Indian Shield during Archean-Proterozoic period is all most opposite to the present day convergence across Himalayan Fold and Thrust Belts that is in conformity with the direction of movement based on paleomagnetic studies. Archean-Proterozoic fold belts being along the margins of large cratons probably help them to maintain their relative elevation in spite of millions of years of erosion and isostatic uplift. Large wavelength gravity anomalies are related to the present day lithospheric structures that suggest the average depth of lithosphere under Indian continent as 160-180 km that reduces to 140 km under lithospheric upwarp along the Himalayan front. The lithospheric mantle is primarily occupied by low density rocks of 3250 kg/m3 compared to surrounding rocks of 3300 kg/m3. These rocks may represent subducted Tethyan/Indian lithosphere and is supported from high velocity in seismic tomography. These low density rocks appear to be responsible for uplift of S. Indian Shield and present day fast movement of the Indian plate due to their buoyancy. It is further aided by the absence of high velocity keel of the Indian cratons as suggested from receiver function analysis. Gravity highs of lithospheric mantle in NW and SE India may represent the thinning of lithosphere or mafic intrusives during the break up of the Indian plate from Gondwana land caused by plumes. The part of lithospheric and crustal gravity highs in northern India under Ganga basin south of Himalayas can be attributed to lithospheric and crustal upwarp and associated intrusives due to flexure of the Indian plate. Spectral analysis of CHAMP satellite magnetic data also suggest a magnetic discontinuity at a depth of 150-160 km that represent the presence of cold subducted Indian/Tethyan lithosphere at this level where temperature is lower compared to the Curie point geotherm. Chapter 10 - Probably the most outstanding examples of the validity of the concept of terrane mobility and final accretion to a cratonal margin are provided by those terranes, now attached to the western North American cratonal margin, bearing Permian fusulinid (foraminiferal) and colonial rugose coral faunas. These terranes, which extend from Mexico to Alaska, are remnants of several different Permian paleobiogeographic provinces originally formed in different parts of the Paleopacific Ocean, as indicated by their distinctive faunas. Along the western margin of the North American craton, the Permian fusulinid and colonial rugose coral faunas vary considerably, but there are some marked similarities. Beyond this margin, there are three sets of terranes bearing different faunas that were accreted to the craton after Permian time. The first series, located mostly immediately west of the craton and commonly referred to as the McCloud Belt, bears somewhat different faunas from those of cratonal North America. Although the distance between these terranes and North America during the Permian is still debated, the faunal differences are substantial enough to suggest at least a moderate amount of original separation. Farther west there are terranes and blocks in mélanges that bear typical Tethyan faunas, which probably originated many

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David M. Ferrari and Antonio R. Guiseppi

thousands of kilometers farther out in the Paleopacific Ocean. Beyond these terranes is still another dispersed terrane, referred to as the Wrangellia terrane, with faunas somewhat related to those of the McCloud Belt. Data from the fusulinid and colonial coral faunas, with consideration of the available paleomagnetic data, suggest that many of these terranes had complicated histories, including changes in positions relative to the North American craton during the Permian. In the Early Permian the major terranes of the McCloud Belt were mostly at somewhat different latitudes relative to cratonal North America than they are today and perhaps 2000-3000 km offshore. The Wrangellia terrane lay farther north, but it also was separated from the North American craton by a considerable distance. The eastern Tethyan faunas occupied shelves around islands in the tropics far removed from North America. During the Middle Permian the terranes of the McCloud Belt and the Wrangellia terrane migrated about 15º southward relative to cratonal North America, and all of the terranes, including the eastern Tethyan terranes, may have begun to converge on the North American craton. In post-Permian time all of these terranes were accreted to the craton and smeared out thousands of kilometers along strike-slip faults at its margin. Chapter 11 - The North African atlasic belt, including the High Atlas, the Saharan Atlas, the Aurès-Tunisian segment and their Preatlasic zones, is located at the boundary of the North Africa and Sahara domains. This elongated chain, starting from the Morocco Atlas, near the Atlantic Ocean and extending farther eastward as far as the Tunisian Atlas fringing the Mediterranean Sea has experienced a polyhistoric evolution. Rifting and opening of the basins occurred during the Triassic and Jurassic times and are succeeded by a recovery of the synsedimentary tectonics during the Cretaceous, generating tilting of blocks and new subsidence episodes. Palaeogene and Neogene times registered alternating folding and sedimentary filling. The paleogeography of the Atlasic Basins changed significantly during their history. After the development of subsiding troughs filled with terrigenous and evaporitic sediments during the Triassic period, the Lias platforms spread over the entire Maghrebian domain and were followed, during the Middle Jurassic times, by terrigenous marine and deltaic deposits. Shallow marine carbonate and terrigenous platforms developed gradually during the Late Jurassic. The early Cretaceous was a period of widespread continental to coastal marine siliciclastic sedimentation supplied from the southernmost old African shields. The Late Cretaceous registered mainly carbonate deposits lasting to the Middle Palaeogene. The main folding phase occurred during the Middle Eocene. Postcollisional sedimentary basins formed during the Neogene in eastern Algeria and Tunisia, when western Algeria and Morocco were definitively emerged. The geodynamic evolution of the Atlasic chain, located between the Atlantic Ocean and the Eastern Mediterranean Basin on its margins and northwards bordered by the Maghrebian (Alpine) Ocean, is influenced by every one of these oceans. Like this, during the Triassic and Jurassic times the rifting of the Atlasic Basins is related to the Atlantic and MaghrebianLiguride Ocean opening, when, during the Cretaceous period, the rejuvenated extensional tectonics is correlated to that of the Neotethys south-margin. Short Communication A - Combining the holographic methods with the methods for digital image processing has made it possible to develop the digital holographic interference microscope (DHIM) for real-time 3D imaging of phase microscopic objects and measurement of their morphological parameters. The instrument integrates holographic interference

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

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Preface

xiii

microscope with digital processing of interferograms. For the first time it has become possible to obtain optically 3D images of native cells. In this chapter we present result of DHIM application for experimental study of the 3D morphology of biological and technical phase microscopic objects. They are human blood erythrocytes and thin films. It is demonstrated that, in addition to hematological diseases, the diseases of various genesis and external factors serve as the reason for the morphological modification of blood erythrocytes. It is detected that morphologic modifications are nonspecific. It is proved that erythrocyte 3D morphology reflects the state of a living organism and the level of its biological response on different external factors influence. The proposed 3D model of erythrocyte makes it possible to quantitatively estimate the effect of morphological modifications of blood erythrocytes on their functionality with respect to oxygen transfer. It is demonstrated that the observed morphological modifications of erythrocytes lead to a significant decrease in the blood oxygen capacity and can serve as a reason for hypoxia. It is demonstrated that DHIM can also be successfully used for transparent thin films 3D visualization and quantitative investigation. Short Communication B – Based on the Middle Triassic evolution of the carbonate platforms of the Alpine-Carpathian-Dinaric region two different types can be distinguished. The first is characterized by Middle-Upper Triassic terrestrial sediments together with volcanites. They suffered repeated uplift in the Anisian-Carnian: 1. Piz da Peres Conglomerate, (Bithynian); 2. Voltago Conglomerate, (Early Pelsonian); 3. Richthofen Conglomerate (Illyrian: Trinodosus zone/Trinodosus subzone); 4. Ugovizza Breccia 2 (upper Illyrian: Avisianum subzone); 5. Conglomerate and sandstone of Fassanian age; 6. Bauxite: Upper Ladinian-Carnian. The uplift was accompanied by volcanic activity, and followed by rapid subsidence. Carbonate platforms belonging to the first type can be found in the Dolomites, Carnic Alps, Julian Alps, South Karavank Mts., Bükk Mts., and External Dinarides. The age of the uplift is younger and younger as we proceed from the Dolomites towards the Carnic and Julian Alps, Karavanks, External Dinarids. On the southern shelf the platforms are small, and the shape is more or less round and the basins cover a much bigger area than platforms. The second carbonate platform type is characterized by the lack of terrestrial sediments and volcanics. Such platforms can be found in the Northern Calcareous Alps (NCA), the Western Carpathians (WNC) and the Drina Ivanjica Element of the Internal Dinarids. The ages of the drownings: 1. Balatonicus zone: Balatonicus subzone, 2. boundary between the Balatonicus and Trinodosus zones: Binodosus-Trinodosus subzones, 3. Reitzi zone: Avisianum subzone. The age of many terrestrial sediments, i.e., uplifts, coincide with that of the drowning events. On the northern shelf the platforms are big and have long, elongated shapes; the platforms cover a much bigger area than the basins. The carbonate platforms of the first type were deposited in the Triassic on the southern shelf, and the second type on the northern shelf of the ocean, the remnants of which build up the Dinaride Ophiolite Belt. The asymmetric evolution of the two shelves, and the younger and younger age of the uplift, and accompanying volcanic activity can be explained by mantle plume activity. Short Communication C - The problem is the definition of morphostructure diagnostic signs of the pay zones from the all territory of the sedimentary basin, for it study by precise and reliable methods so far as the search and the prospecting of the hydrocarbons in the

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deepwater regions at present technically are limited and economically no profitable. For solving this problem is using the bathymetric map of the continental margin of North-West Australia ( Carnarvon basin as a model ). For revealing of geomorphologic particularities of the pay zones in the considering basin with help of specialized GIS technology were processing digital maps (figure maps) of the bottom relief. Is determined that fields are situated in the narrow zone with frequent and disorderly changing of azimuth dip of the bottom surface of the continental margin, that is characteristic signs of the pay zone. Analogous trends are mapping in the more deepwater regions of the continental slope, so it may consider as prospective for hydrocarbons search.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

In: Geomorphology and Plate Tectonics Editors: D. M. Ferrari, A. R. Guiseppi

ISBN: 978-1-60741-003-4 © 2009 Nova Science Publishers, Inc.

Chapter 1

COSMOGENIC NUCLIDES AND GEOMORPHOLOGY: THEORY, LIMITATIONS, AND APPLICATIONS Yingkui Li1 and Jon Harbor2 1

Department of Geography, University of Tennessee, Knoxville, TN, U.S.A. 2 Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, IN, U.S.A.

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ABSTRACT Since the mid 1980s, the use of in-situ-produced cosmogenic nuclide techniques has allowed rapid progress and unique advances in a wide range of areas in geomorphology and Earth-surface processes. Cosmogenic nuclides are produced by the interaction of cosmic rays with minerals at or near the Earth’s surface, and measurements of single or multiple nuclides in rocks or sediments can be used both as chronometers for surface exposure or burial time, and to unravel temporal and spatial variations in the rates and styles of geomorphic processes. As dating tools, cosmogenic nuclide approaches can be used over a wide range of timescales (103 – 106 years) and with a wide range of materials, providing unique opportunities to resolve issues that were previously unsolvable because of a lack of suitable materials and/or limited timescales for other dating methods. As a way to quantify geomorphic process rates and landscape evolution, cosmogenic nuclide techniques have been used to determine erosion, weathering, accumulation, and soil formation rates at landform and landscape scales. This has allowed reassessment of many traditional opinions, hypothesis, and models in geomorphology and Earth-surface processes, and development of updated ideas based on new abilities to examine processes and landscape evolution. In this paper, we review the use of cosmogenic nuclides in geomorphology and Earth-surface processes, summarize uncertainties and limitations related to current understanding of the physical properties of cosmogenic nuclides, as well as sampling and measurement, and examine applications of cosmogenic nuclide techniques to various areas of geomorphology and Earth-surface processes, including glacial chronology and geomorphology, geomorphic process rates, tectonic geomorphology, and landscape evolution.

Keywords: Cosmogenic nuclide; Surface exposure age; Burial dating; Erosion rate; Landscape evolution

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

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ABBREVIATIONS P: P0 : PA0: PB0: P: Pteff :

production rate (atoms g-1 yr-1) surface production rate (atoms g-1 yr-1) surface production rate of nuclide A (atoms g-1 yr-1) surface production rate of nuclide B (atoms g-1 yr-1) watershed average production rate (atoms g-1 yr-1) effective production rate in transport (atoms g-1 yr-1)

N: N(t): N: NA: NA(0) : NB: NB(0) : Np : NT: Ninit: t: t* : T, Tburial: tt : s: ε: m: m: x: ρ: Λ: µ: λ: λ* : λA: λB:

nuclide concentration (atoms g-1) nuclide concentration after exposure t (atoms g-1) average nuclide concentration (atoms g-1) concentration of nuclide A (atoms g-1) nuclide A concentration before burial (atoms g-1) nuclide B concentration (atoms g-1) nuclide B concentration before burial (atoms g-1) pre-burial nuclide concentration (atoms g-1) nuclide concentration with burial time, T (atoms g-1) nuclide concentration at start transport (atoms g-1) exposure time (yr) effective half life ( t* = ln2/λ*) (yr) burial time (yr) effective transport time or exposure duration (yr) deposition rate (cm/yr) site-specific erosion rate (cm/yr) site-specific erosion rate (g cm-2 yr-1) watershed average erosion rate (g cm-2 yr-1) depth below the surface (cm) density of the overburden (g cm-3) absorption mean free path (g cm-2) nucleon absorption coefficient (µ =ρ/Λ)(cm-1) cosmogenic nuclide decay constant (yr-1) effective decay constant (λ* =λ + με) (yr-1) decay constant of nuclide A (yr-1) decay constant of nuclide B (yr-1)

1. INTRODUCTION Great improvements in the precision of Accelerator Mass Spectrometry (AMS) (e.g. Elmore and Phillips, 1987; Muzikar et al., 2003) and highly sensitive conventional noble-gas mass spectrometry since the mid 1980’s have lead to revolutionary developments in the study of geomorphology, quaternary geology and geochronology through the application of in-situ-

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1

produced cosmogenic nuclide techniques (Gosse and Phillips, 2001). Cosmogenic nuclides are produced when cosmic rays interact with minerals at or near the Earth’s surface. Because the concentrations of various cosmogenic nuclides in a sample are a function of its history of exposure at or near the surface, measurements of single or multiple nuclides in rocks or sediments have been used as chronometers for surface exposure. In addition, measurements of multiple nuclides have been used to unravel burial time and temporal and spatial variations in rates and styles of geomorphic processes. As dating tools, cosmogenic nuclide approaches can be used to determine both surface exposure ages (e.g. Dorn and Phillips, 1991; Nishiizumi et al., 1993; Cerling and Craig, 1994) and burial dates (e.g. Granger and Muzikar, 2001) over a wide range of timescales and materials. This provides unique opportunities to resolve issues that were previously unsolvable because of a lack of suitable materials for radiocarbon and other traditional dating methods (Bierman, 1994; Fabel and Harbor, 1999; Gosse and Phillips, 2001). As a way to measure geomorphic process rates and landscape evolution, cosmogenic nuclide techniques have been used to determine erosion rates from small areas to large watershed scales, sediment accumulation rates, and weathering and regolith/soil formation rates (e.g. Brown et al., 1995, 1998; Bierman and Steig, 1996; Granger et al., 1996; Small et al., 1997, 1999). This has allowed reassessment of traditional opinions, hypothesis, and models in geomorphology, as well as the development of updated ideas based on new abilities to examine processes and landform development (e.g. Granger et al., 1996; Small et al., 1997, 1999; Heimsath et al., 1999, 2001; Riebe et al., 2000; Vance et al., 2003). Nonetheless, cosmogenic nuclide techniques are not a panacea, and there are still significant issues that cannot be resolved or fully constrained because of limitations and uncertainties inherent in current cosmogenic nuclide techniques (Dorn and Phillips, 1991; Bierman, 1994; Gosse and Phillips, 2001). However, both the analytical techniques and the interpretive models used in cosmogenic nuclide applications continue to be refined and improved. Review and evaluation of past methods and applications are very important to stimulate new ideas for cosmogenic nuclide technique applications and methods development. Because of the rapid rise in publications in which cosmogenic nuclide techniques have been used, there have been several reviews examining the characteristics of cosmogenic nuclides, AMS measurement processes and their applications to geomorphic and geochronological questions (e.g. Lal, 1991; Dorn and Phillips, 1991; Cerling and Craig, 1994; Bierman, 1994; Gosse and Phillips, 2001; Watchman and Twidale, 2002; Muzikar et al., 2003; Bierman and Nichols, 2004). This paper provides an updated overview and summary of cosmogenic nuclide techniques for the general Earth Sciences audience, focusing on applications in geomorphology. This review includes the general characteristics of in-situ-produced cosmogenic nuclides and their interpretation methods; uncertainties or limitations in cosmogenic nuclide techniques, geomorphic conditions, sampling and measurement instruments; and applications in various areas of geomorphology and landscape evolution. Additional information on the approach is available in comprehensive reviews intended for researchers using this method, for example Gosse and Phillips (2001).

1

Common acronyms include CN (Cosmogenic Nuclides), TCN (Terrestrial Cosmogenic Nuclides), CRN (Cosmogenic Radio Nuclides), and SED (Surface Exposure age Dating).

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

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2. IN-SITU-PRODUCED COSMOGENIC NUCLIDES: A GENERAL DESCRIPTION The Earth is continually bombarded by ionizing radiation from extraterrestrial sources, commonly referred to as cosmic rays (Gosse and Phillips, 2001). These cosmic rays include high-energy nucleons, which have sufficient energy to produce nuclear disintegrations in the upper atmosphere, producing a cascade of particles and reactions with the nuclei of atoms in the atmosphere (Gosse and Phillips, 2001). Particles with sufficient energy can penetrate into the upper few meters of the Earth’s surface where they interact with minerals in rocks and sediments to generate cosmogenic nuclides, including the stable nuclides 3He, 21Ne and the radioactive nuclides 10Be, 14C, 26Al and 36Cl (Cerling and Craig, 1994; Bierman, 1994; Handwerger et al., 1999; Gosse and Phillips, 2001) (Table 1). Table 1. General properties of commonly used cosmogenic nuclides Nuclide

Half-life (yr) Stable

Primary target minerals Olivine, Pyroxene, Amphibole, Garnet

Measurement techniques MS*

Major reaction mechanisms

10

1.36 × 106

AMS (BeO)

Spallation on Si, Mg, O, Fe

14

5730

Quartz, Olivine, Magnetite, Plagioclase Quartz

AMS (C)

Spallation on Si and O

21

Stable

MS*

Spallation of Mg, Al, Si, Fe

26

7.05 × 105

Quartz, Olivine, Garnet Quartz, Olivine

AMS (Al2O3)

Spallation on Si, Al, Fe

36

3.01 × 105

Whole rock

AMS (AgCl)

Spallation on K and Ca; neutron capture on Cl

3

He Be C Ne Al

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Cl

Spallation of O, Mg, Si, Fe

* MS: Mass Spectrometry

Cosmogenic nuclides are produced primarily by three types of interactions between cosmic particles and minerals: spallation, neutron-capture reactions (thermal neutron 2 activation) and muon-induced reactions (both fast muons and capture of negative muons) (Lal, 1991; Cerling and Craig, 1994; Bierman, 1994; Heisinger and Nolte, 2000; Heisinger et al., 2002a, 2002b). Different interactions dominate at different depths below the Earth’s surface. In the top meter, production is generally by neutron-induced spallation and neutroncapture reactions. Below this, production is mainly by muon-induced reactions (Lal, 1991; Cerling and Craig, 1994).

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Spallation is a nuclear reaction collision between nuclei and highly energetic protons and neutrons, in which the target nuclei are broken into smaller nuclei and other emitted particles. Neutron-capture reactions refer to the capture of slow (thermal) neutrons, whose energy level is in the range of thermal vibrations, by target nuclei in rocks and sediments. A muon is a short-lived energetic particle that interacts weakly with atoms and can penetrate deeply into rocks and sediments. These terms are explained in more detail in Gosse and Phillips (2001).

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Spallation-induced production decreases exponentially with depth (Figure 1) and can be modeled by a simple exponential law (e.g. Lal, 1991; Brown et al., 1992):

P = P0 e − μx

(1)

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where P is the production rate, x is depth below the surface, µ is a nucleon absorption coefficient given by µ =ρ/Λ, where ρ is the density of the overburden and Λ is the absorption mean free path, and P0 is the production rate at the surface, which depends on latitude and altitude (Lal, 1991). All symbols are defined in the ABBREVIATIONS section. In contrast, thermal neutron nuclide production generally increases between the surface and a depth of about 15-20 cm and then decreases exponentially with the depth (Dep et al., 1994a, 1994b; Liu et al., 1994; Bierman et al., 1995; Gillespie and Bierman, 1995). Muon-induced production includes both slow and fast muon components. They are all functions of depth, but are not readily modeled by simple analytic expressions (Brown et al., 1995; Stone et al., 1998b; Granger and Smith, 2000; Heisinger and Nolte, 2000; Braucher et al., 2003; and discussed in detail in Heisinger et al., 2002a, 2002b).

Figure 1. Depth profiles of production rates induced by spallation, capture of negative mouns (stopped muons), reactions with fast mouns, and total production rates for 10Be, 14C, 26Al, and 36Cl (modified from Heisinger and Nolte, 2000, with permission from Elsevier). m.v.e is water equivalent depth in meters.

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With prolonged exposure, cosmogenic nuclides accumulate in rock surfaces as a function of time and surface erosion rates (Lal, 1991; Fabel and Harbor, 1999). Assuming that the production rate is steady through time at a specific location, and that it is primarily induced by nucleon spallation, the rate of change in the cosmogenic nuclide concentration for a rock surface can be described as (e.g. Lal, 1991; Braucher et al., 2000):

dN = P (x ) − (λ + uε ) N (t ) dt

(2)

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where N(t) is the cosmogenic nuclide concentration at an exposure time, t, P(x) is the production rate variation with depth, x, and λ is the cosmogenic nuclide decay constant. ε is the erosion rate, and λ + με is often referred to as the effective decay constant, λ*, (λ* =λ + με) with a corresponding effective half life (t*, t* = ln2/λ*) (Lal, 1991; Gillespie and Bierman, 1995). Generally, the growth curve for a spallogenic nuclide can be divided into three sections (Gillespie and Bierman, 1995; Figure 2): (1) a quasi-linear growth section where exposure time is shorter than one effective half-life with negligible surface erosion (N ≈ Pt); (2) a slow growth section where exposure time is within several orders of effective half-lives, with obvious impact of erosion (Equation 2); and (3) a steady-state section where equilibrium is approached between production and loss by decay and erosion after 3 or more effective half-lives (N = P / (λ + με)).

Figure 2. Normalized growth curve of spallogenic cosmogenic nuclides (modified from Gillespie and Bierman, 1995 by permission of American Geophysical Union)

The production rates of cosmogenic nuclides vary with latitude, altitude, solar activity, and time (Lal, 1991; Gosse and Phillips, 2001; Muzikar, et al., 2003). The impact of latitude is more significant for production rates at low latitudes than at high latitudes. For example, production due to spallation at sea level at the equator is ~60% of its value at sea level at 60º latitude (Muzikar, et al., 2003) and does not change much above 60º latitude (Lal, 1991; Gosse and Phillips, 2001). The production rate is lower at lower altitudes because cosmic rays have to pass through a greater thickness of the atmosphere before reaching the Earth’s

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surface. For instance, at 40º latitude, the production rate induced by spallation is about two times greater at 800 m than at sea level (Muzikar, et al., 2003). Temporal variations in production rates come mainly from magnetic field variations through time (Dunai, 2001a; Desilets and Zreda, 2003). In addition, solar activity also affects the temporal variation of production rates due to impacts on the intensity of the magnetic field (Lal, 1988; Masarik and Beer, 1999) and the impact of solar activity on nuclide production rates is more sensitive in high latitude areas (Lifton et al., 2005).

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3. SAMPLE PREPARATION AND MEASUREMENT The sampling strategy for research using cosmogenic nuclide analysis depends primarily on the purpose of the research. In most studies, samples are taken from rock or sediment surfaces in geologic settings of interest to determine the duration of surface exposure and to constrain the surface erosion rate. For some research questions a series of samples are taken from different depths in a profile extending from the surface to several meters below the surface. Profiles are often used to evaluate the rate of sediment accumulation and the average nuclide inheritance. When a sample is taken, the field scientist also collects detailed information about the sample site including latitude, longitude, altitude, rock type, depth of the sample, and surface slope. The field scientist also records elevation angles and bearings from the surface to any features that might shield the sample site from incoming cosmic radiation. In order to produce sufficient target element (e.g. Be and Al) to be measured, a sufficient sample size must be taken in the field. Determining the appropriate sample size (which is often several hundred grams of rock or sediment) requires knowledge of the research goal, the intended target elements, the mineralogical makeup of the sample, and sample site characteristics. Guidance for determining the approximate weight of samples to be taken can be found at https://www.physics.purdue.edu/ams/rosetest/samplewt.php, and a detailed discussion of sampling strategies is provided in Gosse and Phillips (2001). Once a sample has been collected, subsequent physical and chemical preparations typically take on the order of several weeks or months. The first step is to extract and separate the target mineral (e.g. quartz) from the sample using physical and chemical processes, and then the target element (e.g. Be and Al) is extracted from the target mineral and purified. Although these processes are relatively standardized and improved techniques for separating target minerals and elements are continuously being developed, this is a highly technical and labor intensive process. Once the target element has been extracted, measurement of target nuclide (e.g. 10Be) is typically achieved using AMS or highly sensitive conventional noble-gas mass spectrometry because of the extremely small inventories of cosmogenic nuclides in a sample. The basis of the technique is the measurement of nuclide ratios in a sample by ionization, acceleration through an electric field, and separation by mass and charge in a magnetic field. Figure 3 provides a layout the AMS system at Purdue University.

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Figure 3. A layout of the AMS system at the Purdue Rare Isotope Measurement Laboratory (PRIME Lab), Purdue University (provided by PRIME Lab).

4. TRADITIONAL INTERPRETIVE MODELS Both single nuclide and nuclide-pairs have been used in a wide range of Earth-science problems to evaluate surface exposure ages, erosion rates, and burial events. To understand the use of cosmogenic nuclides in geomorphology, it is important to understand common interpretive models and analysis strategies and their corresponding assumptions and limitations.

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4.1. Single Nuclides Common interpretive models that use single nuclides are based on the assumption of constant production rate for nuclides through time (Table 2). In addition, such models only consider spallation produced cosmogenic nuclides, whereas if other sources of production are important, for example with 36Cl, more complex interpretive methods are needed (see, for example, Zreda et al., 1991 and Gosse and Phillips, 2001). Some interpretive models listed in Table 2 have conflicting assumptions, so caution should be used in applying multiple models to a single situation. For example, two assumptions commonly used in surface exposure studies are (1) zero-erosion since exposure and (2) that a sample is in erosional equilibrium. The zero-erosion assumption leads to a minimum exposure age estimation for spallation-dominated nuclides. The erosional equilibrium assumption leads to a maximum estimate of the surface erosion rate. These two estimates are very important in geomorphic research. However, the minimum age and maximum erosion rate cannot be used simultaneously because they have conflicting assumptions. Rather, these two assumptions should be used to produce a set of internally consistent erosion rate and exposure age pairs. Other geomorphic evidence can be used to narrow down the range of acceptable erosion rates and thus exposure ages, or vice versa.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers, Incorporated, 2009.

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Table 2. Interpretive models for single nuclides Purpose

Material* Equation B, C, S

P0 N= e −ux λ + uε

B, C, S

N = Pt

B, C, S

N=

B, C, S

N=

B, C

t=−

B, C

t=

B, C, S

t=−

B, C, S

t=−

Short exposure time (< one effective half-life)

Concentration

Exposure age

P0 e −ux (1 − e −( λ +uε )t ) λ + uε P

λ − μs

(e − μx − e − λx / s )

λN ⎞ ⎛ ln⎜1 − ⎟ P ⎠ λ ⎝ 1

N P

1

λ + uε

Assumptions Steady-state erosion; no burial

⎛ ( λ + uε ) N ⎞ ln ⎜1 − ⎟ P ⎝ ⎠

1 ⎛ (λ − us ) N ⎞ ln ⎜1 − ⎟ P λ − us ⎝ ⎠

Description If the erosion rate is zero, then the concentration of the nuclide at the surface is a maximum value For short exposure time, concentration is not sensitive to erosion rates

Most general description of nuclide concentration increase with exposure time; Can be simplified to the upper two cases with different assumptions Uniform rate of deposition Applies to a surface on which material with depth of material on the surface x has been deposited uniformly over time Zero-erosion of the The exposure age can be underestimated if there surface; only for is erosion; commonly given as an apparent age radioactive nuclides, no but actually is the minimum exposure age burial Zero-erosion of the Same description as above but can also be used surface; for stable for radioactive nuclides to estimate short time nuclides; no burial exposure The erosion rate must be known or reasonably Steady erosion; no burial assumed; For stable nuclides or high erosion rates (λ 1Ma) surfaces (Gosse and Phillips, 2001), and combining 14C with a stable or longer-lived nuclide (such as 10Be) would produce a ratio suitable for young surfaces (2.65Ma) (Nishiizumi et al., 1991a; Brook et al., 1995; Ivy-Ochs et al., 1995) to the late Holocene ( 103-104 kyr) erosion rates of bedrock surfaces, and is based on an assumption that local erosion keeps pace with the production of transportable material by weathering processes (Small et al., 1997). Erosion or accumulation rates at the sediment (regolith or soil) surface, and thus regolith/soil production rate can also be measured through nuclide concentration-depth analysis (Braucher et al., 1998, 2000; Small et al., 1999; Heimsath et al., 1999, 2001; Phillips, 2000). Site-specific bedrock erosion rates can be directly calculated under the assumption of steady-state surface erosion, giving a maximum erosion rate estimate from spallationproduced nuclides. By studying the bare bedrock surface erosion rates on summit flats in four western US mountain ranges using in-situ-produced cosmogenic 10Be and 26Al, Small et al. (1997) found that the bare bedrock is not weathered into transportable material more rapidly in alpine environments than in other environments. Measurements in other areas show similar results especially in the absence of liquid water (e.g. Nishiizumi et al., 1991a, 1993; Leland et

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al., 1998; Summerfield et al., 1999; Bierman and Caffee, 2001; Clapp et al., 2002). Studies also show that bare rock surfaces probably weather less rapidly than rock mantled with regolith/soil because the water required for frost weathering is limited on bare rock surfaces (Small et al., 1999). In the alpine environment examined by Small et al. (1999), the production rate beneath ~90cm of regolith is nearly twice as fast as the average regolith production rate on bare rock surfaces. In an arid region drainage basin, Yuma Wash, southwestern Arizona, examined by Clapp et al. (2002), the long-term rates of upland sediment generation are 81±5 g m-2 yr-1, which is much faster than the rates measured from bedrock surfaces (30±2 g m-2 yr-1). In addition, the measurement of bedrock weathering and regolith production can be used to test general theories of landform evolution. For example, Small et al.’s bedrock surface erosion studies (1999) were used to test Gilbert’s steady state hillslope hypothesis and Heimsath et al.(1999, 2001) developed a quantitative model to estimate the rate of soil formation using cosmogenic nuclides and used soil depth variations with hillslope curvature to test whether hillslopes approached dynamic equilibrium. For sediment (regolith or soil), concentration-depth profile analysis of cosmogenic nuclides provides another powerful way to determine the site-specific erosion or accumulation rates (e.g. Braucher et al., 1998, 2000; Small et al., 1999; Phillips, 2000; Gosse and Phillips, 2001). For example, Braucher et al. (1998, 2000) provided detailed studies of erosion rates and the formation of the stoneline of Brazilian laterite using concentration depth relationships of in-situ-produced 10Be. Phillips (2000) introduced a numerical model to estimate cumulative soil accumulation rates and hillslope erosion through cosmogenic nuclide concentration-depth profiles.

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6.4. Watershed Scale Erosion Understanding denudation, erosion rates and sediment transportation characteristics at different spatial scales is critical for developing new insight into large-scale landscape evolution. In theory, the concentration of in-situ-produced cosmogenic nuclides in sediment discharged by a river can be used to determine the average long term erosion rate for the watershed as a whole if: (1) the near-surface distribution of the target mineral (typically quartz) is relatively uniform throughout the watershed; (2) erosion is sufficiently rapid that loss of cosmogenic nuclides is primarily through erosion rather than radioactive decay; (3) there is little long-term sediment storage (Brown et al., 1995, 1998; Bierman and Steig, 1996; Granger et al., 1996). Under these conditions, the long-term denudation rate of the watershed can be determined by measurement of the nuclide concentration divided by the average production rate of the watershed (Brown et al., 1995, 1998; Bierman and Steig, 1996; Granger et al., 1996). High nuclide concentrations imply that the material comes from a slowly eroding setting and, conversely, relatively low concentrations imply more rapid erosion rates in the source area (Brown et al., 1998). Measurement of denudation rates using cosmogenic nuclides has been applied to many watersheds in different climatic zones and under a range of geologic and geomorphic conditions from small (1-10 km2) (e.g. Brown et al., 1995; 1998; Granger et al., 1996; Riebe et al., 2000; Bierman and Caffee, 2001; Clapp et al., 2001; Matmon et al., 2003a) to relatively large (102-105 km2) (Schaller et al., 2001; Vance et al., 2003) spatial scales. Generally, small watersheds more closely match the assumptions required in the calculation of denudation

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rates using cosmogenic nuclides and may have larger variances in erosion rate than larger basin areas (e.g. Matmon et al., 2003a). For large watershed measurements, complex lithology, relief and erosion-deposition patterns in the watershed should be evaluated in interpreting the results (Schaller et al., 2001). Determining denudation rates is critical in efforts to quantify and understand rates and styles of landscape evolution. Granger et al. (1996) found an exponential relationship between long-term erosion rates and average hillslope gradients in data from two small watersheds in the Fort Sage Mountains of California. However, erosion rates cannot always be inferred from hillslope gradient alone, because landscapes can evolve toward a state of erosional equilibrium, in which steep and gentle slopes erode at similar rates (Riebe et al., 2000). Vance et al. (2003) made the first direct measurements of watershed erosion rates in the rapidly uplifting mountain belt from the Upper Ganges catchment in the Himalaya and found that a log-linear relationship between relief and erosion rate held over three orders of magnitude variation in erosion rate and between very different climatic and tectonic regimes. Matmon et al. (2003b) also found a strong dependence of erosion rate on slope in the Great Smoky Mountains, a relatively stable tectonic setting. There are limitations and problems in measuring watershed denudation rates using cosmogenic nuclides. Quartz enrichment by the selective dissolution of relatively soluble minerals may introduce a significant bias in the measurements (Small et al., 1999). Riebe et al. (2001) suggested that the erosion rate bias introduced by dissolution is generally less than 12% on the basis of 22 granitic catchments from various temperate climates. For some applications a major limitation in erosion rates measured by cosmogenic nuclides is that they are long-term average values, and thus do not provide a way to examine accelerated erosion that can result from human impacts or rapid climate change (Bierman and Steig, 1996). However, this also provides opportunities for the comparison of the long-term natural erosion with human-induced erosion (Brown et al., 1998), and for examining erosion rates over different time scales and geomorphic events (Clapp et al., 2000; Kirchner et al., 2001).

6.5. Depositional Landforms Cosmogenic nuclides can be used to date various depositional landforms, such as fluvial terraces (e.g. Hancock et al., 1999; Hetzel et al., 2002; Schildgen et al., 2002), alluvial fans (e.g. Nishiizumi et al., 1993; Liu et al., 1996), beach terraces (e.g. Nishiizumi et al., 1993; Trull et al., 1995), and depositional surfaces of piedmonts (Nichols et al., 2002). Direct measurements of exposure duration for such landforms have been used to link their formation to specific climatic or tectonic signals (see also section 5.2). For example, Trull et al. (1995) used surface exposure dating methods for beach terraces to reconstruct the chronology of paleo-lake levels, which was then related to climatic change signals. Schildgen et al. (2002) dated fluvial fill terraces in steep canyons that drain glaciated catchments in Colorado Front Range, and showed how the fill events relate to glacial history. However, exposure age determinations for depositional landforms can be very complicated because the sediment typically has inherited nuclide concentrations derived from prior exposure in source areas (Liu et al., 1996; Matmon et al., 2003c). For example, Liu et al. (1996) found 36Cl ages of alluvial surfaces on piedmont slopes in Southern Arizona were older than 14C and soil ages, as a result of inheritance. Matmon et al. (2003) found complex

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exposure burial and transport histories of the chert clasts from the beach ridges of late Pleistocene Lake Lisan, southern Israel. These studies suggest that although cosmogenic nuclide accumulation can help establish chronologies for depositional landforms, care must be used in evaluating the effects of complex exposure histories and inheritance. Recent advances in detailed measurement of cosmogenic nuclide concentrations across sediment profiles have been proved as a reasonable way to determine the mean inheritance, and thus, calculate sediment accumulation rate and sediment transportation (Hancock et al., 1999; Bierman and Nichols, 2004).

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6.6. Other Applications In addition to the major applications of in-situ-produced cosmogenic nuclides in Earth science discussed above, other areas which have great potential for new insights from cosmogenic nuclide studies include karst, aeolian, loess, planetary, and periglacial geomorphology. In karst geomorphology, cave sediments have been used to determine burial ages that provide insight in to the chronology of cave formation as well as insight into regional tectonic characteristics (Granger et al., 1997, 2001; Boaretto et al., 2000). For aeolian and loess processes, Nishiizumi et al. (1993) measured five samples from sand dunes and showed repeated cycles of near-surface exposure, followed by burial at depth. Nishiizumi et al. (1993) also used apparent exposure ages for glacially derived loess from New Zealand and Germany to discuss the relationship between loess and glaciations. For planetary geomorphology, Nishiizumi et al. (1991b) and Phillips et al. (1991) provided comparative analyses of exposure ages of the Meteor Crater, Arizona, using in-situ-produced 10Be-26Al and 36Cl. These examples illustrate the more general point that cosmogenic nuclide techniques can be used in a wide range of geomorphic studies, only some of which have been described here. As more geomorphologists become proficient in using the technique, and in gathering the resources needed to work with this method, many more applications are likely to be developed.

7. FUTURE RESEARCH Although there has been rapid development in cosmogenic nuclide techniques in recent decades, several major elements of future research will further enhance the method and its potential applications. First, methodological needs include: (1) improving production rate estimates for individual nuclides and production ratios for different nuclide pairs or triplets; (2) refining important nuclear parameters such as the absorption mean free path (Λ) and the nuclide decay constant (λ) that affect the nuclear interactions in rock as well as the muonic contributions for the nucleonic production; and (3) advancing understanding of spatial scaling, geometric shielding and temporal variation of nuclide production. These will reduce uncertainties and limitations and increase the possibility of solving new problems in areas such as risk assessment and environmental geology (Gosse and Phillips, 2001). Second, there is strong need for increased precision in AMS measurement and sample preparation, to reduce systematic errors and the size of samples need for an analysis. Third, continuous development

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of new methods using these techniques is important. For example, techniques for 41Ca, 10Be in magnetite and olivine, 21Ne in garnet, methods for using three or more nuclides in a single rock or sediment sample to constrain exposure or burial events; and calculations for different scenarios of geomorphic processes with complex geo-histories. Fourth, refined understanding of the relationship between cosmogenic nuclide data and the geomorphic processes being studied is needed. Improved understanding of geomorphic processes associated with cosmogenic nuclide production, accumulation and loses, such as multiple exposure-burial events and limited erosion processes which are insufficient to completely remove the cosmogenic signal, can greatly extend the application of the cosmogenic nuclide technique. Finally, despite the impression given by the length of the reference section of this paper, to date there have actually been relatively few applications of cosmogenic nuclide techniques to geomorphology compared to the scale of potential uses of the method. More case studies in different locations and in different areas of geomorphology will provide many more possibilities to advance our understanding of Earth surface processes and landscape evolution. Improving the precision to resolve short timescale issues will also lead to increased use of the method, and in particular to studies that combine process-based geomorphic models with cosmogenic nuclide work to resolve more systematic and complicated geoscientific issues.

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REFERENCES Ackert Jr, R.P.; Singer, B.S.; Guillou, H.; Kaplan, M.P.; Kurz, M.D. Earth Planet. Sci. Lett. 2003, 210, 119-136. Balco, G.; Stone, J.O.H.; Porter, S.C.; Caffee, M.W. Quat. Sci. Rev. 2002, 21, 2127-2135. Bard, E. Science 1997, 277, 532-533. Bard, E. Geochim. Cosmochim. Acta 1998, 62, 2025-2038. Bard, E.; Raisbeck, G.; Yiou, F.; Jouzel, J. Earth Planet. Sci. Lett. 1997, 150, 453-462. Bard, E.; Raisbeck, G.; Yiou, F.; Jouzel, J. Tellus 2000, 52B, 985-992. Barrows, T.T.; Stone, J.O.; Fifield, L.K.; Cresswell, R.G. Quat. Res. 2001, 55, 179-189. Barrows, T.T.; Stone, J.O.; Fifield, L.K.; Cresswell, R.G. Quat. Sci. Rev. 2002, 21, 159-173. Bierman, P.R. J. Geophys. Res. 1994, 99(B7), 13885-13896. Bierman, P.R.; Caffee, M. Am. J. Sci. 2001, 301, 326-358. Bierman, P.R.; Nichols, K.K. Annu. Rev. Earth Planet. Sci. 2004, 32, 215-255. Bierman, P.R.; Steig, E.J. Earth Surf. Proc. Landforms 1996, 21, 125-139. Bierman, P.R.; Gillespie, A.; Caffee, M.; Elmore, D. Geochim. Cosmochim. Acta 1995, 59(18), 3779-3798. Bierman, P.R.; Marsella, K.A.; Patterson, C.; Davis, P.T.; Caffee, M. Geomorphology 1999, 27, 25-39. Boaretto, E.; Berkovits, D.; Hass, M.; Hui, S.K.; Kaufman, A.; Paul, M.; Weiner, S. Nucl. Instrum. Methods Phys. Res. B 2000, 172, 767-771. Braucher, R.; Bourlès, D.L.; Colin F.; Brown, E.T.; Boulangé, B. Earth Planet. Sci. Lett. 1998, 163, 197-205. Braucher, R.; Bourlès, D.L.; Brown, E.T.; Colin, F.; Muller, J.P.; Braun, J.J.; Delaune, M.; Edou Minko, A.; Lescouet, C.; Raisbeck G. M.; Yiou, F. Chem. Geol. 2000, 170, 95–111.

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Braucher, R.; Brown, E.T.; Bourlès, D.L.; Colin F. Earth Planet. Sci. Lett. 2003, 211, 251258. Briner, J.P.; Swanson, T.W. Geology 1998, 26, 3-6. Briner, J.P.; Swanson, T.W. Quat. Res. 2001, 56, 148-154. Brook, E.J.; Kurz, M.D. Quat. Res. 1993, 39, 1-10. Brook, E.J.; Kurz, M.D.; Ackert, R.P.; Denton, G.H.; Brown, E.T.; Raisbeck, G.M.; Yiou, F. Quat. Res. 1993, 39, 11-23. Brook, E.J.; Kurz, M.D.; Ackert, R.P.; Raisbeck, G.; Yiou, F. Earth Planet. Sci. Lett. 1995, 131, 41-56. Brown, E.T.; Brook, E.J.; Raisbeck, G.M.; Yiou, F.; Kurz, M.D. Geophys. Res. Lett. 1992, 19, 369-372. Brown, E.T.; Stallard, R.F.; Larsen, M.C.; Raisbeck, G.M.; Yiou, F. Earth Planet. Sci. Lett. 1995, 129, 193-202. Brown, E.T.; Stallard, R.F.; Larsen, M.C.; Bourles, D.L.; Raisbeck, G.M.; Yiou, F. Earth Planet. Sci. Lett. 1998, 160, 723-728. Cerling, T.E. Quat. Res. 1990, 33, 148-156. Cerling, T.E.; Craig, H. Annu. Rev. Earth Planet. Sci. 1994, 22, 273-317. Cerling, T.E.; Webb, R.H.; Poreda, R.J.; Rigby, A.D.; Melis, T.S. Geomorphology 1999, 27, 93-111. Clapp, E.M.; Bierman, P.R.; Schick, A.P.; Lekach, J.; Enzel, Y.; Caffee, M. Geology 2000, 28, 995-998. Clapp, E.M.; Bierman, P.R.; Nichols, K.K. Quat. Res. 2001, 55, 235-245. Clapp, E.M.; Bierman, P.R.; Caffee, M. Geomorphology 2002, 45, 89-104. Clark, D.H.; Bierman, P.R.; Larsen, P. Quat. Res. 1995, 44, 367-377. Clark, D.H.; Bierman, P.R.; Gillespie, A.R. Radiocarbon 1996, 38(1), 152. Davis, P.T.; Bierman, P.R.; Marsella, K.A.; Caffee, M.W.; Southon, J.R. Ann. Glaciol 1999, 28, 181-188. Dep, L.; Elmore, D.; Fabry-Martin, J. Nucl. Instrum. Methods Phys. Res. B 1994a, 92, 321325. Dep, L.; Elmore, D.; Lipschutz, M.; Vogt, S.; Phillips, F.M.; Zreda, M.G. Nucl. Instrum. Methods Phys. Res. B 1994b, 92, 301-307. Desilets, D.; Zreda, M. Earth Planet. Sci. Lett. 2001, 193, 213-225. Desilets, D.; Zreda, M. Earth Planet. Sci. Lett. 2003, 206, 21-42. Desilets, D.; Zreda, M.; Lifton, N.A. Earth Planet. Sci. Lett. 2001, 188, 283-287. Dorn, R.I.; Phillips, F.M. Phys. Geog. 1991, 12(4), 303-333. Duk-Rodkin, A.; Barendregt, R.W.; Tarnocai, C.; Phillips, F.M. Can. J. Earth Sci. 1996, 33, 875-895. Dunai, T.J. Earth Planet. Sci. Lett. 2000a, 176, 157-169. Dunai, T.J. Earth Planet. Sci. Lett. 2000b, 178, 425. Dunai, T.J. Earth Planet. Sci. Lett. 2001a, 193, 197-212. Dunai, T.J. Earth Planet. Sci. Lett. 2001b, 188, 289-298. Dunai, T.J.; Wijbrans, J.R. Earth Planet. Sci. Lett. 2000, 176, 147-156. Dunne, J.; Elmore, D. Earth Planet. Sci. Lett. 2003, 206, 43-49. Dunne, J.; Elmore, D.; Muzikar, P. Geomorphology 1999, 27, 3-11. Elmore, D.; Phillips, F.M. Science 1987, 236, 543-550. Fabel, D.; Harbor, J. Ann. Glaciol. 1999, 28, 103-110.

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Yingkui Li and Jon Harbor

Fabel, D.; Stroeven, A.P.; Harbor, J.; Kleman, J.; Elmore, D.; Fink, D. Earth Planet. Sci. Lett. 2002, 201, 397-406. Fabel, D.; Harbor, J.; Dahms, D.; James, A.; Elmore, D.; Horn, L.; Daley, K.; Steele, C. Ann. Assoc. Am. Geogr. 2004, 94(2), 241-255. Fabel, D.; Fink, D.; Fredin, O.; Harbor, J.; Land, M.; Stroeven, A.P. Quat. Res. 2006, 65, 136-146. Gillespie, A.R.; Bierman, P.R. J. Geophys. Res. 1995, 100(B12), 24637-24649. Gosse, J.C.; Phillips, F.M. Quat. Sci. Rev. 2001, 20, 1475-1560. Gosse, J.C.; Evenson, E.B.; Klein, J.; Lawn, B.; Middleton, R. Geology 1995a, 23(10), 877880. Gosse, J.C.; Klein, J.; Evenson, B.; Middleton, R. Science 1995b, 268, 1329-1333. Granger, D.E.; Smith, A.L. Nucl. Instrum. Methods Phys. Res. B 2000, 172, 822-826. Granger, D.E.; Muzikar, P.F. Earth Planet. Sci. Lett. 2001, 188, 269-281. Granger, D.E.; Kirchner, J.W.; Finkel, R. J. Geol. 1996, 104, 249-257. Granger, D.E.; Kirchner, J.W.; Finkel, R.C. Geology 1997, 25(2), 107-110. Granger, D. E.; Fabel, D.; Palmer, A. N. Geol. Soc. Am. Bull. 2001, 113, 825-836. Hallet, B.; Putkonen, J. Science 1994, 265, 937-940. Hancock, G.S.; Anderson, R.S.; Chadwick, O.A.; Finkel, R.C. Geomorphology 1999, 27, 4160. Handwerger, D.A.; Cerling, T.E.; Bruhn, R.L. Geomorphology 1999, 27, 13-24. Harbor, J.; Stroeven, A.P.; Fabel, D.; Clarhäll, A.; Kleman, J.; Li, Y.K.; Elmore, D.; Fink, D. Geomorphology 2006, 75, 90-99. Heimsath, A.M.; Dietrich, W.E.; Nishiizumi, K.; Finkel, R.C. Geomorphology 1999, 27, 151172. Heimsath, A.M.; Dietrich, W.E.; Nishiizumi, K.; Finkel, R. Earth Surf. Proc. Landforms 2001, 26, 531-552. Heisinger, B.; Nolte, E. Nucl. Instrum. Methods Phys. Res. B 2000, 172, 790-795. Heisinger, B.; Lal, D.; Jull, A.J.T.; Kubik, P.; Ivy-Ochs, S.; Neumaier, S.; Knie, K.; Lazarev V.; Nolte, E. Earth Planet. Sci. Lett. 2002a, 200, 345-355. Heisinger, B.; Lal, D.; Jull, A.J.T.; Kubik, P.; Ivy-Ochs, S.; Knie, K.; Nolte, E. Earth Planet. Sci. Lett. 2002b, 200, 357-369. Hetzel, R.; Niedermann, S.; Ivy-Ochs, S.; Kubik, P.W.; Tao, M.; Gao, B. Earth Planet. Sci. Lett. 2002, 201, 575-591. Horn, L.; Harbor, J.; Elmore, D. Radiocarbon 1996, 38(1), 49-50. Hotchkis, M.; Fink, D.; Tuniz, C.; Vogt, S. Appl. Radiat. Isot. 2000, 53, 31-37. Ivy-Ochs, S.; Schlüchter, C.; Kubik, P.W.; Dittrich-Hannen, B.; Beer, J. Geology 1995, 23, 1007-1010. Jackson, J.; Ritz, J.F.; Siame, L.; Raisbeck, G.; Yiou, F.; Norris, R.; Youngson, J.; Bennett, E. Earth Planet. Sci. Lett. 2002, 195, 185-193. Kirchner, J.W.; Finkel, R.C.; Riebe, C.S.; Granger, D.E.; Clayton, J.L.; King, J.G.; Megahan, W.F. Geology 200, 29, 591-594. Klein, J.; Giegengack, R.; Middleton, R.; Sharma, P.; Underwood, J.R.; Weeks, R.A. Radiocarbon 1986, 28, 547-555. Kohl, C.P.; Nishiizumi, K. Geochim. Cosmochim. Acta 1992, 56, 3583-3587. Kurz, M.D. Nature 1986a, 320, 435-439. Kurz, M.D. Geochim. Cosmochim. Acta 1986b, 50, 2855-2862.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

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Cosmogenic Nuclides and Geomorphology: Theory, Limitations, and Applications

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Kurz, M.D.; Colodner, D.; Trull, T.W.; Moore, R.B.; O’Brien, K. Earth Planet. Sci. Lett. 1990, 97, 177-189. Lal, D. Annu. Rev. Earth Planet. Sci. 1988, 16, 355-388. Lal, D. Earth Planet. Sci. Lett. 1991, 104, 424-439. Lal, D. Nucl. Instrum. Methods Phys. Res. B 2000, 172, 772-781. Lal, D.; Jull, A.J.T.; Burr, G.S.; Donahue, D.J. Nucl. Instrum. Methods Phys. Res. B 2000, 172, 623-631. Leland, J.; Reid, M.R.; Burbank, D.W.; Finkel, R.; Caffee, M. Earth Planet. Sci. Lett. 1998, 154, 93-107. Li, Y.K.; Harbor, J.; Stroeven, A.P.; Fabel, D.; Kleman, J.; Fink, D.; Caffee, M.; Elmore, D. Earth Surf. Proc. Landforms 2005, 30, 1039-1049. Li, Y.K.; Fabel, D.; Stroeven, A.P., Harbor, J. Geomorphology, 2008, 99, 139-149. Licciardi, J.M.; Kurz, M.D.; Clark, P.U.; Brook, E.J. Earth Planet. Sci. Lett. 1999, 172, 261271. Licciardi, J.M.; Clark, P.U.; Brook, E.J.; Pierce, K.L.; Kurz, M.D.; Elmore, D.; Sharma, P. Geology 2001, 29(12), 1095-1098. Lifton, N.A.; Bieber, J.W.; Clem, J.M.; Duldig, M.L.; Evenson, P.; Humble, J.E.; Pyle, R. Earth Planet. Sci. Lett. 2005, 239, 140-161. Liu, B.; Phillips, F.M.; Fabryka-Martin, J.T.; Fowler, M.M.; Stone, W.D. Water Resour. Res. 1994, 30, 3115-3125. Liu, B.; Phillips, F.M.; Pohl, M.M.; Sharma, P. Quat. Res. 1996, 45, 30-37. Marsella, K.A.; Bierman, P.R.; Davis, P.T.; Caffee, M.W. Geol. Soc. Am. Bull. 2000, 112, 1296-1312. Masarik, J.; Beer, J. J. Geophys. Res. 1999, 104, 12009-12111. Masarik, J.; Kollar, D.; Vanya, S. Nucl. Instrum. Methods Phys. Res. B 2000, 172, 786-789. Masarik, J.; Frank, M.; Schäfer, J.M.; Wieler, R. Geochim. Cosmochim. Acta 2001, 65(17), 2995-3003. Matmon, A.; Bierman, P.R.; Larsen, J.; Southworth, S.; Pavich, M.; Caffee, M. Geology 2003a, 31, 155-158. Matmon, A.; Bierman, P.R.; Larsen, J.; Southworth, S.; Pavich, M.; Finkel, R.; Caffee, M. Am. J. Sci. 2003b, 303, 817-855. Matmon, A.; Crouvi, O.; Enzel, Y.; Bierman, P.R.; Larsen, J.; Porat, N.; Amit, R.; Caffee, M. Earth Surf. Proc. Landforms 2003c, 28, 493-506. Miller, G.H.; Wolfe, A.P.; Steig, E.J.; Sauer, P.E.; Kaplan, M.R.; Briner, J.P. Quat. Sci. Rev. 2002, 21, 33-48. Mitchell, S.G.; Matmon, A.; Bierman, P.R.; Enzel, Y.; Caffee, M.; Rizzo, D. J. Geophys. Res. 2001, 106, 4247-4264. Muzikar, P.; Elmore, D.; Granger, D.E. Geol. Soc. Am. Bull. 2003, 115(6), 643-654. Napieralski, J.; Hubbard, A.; Li, Y.K.; Harbor, J.; Stroeven, A.P.; Kleman, J; Alm, G.; Jansson, K.N. J. Glaciol. 2007, 53, 71-83. Nichols, K.K.; Bierman, P.R.; Hooke, R.L.; Clapp, E.M.; Caffee, M. Geomorphology 2002, 45, 105-125. Nishiizumi, K.; Winterer, E.L.; Kohl, C.P.; Lal, D.; Arnold, J.R.; Klein, J.; Middleton, R. J. Geophys. Res. 1989, 94(B12), 17907-17915. Nishiizumi, K.; Kohl, C.P.; Arnold, J.R.; Klein, J.; Fink, D.; Middleton, R. Earth Planet. Sci. Lett. 1991a, 104, 440-454.

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Yingkui Li and Jon Harbor

Nishiizumi, K.; Kohl, C.P.; Shoemarker, E.M.; Arnold, J.R.; Klein, J.; Fink, D.; Middleton, R. Geochim. Cosmochim. Acta 1991b, 55, 2699-2703. Nishiizumi, K.; Kohl, C.P.; Arnold, J.R.; Dorn, R.; Klein, J.; Fink, D.; Middleton, R.; Lal, D. Earth Surf. Proc. Landforms 1993, 18, 407-425. Owen, L.A.; Gualtieri, L.; Finkel, R.C.; Caffee, M.W.; Benn, D.I.; Sharma, M.C. J. Quat. Sci. 2001, 16, 555-563. Owen, L.A.; Finkel, R.C.; Caffee, M.W.; Gualtieri, L. Geol. Soc. Am. Bull. 2002, 114(5), 593-604. Owen, L.A.; Spencer, J.Q.; Ma, H.; Barnard, P.L.; Derbyshire, E.; Finkel, R.C.; Caffee, M.W.; Zeng Yong, N. Boreas 2003a, 32, 281-291. Owen, L.A.; Finkel, R.C.; Ma, H.; Spencer, J.Q.; Derbyshire, E.; Barnard, P.L.; Caffee, M.W. Geol. Soc. Am. Bull. 2003b, 11, 1356-1364. Phillips, F.M. Geomorphology 2003, 53, 199-208. Phillips, F.M.; Zreda, M.G.; Smith, S.S.; Elmore, D.; Kubik, P.W.; Sharma, P. Science 1990, 248, 1529-1532. Phillips, F.M.; Zreda, M.G.; Smith, S.S.; Elmore, D.; Kubik, P.W.; Dorn, R.I.; Roddy, D.J. Geochim. Cosmochim. Acta 1991, 55, 2695-2698. Phillips, F.M.; Zreda, M.G.; Benson, L.V.; Plummer; M.A.; Elmore, D.; Sharma, P. Science 1996, 274, 749-751. Phillips, F.M.; Zreda, M.G.; Gosse, J.C.; Klein, J.; Evenson, E.B.; Hall, R.D.; Chadwick, O.A.; Sharma, P. Geol. Soc. Am. Bull. 1997, 109(11), 1453-1463. Phillips, W.M. Nucl. Instrum. Methods Phys. Res. B 2000, 172, 817-821 Phillips, W.M.; McDonald, E.V.; Reneau, S.L.; Poths, J. Earth Planet. Sci. Lett. 1998, 160, 209-223. Phillips, W.M.; Sloan, V.F.; Shroder J.F. Jr.; Sharma, P.; Clarke, M.L.; Rendell, H.M. Geology 2000, 28, 431-434. Pigati, J.S.; Lifton, N.A. Earth Planet. Sci. Lett. 2004, 226, 193-205. Putkonen, J.; Swanson, T. Quat. Res. 2003, 59, 255-261. Riebe, C.S.; Kirchner, J.W.; Granger, D.E.; Finkel, R.C. Geology 2000, 28(9), 803-806. Riebe, C.S.; Kirchner, J.W.; Granger, D.E. Geomorphology 2001, 40, 15-19. Schäfer, J.M.; Tschudi, S.; Zhao, Z.; Wu, X.; Ivy-Ochs, S.; Wieler, R.; Baur, H.; Kubik, P.W.; Schlüchter, C. Earth Planet. Sci. Lett. 2001, 194, 287-297. Schaller, M.; Blankenburg, F.V.; Hovius, N.; Kubik, P.W. Earth Planet. Sci. Lett. 2001, 188, 441-458. Schaller, M.; Blankenburg, F.V.; Veit, H.; Kubik, P.W. Geomorphology 2002, 49, 255-267. Schildgen, T.; Dethier, P.; Bierman, P.; Caffee, M. Earth Surf. Proc. Landforms 2002, 27, 773-787. Shanahan, T.M.; Zreda, M. Earth Planet. Sci. Lett. 2000, 177, 23-42. Small, E.E.; Anderson, R.S.; Repka, J.L.; Finkel, R. Earth Planet. Sci. Lett. 1997, 150, 413425. Small, E.E.; Anderson, R.S.; Hancock, G.S. Geomorphology 1999, 27, 131-150. Steig, E.J.; Wolfe, A.P.; Miller, G.H. Geology 1998, 26, 835-838. Stone, J.O. J. Geophys. Res. 2000, 105(B10), 23753-23759. Stone, J.O.; Ballantyne, C.; Fifield, L.K. Geology 1998a, 26, 587-590. Stone, J.O.; Evans, J.M.; Fifield, L.K.; Allan, G.L.; Cresswell, R.G. Geochim. Cosmochim. Acta 1998b, 62(3), 433-454.

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Stroeven, A.P.; Fabel, D.; Harbor, J.; Hättestrand, C.; Kleman, J. Geog. Annaler. 2002a, 84A, 275-287. Stroeven, A.P.; Fabel, D.; Hättestrand, C.; Harbor, J. Geomorphology 2002b, 44, 145-154. Sugden, D.E.; Balco, G.; Cowdery, S.G.; Stone, J.O.; Sass, L.C. Geomorphology 2005, 67, 317-334. Summerfield, M.A.; Stuart, F.M.; Cockburn, H.A.P.; Sugden, D.E.; Denton, G.H.; Dunai, T.; Marchant, D.R. Geomorphology 1999, 27, 113-129. Trull, T.W.; Brown, E.T.; Marty, B.; Raisbeck, G.M.; Yiou, F. Chem. Geol. 1995, 119, 191207. Trull, T.W.; Kurz, M.D.; Jenkins, W.J. Earth Planet. Sci. Lett. 1991, 103, 241-256. Vance, D.; Bickle, M.; Ivy-Ochs, S.; Kubik, P.W. Earth Planet. Sci. Lett. 2003, 206, 273-288. Van der Woerd, J.; Ryerson, F.J.; Tapponnier, P.; Gaudemer, Y.; Finkel, R.; Meriaux, A.S.; Caffee, M.; Guaguang, Z.; Qunlu, H. Geology 1998, 26(8), 695-698. Vogt, S.; Elmore, D.; Sharma, P.; Dunna, A. Radiocarbon 1996, 38, 122. Watchman, A.L.; Twidale, C.R. Earth Sci. Rev. 2002, 58, 1-49. Zech, W.; Glaser, B.; Abramowski, U.; Dittmar, C.; Kubik, P. W. Quat. Sci. Rev. 2003, 22, 2253-2265. Zreda, M.; Noller, J.S. Science 1998, 282, 1097-1099. Zreda, M.G.; Phillips, F.M. Geomorphology 1995, 14, 149-156. Zreda, M.G.; Phillips, F.M.; Elmore, D.; Kubik, P.W.; Sharma, P.; Dorn, R.I. Earth Planet. Sci. Lett. 1991, 105, 94-109. Zreda, M.G.; Phillips, F.M.; Kubik, P.W.; Sharma, P.; Elmore, D. Geology 1993, 21, 57-60.

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Chapter 2

FLOOD RISK AND LANDFORM OF CAMBODIAN MEKONG DELTA Shigeko Haruyama* and Takeshi Ito The Univ. of Tokyo, Graduate School of Frontier Science Kashiwa City, Chiba Pref. Japan

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ABSTRACT Flood risk zoning based on geomorphology for disaster mitigation is supporting the important fundamental knowledge for the regional disaster prevention work and urbanrural planning, that could help to reduce flooding damage and a number of victims of disaster. In our purpose of this study, the first one is accounting for the relationships between geomorphologic structures and flood dynamics explained for their special state and their changes of flood characteristics under the control of human activities, the other one is rendering the accurate mapping method explicit using satellite remote sensing technology for the specific flat landform landscape of the Mekong River delta in Cambodian territory. To examine the recent flooding dynamics of the Cambodian Mekong delta, geomorphologic land classification map showing flood types of the fluvial plain was prepared for discussion with flooding states and their transition in terms of time. The flooding extension mapping in time and space, was conducted to be adopted by the NRCS (Normalized Radar Cross Section) values which were given by numerical value series provided by JERS-1 SAR satellite imagery in monsoon season. In the results of our study, flood dynamics superintend the geomorphologic structures, such as inundation periods, inundation depths and flood flow direction on the Cambodian Mekong River delta. The authors To judge from the final result, -3.2dB is the most appropriate value for flood mapping of JERS-1 SAR. The chief distinction of flooding distribution of the monotone delta was elucidated that the scattered back swamps behind natural levee which is trend deep inundation, make apparent for high flood vulnerability as for the deepest and longest inundation period. On the other hand, alluvial terrace formed in Holocene and natural levee are showing trivial flooding than back swamp disputed geomorphologic structure.

* Correspondendence to : Shigeko Haruyama, The Univ. of Tokyo, Graduate School of Frontier Science, 5-1-5 Kashiwanoha, Kashiwa city, Chiba Pref. Japan, [email protected]

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Shigeko Haruyama and Takeshi Ito

Keywords: Mekong delta, Remote sensing, Land form, Flood dynamics

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1. INTRODUCTION Satellite remote sensing technology is the most effective methods of analyzing for flood dynamics of the large river basin expanding their watershed area constructed in continents. Ochi et al. (1991) used NDVI (Normalized Difference Vegetation Index) computed from NOAA-AVHRR satellite data to prepare a risk assessment map showing flood vulnerability zoning of Ganges delta in Bangladesh territory. Setojima and Akamatsu (1990) prepared an inundation zoning map of the Kokaigawa River basin in the central part of Japan, for applying the fuzzy level-slice processing of Landsat TM (specific band 2 using) imagery, and they showed their good relationships between inundation features and landform unit. Smith (1997) demonstrated a new method of overflow inundation analysis, using multi-spectrum scanner images in near-infrared band 7, and he showed that the microwave SAR (synthetic aperture radar) imagery has been available to get clear JERS-1 SAR images with high atmospheric transmittance, because the data are not influenced by climatic conditions in monsoon season. Giacomelli et al. (1995), Townsend and Walsh (1998), and Brivio et al. (2002) had attempted to determine a suitable threshold value of NRCS (Normalized Radar Cross Section) data calculated for applying the value of BSCV (back scattering coefficients values) that are exceed signal of the basic physical property of SAR data, and they defined the appropriate boundaries between inundation space and flood free space in the satellite images. Furthermore, Giacomelli et al. (1995) and Brivio et al. (2002) had tried to improve their remote sensing techniques analyzing inundation area by using DEM (Digital Elevation Model) data. Nico et al. (2000) successfully analyzed flood inundation extension process in the southern part of France comparing with SPOT images and normalized ERS-1 SAR images, and they found their good interrelation with both satellite images for flood extension mapping. Haruyama and Shida (2006) had been trying to analyze the flooding expansion process in advance and afterward on the lowest Vietnamese Mekong delta by using JERS 1 SAR image series in monsoon season, and they computed the NRCS values of the several flooding images and got that the suitable value is -18.dB for flood inundation area special mapping. They were proved to define micro-landform units of the Vietnam Mekong delta and have been used successfully to discriminate the states of landform structures and vegetation landscape under flood condition of the monotone landscape delta. Haruyama and Shida (2008) also had calculated the maximum flood flow probabilities by using the all of the hydrologic data carried out by International Mekong River Committee at the main Mekong river at Pakse observation station in Cambodia , where is the one of the fiducial points of the main Mekong river in recent 40years, and the authors obtained the minimum historical flooding flow record was 37,827m3/s occurred in 1995 and the maximum flood flow was 57,600m3/s happened in 1978. The recent huge historical flood record was occurred in 2000 flood, and this flood flow volume was recorded 47,604 m3/s which is meaning the second larger flood event in recent 40years. Cambodian Mekong delta was suffered severe flooding damage in local residents under flood occurred in 2000, and the flood pushed many infants and aged persons away to flood victims (see Table 1, Fig.1). Flood inundation has influence upon agriculture, such as specific paddy field in Cambodia, in 2000.

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Table 1. Flood flow rate in last 40 years at Pakse observation point in Cambodia

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Flood year 1978 2000 1984 1961 1997 1995

Flow rate ( m3/s ) 57600 47604 45500 44700 41847 37827

Calculate Flood Return period (year) 188.8 12.1 6.3 4.9 1.9 0.4

Order 1 2 3

Figure 1. Return period of flooding of the main Mekong River at Pakse observation point in Cambodia

In this study, the authors have prearranged to describe the typical landform landscape of Cambodian Mekong delta (see Fig.2) and to make the detail geomorphologic land classification map showing flood affected area aiming for discussion with flood state and expansion in the regular flood in 1995, because of the Cambodian importance for agriculture farming related by flood water resource originated by the main Mekong river. In the above study, the authors selected the satellite data obtained at flood period in 1995 that is deliberated on regular flood year, and the 2000 flood was picked up the historical flood events for analyzing flood dynamics on Cambodian Mekong delta. The satellite remote sensing data, such as, JERS-1 SAR imageries, was processed for visualizing to demonstrate the detail flood dynamics in time and space on the study area (see Fig.2).

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Shigeko Haruyama and Takeshi Ito

Figure 2. The main area of the large Cambodian Mekong Delta under flooding extension series on selected JERS -1 SAR images obtained by 1995 ( In the satellite data, Red color is showing the flood in September, green color is December, and blue color is June.)

The fluvial landform landscape of Cambodian Mekong delta is indicating extraordinary monotone and homogeneity spectacular, however, each fluvial landform unit provides their

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flood water receiving capacity which has been build and defined by each flood prone nature under the geomorphologic evolution in Holocene (Haruyama et al., 1996). Haruyama et al. (1996) had tried to denote the geomorphologic evolution of the central plain on Thailand and suggested the new method for describe the geomorphologic land classification map processed by Landsat TM images, and also they proposed that the all of the fluvial landform units of flood plain provide the landform vessels for stocking inundation water in proportion to their magnitude of flood. The objectives of our study are as followings; the first one is to make the suitable precision of NRSC values derived from JERS-1 SAR satellite imagery using flood expansion mapping of the Cambodian Mekong monotone delta, and the second aim is to clarify inundation expansion process during flooding season of Cambodian Mekong delta, and to examine their correlation between each fluvial landform units and their flood dynamics. Therefore, the third one is basic study to clarify their landform elements and the landform structure and composition of landform unites of Cambodian Mekong delta. To obtain our final results of the above objects, the authors has conducted the geomorphologic survey with bore hole investigation for understanding landform evolution in Holocene, and surface soil examination for making recent flooding sediment. After that, the authors carried landform relief measurement with leveling instrument at the typical geomorphologic landscape, and then the authors verified with remote sensing data and ground truth points eradicating mis-classification of geomorphologic mapping and flood inundation extension in space. And, finally, the authors conducted the social survey for local interviews and questionnaire of flooding expansion process experienced by the several local residents living in the typical landform units. The authors used JERS-1 SAR data taken in 1995 to represent regular flood dynamics of the study area. JERS-1 SAR imagery is the most useful for analyzing flood conditions in heavy rainfall, because of climatic condition free sensor as ALOS/PALSAR(L-band) in their system. Accomplishing investigation, the authors used the other remote sensing data as OPS data to verify our findings from JERS-1 SAR data. On purpose of detail landform classification, the authors used aerial photos taken by Mekong river commission in 1992 for landform interpretation, and their scale is 1:20000 in each and the all of the Cambodian Mekong delta was safekeeping in Ministry of Public Works after taken photograph pictures . The elevation of Cambodia Mekong delta is usually less than 10 m above sea level, and the flood plain in this delta has been suffered by severe flood running over the main river course every monsoon seasons. The flooding water level of the main Mekong channel usually arises from May to September and flooding continues to expand over all of their fluvial plain from August to December. Although flood severely disrupts both city and village of Cambodia, flood water provides an important natural resource constancy for sustainable agriculture, specific rice cultivation.

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Shigeko Haruyama and Takeshi Ito

2. DATA AND METHODOROLOGY 2.1. Data The remote sensing data set used in this research and a flow chart of our study is shown in Table 2, 3 and Fig.3.

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Table 2. Remote Sensing Data(SAR) used in this study

The main characteristics of JERS-1 SAR imagery are as followings; 1) frequency 1.275 GHz (L band), 2) wave length 23.5 cm, 3) polarized electromagnetic radiations, 4) HH: angle of incidence 38.7°, 5) observation width 75 km, 6) spatial resolutions (processing level 2.1) 12.5 m, 7) observation cycle 44 days. The main characteristics of JERS-1 OPS (VNIR) imagery are as followings; 1) four bands (band 1: 0.52 ~ 0.60μm, band 2: 0.63 ~ 0.69μm, band 3: 0.76 ~ 0.86μm, band 4: 0.76 ~ 0.86μm), 2) spatial resolutions 18m2, 3) observation cycle 44 days. Table 3. Remote Sensing Data(OPS(VNIR)) used in this study

The authors have carried out our field studies at August and December in 2004 and 2005, for ground truth of remote sensing data and geomorphologic survey with both hand-boring and machinery boring, measurement of landform units, sounding flood depth of each landform, sediment observation etc. In the field survey, we interviewed several local residents to verify inundation and identified their flood characteristics, such as, historical flood event and regular flood state which is showing flood depth, flood period, flow direction and flood expansion. The important locations of 156 flood data selected for ground truth of remote sensing data were determined by GPS on JERS 1 SAR data, and they were loaded into GIS

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(geographical information system) system in TNT mips software. JERS-1 SAR data and the other statistical data showing 1995 flooding were provided by Cambodian Ministry of Water Resources and Meteorology and the Ministry of Agriculture, Forestry and Fisheries in Phnom Penh. All of the historical flood data analysis were undertaken in GIS system by using TNT mips (Micro image Co.) .

JERS-1/SAR Geometry correction Filtering・Resampling Mosaic

1/100,000 topographical maps of Cambodia

calculation of backscatter coefficient σ 0[dB]=20lo g10 II＋ CF

[after inundation before inundation] three test area is set the histogram is read

OPS(VNIR)

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Geometry correction 幾何補正・リサンプリング Resampling・ Mosaic

decision of new threshold value

RGB画像より training area extraction from RGB image トレーニングエリア抽出

classification of inundation area or non-inundation area on the boundary of the threshold value

classification of inundat最尤法により湛水域・ ion area or non-inundation 非湛水域に分類 area using maximum likelihood method

accuracy assessment of inundation area extraction of JERS-1/SAR

investigation result of local inundation area

Figure 3. The Study Flow Chart illustrated the methodology

2.2. Processing of Satellte Data for Flood Mapping Firstly, JERS-1 SAR data (logical format, CEOS-BSQ, processing level 2.1) was imported to GIS (TNT mips) system. A 5×5 cells in these data were applied to remove the speckle noise that is produced peculiar in JERS-1 SAR data using lee filtering method. Secondly, a geometric correction was applied to all of the data using 15 ground control points (GCPs) per a satellite run derived from 1:100,000 scaled topographic map printed by JICA (Japan International Cooperation Agency) in 2000, and then the all of above data set was geometrically transformed using affine-transformation method. In this data analysis, the geometric error margin was kept less than 12.5×12.5 m, which was equivalent to spatial resolution of JERS-1 SAR data. Then, the JERS-1 SAR data were converted to NRCS values using their pixel values determined by the Shimada and Isoguchi (2002) method as following (1) equation:

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Shigeko Haruyama and Takeshi Ito

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NRCS = 20 log 10 I + CF [dB ]

(1)

where I is the -digital number (DN) of each pixel from the SAR standard processing result (level 2.1: amplitude expression) and CF is a calibration factor (-85.34). To remove their image noise remaining after Lee Filtering application, a P-median filters were applied for screening in each 5×5cell of data for making noise free image. After that application of these above methods, the processed imagery data were re-sampled for making image using the Nearest Neighbor method, and individual satellite images were united to produce a mosaic images in natural color. Finally, the satellite data were again re-sampling for making images using the Cubic Convolution method to matching spatial resolution in each 18×18m of JERS-1 OPS (VNIR) data. Next, JERS-1 OPS data were imported into GPS data as an approximation for JERS-1 SAR data, and a geometric corrections were obtained using GCPs point’s data and 1:100,000 scaled topographic maps above mentioned. These remote sensing processing method which was proposed in previous research by Haruyama and Shida in 2006, was applied to analyze geomorphology and flood of Cambodian Mekong delta for making geomorphologic land classification map and visualizing flooding condition on their imageries, so as to recognize flood inundation landscape and examine the specific NRCS values which was obtained by microwaves reflected against water surface, vegetation difference, and man maid structures zones etc. The flood peak discharge of the main Mekong river of Cambodian territory, usually occurs in each September in the study area. The OPS(VNIR) data was used to be analyzed for inundation zoning, and was made use of comparison with validate to JERS-1 SAR data, which was the primary tool used to be determined for inundation distribution and was related to fluvial landform units. The reflected microwave band of SAR data on the water surface, is usually recorded as a mark displaying their decreasing of signal strength. The lower NRCS values are showing the study points, where are usual marshy area or the permanent surface water, such as lake and river surface. In their contrast, the microwave reflections are diffused when the earth surface is not covered by flood water, and the NRCS values become larger than that in inundation period. The numerical range of NRCS values indicate is greater in emergent land and in the specific area covered by ever green vegetation. Understanding seasonal changes of NRCS values during flood-free period is very clear and the threshold of NRCS values between wet and dry is remarkable defined in our study. To determine the threshold of NRCS values identification of inundation area, we selected the three test areas, such as, the Tonle Sap River basin, the upper Mekong River basin, and the lower Mekong River basin (see Fig.4) to assess under their different magnitudes of flooding. Highly NRCS value is usually indicative of emergent land, and the lower values is showing indicative of inundation area. The range of NRCS values of above three test areas arranged from June to September (see Fig. 5) suggests that -3.2dB is the most suitable threshold value of NRCS for flood boundary finding, after calculation of NRCS values defining the threshold between flood and flood free in differential images produced before-and-after flooding. The flooding and flooding-free boundary was described in natural color images (R: band 2, G: band 3, B: band 1 in our study) and green color represents the area covered by vegetation, purple color indicates the area covered by murky water containing inorganic matter, and black

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color indicates clear water in their images (see Fig. 2). Finally, the maximum likelihood method was adopted flood classification processing of all of the JERS-1 SAR data.

Figure 4. Location map of the selected three test areas for finding NRCS threshold of flooding

3. IMAGE ANALYSIS FOR FLOODING IN EACH SEASON Inundation analysis using JERS-1 SAR data was revised on ground truth data (Fig.6), and further was verified for compensate by comparison with OPS(VNIR) data. The following indexes were used for the accuracy assessment with OPS (VNIR) data. The error margin E (%) was calculated as follows: E = (difference between the inundation area from OPS (VNIR) and JERS-1 SAR) / (inundation area from OPS (VNIR)) × 100

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Number of pixels

2500

-17 -15 -15 -17 -22 -14 -16 -19 -13 -15 -18 -13 -15 -17 -12 -14 -17 -12 -13 -16 -11 -13 -15 -11 -12 -14 -10 -12 -14 -9. 7 -11 -13 -9. 2 -10 -12 -8. 6 -9. 8 -11 -8. 1 -9. 2 -11 -7. 6 -8. -9.68 -7 -8. 1 -9 -6. 5 -7. -8.53 -6 -6. -7.95 -5. 4 -6. -6.38 -4. 9 -5. 7 -6 -4. 4 -5. -5.13 -3. 9 -4. -4.55 -3. 3 -3. -3.98 -2. 8 -3. 3 -3 -2. 3 -2. -2.72 -1. 7 -2. -1.15 -1. -1.2 5 -0.7 -0. -0.7 9 0.02 -0. 1 -0. 3 0.77 0. 4 0. 25 1.52 0. 0.93 84 2.28 1. 1.46 43 3.03 1. 2.99 03 3.79 2. 2.52 62 4.54 3. 3.06 21 5.29 3. 3.59 81 6.05 4. 12 4. 4 6.8 4. 4.65 99 7.56 5. 5.18 58 8.31 5. 6.73 18 9.06 6. 6.35 77 9.82 7. 7.35 41 10.6 8.16 11.7 10 13.6

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4000 4000 4000

3500 3500 3500

3000 3000 3000

1500 1500 1500

1000 1000 1000

500 500 500

0 000

a:TonleSap river

b:upper of Mekong river c:lower of Mekong river

2500 2500

2000 2000

S( dB N R C S（ ｄ NBNR)RC CS（ ｄ B ))

Figure 5. The NRCS range showing three test areas from June to September in 1995

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We prepared the error-matrix of reference for accuracy evaluation method presented by Sohn et al. (2005). The index of coincidence (κ ) for two matrices representing a interpreted value and a true value is defined as follows; r

N κ＝

r

∑ x − ∑ (x ii

i =1

N2 −

i+

× x +i )

i =1

r

∑ (x

i+

× x +i )

i =1

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where r is the number of matrix rows -xii is the number of observations on path I, rows i, xi+ is the sum total of path i, -x+i is the sum total of row i, and N is the total number of pixels.

Figure 6. Location map showing the ground control points to validate for satellite data

Fig.7 shows the inundation interpreted images by JER-1 SAR data applying to two NRCS thresholds between -1.8 dB and -3.2 dB in 1995 flooding data. We selected 86 GCPs points for confirmation ground truth points, affirming different types of each landform unit and different water conditions. Making use of ground truth data, the satellite remote sensing imageries were interpreted and were corresponded each pixels on the satellite data. The

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Shigeko Haruyama and Takeshi Ito

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eternal water surfaces spotted on wet lands and lakes were misinterpreted at the very most in 1.8 dB, but they were appropriately interest rate interpreted in -3.2 dB of NRCS value. The misinterpretation of eternal water surfaces remarkably decreased under -3.2 dB NRCS on the river surface (see Fig.8) of August and September in 1995 flooding, when the water level of river has been rapidly rising. 105

105

12

12

threshold value -3.2(dB) inundation area of September

threshold value -1.8(dB) inundation area of September 11

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12

12

11

11

11

105

105

105

105

12

12

12

12

threshold value -3.2(dB) inundation area of December

threshold value -1.8(dB) inundation area of December 11

11

105

：inundation area

11

11

105

：non-inundation area

Figure 7. Inundation interpreted in September(upper image) and December(lower image) adopted to 1.8dB and -3.2dB

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Figure 8. Flood mapping of JER-1 SAR images using different two NRCS values (-1.8 dB in upper and -3.2 dB in lower)

Table 4 shows the result of validation between -1.8 dB and -3.2 dB for accuracy assessment of comparison between pixel data and ground control for correspondence and inconsistency under JERS-1 SAR data, and the two threshold value of NRCS threshold are affirmed and demonstrate. In the case of the NRCS threshold -3.2 dB using flood inundation area, the accuracy rate of the analysis is quite well 90.6% rather than -1.8 dB. In order to compare with JERS-1 SAR data processed inundation mapping and OPS (VNIR) data for validation, the error margin is small 11.1% in the case of -3.2 dB, and 33.4% in the case of 1.8 dB. Thus, the accuracy rate f inundation analysis using -3.2 dB was superior than the 1.8

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Shigeko Haruyama and Takeshi Ito

dB. Because of good accuracy rate of -3.2 dB, the authors employed the threshold for analyzing of flood dynamics in the study area Table 4. Accuracy assessment under the threshold between 1.8 dB and -3.2 dB for correspondence and inconsistency

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Table 5. Inundation area and error margin rate of three test areas using two threshold of JERS-1 SAR data and OPS data

The inundation areas and error margin rates of three test area are shown in Table 5, and the error margin rates calculated in the Tonle sap river basin and Upper part of Mekong river basin is only 6.8% in -3.2 dB but the error rate in the lower part of Mekong river basin is 18.9% in the same condition. The error rates of the total three test areas are 11.1% and this rates is quite good for analyzing flood inundation of JERS-1 SAR data. OPS data for validation for JERS-1 SAR data is showing the producer’s accuracy 94.6% in non-inundation and 66.7% in inundation (Table 6) using -1.8 dB. In the contrast, producer’s accuracy 77.7% in inundation and 85.4% in non-inundation (Table 7) using -3.2 dB. Overall accuracy comparison between SAR and OPS data was showing 89.2% in the case of -3.2dB and was showing 83.9％ in the case of -1.8dB for flooding analyzing. The κ coefficient was 0.64 in the case of -3.2dB and was 0.55 in the case of -1.8dB. The κ coefficient of 0.64 in the case of

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-3.2 dB shows that the accuracy of the interpreted is superior with - 3.2dB, which verifies the outcome of error margin calculations. Table 6. Accuracy assessment between SAR analysis and OPS data of validation for inundation interpretation using -1.8 dB

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Table 7. Accuracy assessment between SAR analysis and OPS data of validation for inundation interpretation using -3.2 dB

4.THE EFFECT OF LANDFORM UNITS FOR FLOODING Carbonnel (1972) recognized the five Quaternary marine terraces on the great plain of Cambodia and suggested this landform showing the sea level change science Pleistocene. Van et al. (2000), Ta et al. (2001, 2002), and Tanabe et al. (2003) had analyzed the Holocene sediments from all bore boring samples obtained in Don Tap Province and they described the former coastline of 4000y BP explaining geological evolution of the lowest Vietnamese Mekong delta. Maxwell (2002) described several natural environmental changes in Cambodian Mekong Delta including rapid climatic warming at 8,500 y BP, and he discussed the sea level rises in Holocene. Tanabe et al. (2003) also had documented the emergence of Mekong delta of the boundary with Cambodia and Vietnam territories, as their result of a drop of sea level before 7,000 y BP. Collecting the geological evolution results originated

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from above previous studies, landform of Cambodian Mekong delta has been developing for large sedimentation science early Holocene, and the boundary zone between Vietnam and Cambodia territories has been affected by sea level change in early Holocene. Flood plains of Cambodian Mekong delta are surrounded by river terraces and marine terraces. These river terraces are divided into three zones shown in (a) northeast of Phnom Penh, between the Tonle Sap River and the Mekong River; surface of these river terraces is flat, and their altitude is around 10m and their surface soils consist of thin yellowish white hard silt clay with scattered red mottle containing many granule, which indicate progressing laterization. (b) The Southeast of Phnom Penh on the right hand side of the main Mekong River; the elevation of these river terraces are lower than the other river terraces and their altitude is around 7 to 10 m. The top soil of terrace consists of brownish hard fine to medium sand and the lower sediment of the river terrace is grayish white clay to sand with yellowish mottle, which indicates alternation of dry and wet periods in Pleistocene. The river terrace near residual hill show the different sediment facies, which consist of white brownish silt in upper part and white layer with brown mottle in lower layer. (c) The southwest of Phnom Pen on the right hand side of the Bassac River; there are alluvial terraces belonging to the elevation 10m or below 10m, whose top soil consists of brownish silt to clay in upper part and lower layer becomes grayish white silt to clay matrix with gravel. The geomorphologic landscape of the river terraces indicating their sedimentation between Pleistocene and Holocene are different dimension meaning natural environmental change. Holocene geomorphologic evolution of the Cambodian Mekong delta is remarkable for developing natural levee building up and preparing the meandering system on the main Mekong river basin in Cambodia. The main Mekong River basin consists of two segments, such as, 1) Phonm Penh zone whose riverbed gradient is gentle 0.10/10,000, and there are many marshy areas spreading out in contrast to their southern part where is disappear of natural levees, 2) Kompong Cham zone whose riverbed gradient is steeper 1.33/10,000, and there are successive natural levees and large point bars with meandering system. The special distribution patterns of the large point bars system mean that the main channel of the Mekong River changed frequently its river course and very rapidly in torrential rainfall in monsoon season. The Bassac River is also repeated their river channel meandering, and their specific development of natural levee built up their unique landforms with colmatages landform formed under human activities. Because the landform landscape related with colmatage is very artificially by using irrigating water inducing from main channel into paddy field located in the back marshes, and the flooding sediment transported by colmateges is usually brought from the Bassac River. The Tonle Sap River repeats their diversion channels and confluent channels in several points. The distribution patterns of their channels in the Tonle Sap river basin are restricted by the river terraces where is developed in both sides. These river valley has a distinctive flood plain landform landscapes, compared with the other zones, which caused by an annual cycle of fair current and adverse current between the Mekong River and Tonle Sap lake in a year. The authors described the geomorphologic land classification map showing flood affected plain (see Fig.10) and we defined their each geomorphologic characteristic of Cambodian Mekong delta. The typical combinations of geomorphologic landform elements of our study areas are as following; 1) the Mekong River basin; alluvial fan + large natural levee with back swamp, 2) the Tonle Sap River basin; lacustrine delta + natural levee with

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back swamp, 3) the Bassac River basin; small natural levees with back swamp. The flood plain landform element of Cambodian Mekong delta is dominated by natural levees branching and meandering river course, and is the specific relief structures affected by annual water level changes of Tonle Sap Lake whose water level is higher in rainy season and lower in dry season. The Tonle Sap River flows downstream from Tonle Sap lake in dry season, but it usually reverses its direction from the main Mekong river in rainy season. The flood plain geomorphologic elements of our study area are demonstrating the geomorphologic land classification map as follows; 1) alluvial fans and dissected alluvial fans formed branching rivers are subsistence in surrounding the fringes of hills and in the western margin of flood plain, 2) alluvial terraces distributed around the residual hills and their elevations is around 6–10m above mean sea level. Two types of Holocene alluvial terraces are recognized for high terraces (over 8m) and low terraces (below 8m), 3) natural levee where highly natural levee is formed along the main river courses, and is affected by severe flood in monsoon climax however drains very well. These area extends across the border line and lower part in Vietnam territory, 4) the former river courses are traced by crescent-shaped lakes along the main river course and are filled with water in a year, 5) back swamps filled with flooding water, are usually tendency toward deeply inundated during rainy season. There are two landform types showing inundation depths, such as type 1 where is inclination of deep inundation and type 2 where is trend to shallow inundation depth with shorter flood period. These geomorphologic landform units are producing their capacity of flood inundation, and they have flooding buffer zones controlling floodwaters in advance because of stagnation. To ascertain the effect of repeated flooding on the destruction and reformation of landform elements, it is important to understand the flood flow direction and the flood inundation depth at the peak of their flood in each landform element. By considering together the time series of flooding expansion which was analyzed by JERS-1 SAR images and the capacity of flood for each landform unit, it is clear that JERS-1 SAR images can be used to monitor floodwater propagation for commencement of flood water filling in several back swamp at June, and to stagnate floodwater in each back swamp behind natural levees in August, and after that, the flood is noticeable to overflow from the main Mekong river and spreading widely most back swamps and lower natural levee zones in September indicating the maximum water level in a year. The Roads along the river courses and artificially piled structures for evacuation place on the alluvial plain of Cambodian Mekong delta remain the safety places from flooding in September. The relationships between flooding characteristics and landform units are as follows; 1) The landform affected by the longest period of inundation (more than six months) is back swamp(deeper stagnation type) 2) The landform of back swamp experiences shallow inundation for less than four months. However, these areas where urban expansion of the suburban of Phnom Penh has led to residential zone and also agricultural crop land development over previous back swamps, and they are the most vulnerable place in flood period 3) Natural levees is a suffered by high flood water but the flood water overflow them during flooding. The flood waters recede rapidly in this zone. 4) Former river courses are the most vulnerable areas through the flood season and are affected by rapid run of flood flow.

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Shigeko Haruyama and Takeshi Ito

Figure 10. Geomorphologic land classification map showing the flood affected area in Cambodian delta

CONCLUSION In this study, the authors classified the geomorphologic landforms in Cambodian Mekong delta and demonstrated geomorphologic land classification map showing the flood affected area. The typical combinations of geomorphologic elements of our study areas are as following; 1) the Mekong River basin; alluvial fan + large natural levee with back swamp, 2) the Tonle Sap River basin; lacustrine delta + natural levee with back swamp, 3) the Bassac River basin; small natural levees with back swamp. The flood plain geomorphologic elements are compared with flooding characteristics, such as, 1) alluvial fans and dissected alluvial fans are corresponding to flash flood, 2) natural levee is corresponding to severe flood but stagnation in short period. 3) Former river courses and back swamp is deeply inundated during flooding and there are two types inundation depth and these geomorphologic units affect flood inundation and have some buffer zones controlling floodwaters in advance.

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To ascertain the effect of repeated flooding on the destruction and reformation of landform elements, it is important to understand the flow direction and the inundation depth at the peak of flood in each landform element. Compared JERS-1 SAR images with flood characteristics. In this study, we clarified the relationship between flooding and landforms such as inundation expansion process, inundation depth, flood flow during flooding in Cambodian Mekong delta. After calculation of NRSC values derived from JERS-1 SAR satellite imagery, we got the result that NRCS threshold value of -3.2 dB is appropriate for flood analysis using JERS-1 SAR imagery.

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REFERENCES Brivio, P.A., Colombo, R., Maggi, M., Tomasoni, R. (2002) Integration of remote sensing data and GIS for accurate mapping of flooded areas. International Journal of Remote Sensing. 23(3):429-441. Carbonnel, J.P. (1972) Le Quaternaire Cambodgien Structure et Stratigraphie, Memoir 60, Orstom. Paris (In French) Giacomelli, A., Mancini, M.., Rosso, R. (1995) Assessment of Flooded Area from ERS-1 PRI Data: An application to the 1994 flood in northern Italy. Phys. Chem- Earth. 20(5-6): 469-474. Haruyama,S., Okura, H., Simking, T., Simking, R. (1996): Geomorphologic zoning for flood inundation using satellite data. Geo-Journal .38: 273–278. Haruyama, S., Shida, K. (2006): Flood risk evaluation of the Mekong River Delta utilizing JERS 1 SAR Images, Journal of Geography. 115(1): 72-86 (In Japanese with English abstract) Haruyama, S. Shida,K. (2008): Geomorphologic land classification map of the Mekong Delta utilizing JERS-1S SAR Images, Hydrological Process.22:1373-1381. Kubo,S.(2002): Geomorphologic features around Phnom Penh, lower Mekong Plain and an Extreme flood in 2000, Proceedings of the general meeting of the association of Japanese geographers. 61: 252. (In Japanese) Maxwell, A.L.(2002) :Holocene Monsoon changes inferred from lake sediment pollen and carbonate records. Northeastern Cambodia. Quaternary Research. 56(3): 390-401. Nico, G.., Pappalepore, M., Pasquariello, G., Refice, A., Samarell, S. (2000): Comparison of SAR amplitude vs. coherence flood detection methods―a GIS application. International Journal of Remote Sensing. 21(8): 1619-1631. Oya,M. (1993): River Geography. Kokon Shoin Press. (In Japanese) Ochi, S., Rahman, N.M., Kakiuchi, H.(1991): A study on flood risk evaluation in Bangladesh using Remote Sensing and GIS. Journal of the Japan Society of Photogrammetry and Remote Sensing. 30(6): 34-38. Setojima, M., Akamatsu, Y.(1990): Attempts towards the high utilization of the disaster prevention data extracted by image analysis. Journal of the Japan Society of Photogrammetry and Remote Sensing. 29(4): 4-15. Shimada,M., Isoguchi,O. (2002): JERS-1 SAR Mosaics of Southeast Asia Using Calibrated Path Images. International Journal of Remote Sensing. 23(1): 507–1526.

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Smith, L.C.(1997): Satellite remote sensing of river inundation area, stage and discharge; A review. Hydrological Process.11: 1427-1439. Shon,H.G., Song,Y.S., Kim,G.H., (2005): Detecting Water Area During Flood Event from SAR Image. Lecture Notes in Computer Science: 771-780. Ta,T.K.O., Nguyen,V.L., Tateishi,M., Kobayashi,I. and Saito,Y. (2001): Sediment facies and diatom and foraminifer assemblages of Late Pleistocene-Holocene incised-valley sequence from the Mekong River Delta, Bentre Province, Southern Vietnam: the BT2 core. Journal of Asian Earth Sciences. 20: 83–94. Ta, T.K.O., Nguyen, V.L., Tateishi, M., Kobayashi, I., Tanabe, S., Saito,Y. (2002): Holocene delta evolution and sediment discharge of the Mekong River, southern Vietnam. Quaternary Science Reviews.21(16–17): 1807–1819. Tanabe, S., Ta, T.K.O., Nguyen, V.L., Tateishi, M., Kobayashi, I. and Saito, Y. (2003): Delta Evolution Model Inferred from the Holocene Mekong Delta, Southern Vietnam. In F. H. Sidi, D. Nummedal, P. Imbert, H. Darman, H. W. Posamentier (eds.) Tropical Deltas of Southeast Asia—Sedimentology, Stratigraphy, and Petroleum Geology—SEPM Special Publication. 76: 175–188. Townsend, P.A., Walsh, S.J.(1998): Modeling flood plain inundation using integrated GIS with radar and optical remote sensing. Geomorphology. 21(98): 295-312. Van, N.L., Ta, T.K.O., Tateishi, M., Kobayashi, I., Saito, Y. (2000): Late Holocene depositional environments and coastal evolution of the Mekong River Delta, Southern Vietnam. Journal of Asian Earth Sciences. 19: 427–439.

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In: Geomorphology and Plate Tectonics Editors: D. M. Ferrari, A. R. Guiseppi

ISBN: 978-1-60741-003-4 © 2009 Nova Science Publishers, Inc.

Chapter 3

WHY ARE ROCK GLACIERS MORE OR LESS PROMINENT IN HIGH MOUNTAINS? Sébastien Monnier* Department of Geography, Paris, Val de Marne University; Laboratory of Physical Geography, CNRS, France

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ABSTRACT In this chapter, the spatial prominence of rock glaciers is analyzed from two study areas, the Vanoise Massif, Northern French Alps, and the Chandi-Gorakh Himal, Western Nepal. Data are collected using public remote sensing techniques (PhotoExploreur© and Google EarthTM). In the Vanoise Massif, a spatial unit-based method is performed in order to differentiate units with rock glaciers and units without rock glaciers. In the Chandi-Gorakh Himal, the distribution of the rock glaciers is confronted to the distribution of other phenomena through GIS operations. This chapter emphasizes on the influence of glacier occupation and topography on rock glacier occurrence and prominence. Rock glaciers are highlighted as post-glacial features.

INTRODUCTION Rock glaciers are common and spectacular features in high mountains [Figure 1] and they can be defined according to morphology, internal structure, and dynamics. Indeed, rock glaciers are voluminous debris tongues with surface flow-like features [Capps, 1910; Wahrhaftig & Cox, 1959]. They contain, or contained when relict, ice underground [Haeberli et al., 2006] that can be of periglacial as well as of glacial origin [Haeberli & Vonder Mühll, 1996; Clark et al., 1998]: both types constitute permafrost [Washburn, 1979]. They move, or moved when inactive, under the effect of permafrost creep, i.e. steady-state gravitational deformation of debris made cohesive by ice [Haeberli et al., 2006]. Because of long-term

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debates about their internal structure [e.g., Whalley & Martin, 1992; Barsch, 1996], a great part of the renown of rock glaciers is due to case studies such as the one of the Galena Creek Rock Glacier, Wyoming [Potter, 1972; Barsch, 1987; Potter et al., 1998]. Statistical studies of rock glaciers on a regional scale are, however, frequent [e.g. White, 1979; Hassinger & Mayenski, 1983; Chueca, 1992; Guglielmin & Smiraglia, 1998; Humlum, 2000; Baroni et al., 2004; Brenning & Trombotto, 2006; Johnson et al., 2007] and important because they highlight conditions of rocks glacier occurrence. The latter is a major scientific topic because of the increasing interest in indicators of global change, permafrost degradation and natural hazards relating to recent climate warming [Dramis et al., 1995; Harris et al., 2001; Kääb et al., 2007; Delaloye et al., 2008].

Figure 1. Set of rock glaciers in the Vanoise Massif, Northern French Alps: the Lanserlia-Plan du Lac rock glaciers. The upper zone elevation is ca. 2650 m and the lowest front elevation, to the right on the picture, is 2350 m. The site is NW-facing. In their lower part, the rock glaciers are covered by grass but may still contain ice. Photograph by S. Monnier (November 2007).

Rock glaciers are often prominent in the landscape and have a strong morphological identity; hence they are very different from debris-covered glaciers. The boundaries of the first with the surrounding terrain are clear; the ones of the latter are not. Rock glaciers have a very special puffy appearance while debris-covered glaciers have a much flatter, even depressed surface. Above all, the surficial features of rock glaciers are notably and geometrically laid out: parallel in the upper zone, ridges and furrows become embedded and *

Correspondence to: Sébastien Monnier, Université Paris 12-Val de Marne, Département de Géographie, UFR Lettres et Sciences Humaines, 61 avenue du Général de Gaulle, F-94000 Créteil. Mail to: [email protected].

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concentric in the distal part. In comparison, the surface of debris-covered glaciers is chaotic: hummocks, depressions and crevasses have no spatial organization [Iwata et al., 2000]. The sum of these morphological characteristics can also be used to avoid the confusion between rock glaciers and morphologically close deposits such as rockslides [Fort, 2003]. On the whole, rock glacier distribution-related studies have highlighted the influence of regional climate [e.g. Guglielmin & Smiraglia, 1998], local topoclimatic conditions especially aspect [e.g. Baroni et al., 2004], and structural context [e.g. Chueca, 1992]. However, methods taking account of both occurrence and non-occurrence of rock glaciers in the same study area are rare. Only the work by Johnson et al. [2007] in the Lemhi Range, USA, was based on comparison between valleys with and without rock glaciers; their results emphasized the effect of topographic shading, lithology, relief, aspect, and elevation. In this chapter, the key question is: why are there rock glaciers in some locations and not in others? The goal is to show that analyses based on such a question can give new insights into the rock glacier spatial prominence of two different areas: the Vanoise Massif, Northern French Alps, and the Chandi-Gorakh Himal, Western Nepal, studied respectively with statistical and GIS methods.

STUDY AREAS

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Vanoise Massif The Vanoise Massif is located in the Northern French Alps [Figure 2], between 45°06’ and 45°37’North, and 6°28’ and 7°11’East. It is a high mountain area, with crest lines frequently higher than 3000 m and many summits higher than 3500 m [Figure 3]. Strictly speaking, the Vanoise Massif is bounded to the North by the Isère valley and to the south by the Arc valley; however, in this chapter, interesting areas close to the South and to the East have been included. The glacier occupation in the area is quite important so that it is the third glacier-occupied area in the Northern French Alps. The glacier occupation was quite total during the Last Glacial Maximum (LGM) [Onde, 1938; Vivian, 1975]. The geological structure of the Vanoise Massif is highly complex with three great zones, from the West to the East: the external briançonnaise zone, known as carboniferous zone, the internal briançonnaise zone, and the so-called ‘Schistes lustrés’ zone [Debelmas & Desmons, 1997]. Therefore, the lithology is much varied. A synthetic sum of the lithology highlights the six types as follow: plasterstones; carbonate rocks – limestones, dolomites, and marbles (Mesozoic); ‘Schistes lustrés’ and ophiolitic rocks (Cretaceous); gneiss and micaschists of the metamorphic basement with volcanic materials (Paleozoic); schists and sandstones of the carboniferous zone; and quartzites (Permian-Triassic and Triassic). The climate is a mid-latitude mountain climate both influenced by maritime contexts (Atlantic Ocean, Mediterranean Sea) and internal position in the Alpine Range. Totals of precipitation are spatially contrasted due to complex local circulations. Data from valley stations of the Meteo France network show precipitation to be between 700 and 1100 m/yr. However, in the high-altitude areas of the massif, precipitation are between 1500 and 2000, even higher than 2000 mm/yr [Voiron, 1983; Kaiser, 1987; Morel et al., 1998]. According to station position and aspect, the mean annual air temperature at 1500 m is between 5 and 7°C.

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Using a −0.6°C/100 m temperature decreasing gradient [Douguédroit & de Saintignon, 1970] and data from several valley stations, the −2°C isotherm is located between 2650 and 2850 m [Monnier, 2006].

Figure 2. Location sketches of the two study areas

The Vanoise Massif is the area with the greatest number of rock glaciers in the Northern French Alps. Some of them were previously studied, especially the Lanserlia-Plan du Lac rock glaciers by Kaiser [1975, 1983] and Monnier et al. [2008]. This chapter presents prominent results from the first study related to the total number of rock glaciers of the Vanoise area [Monnier, 2006].

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Figure 3. Topographical characteristics of the Vanoise Massif. Elevation in meters a.s.l. The study area is depicted with the thick dark line.

Chandi-Gorakh Himal The Chandi-Gorak Himal is located in the North-Western Nepal Himal [Figure 2], part of the so-called ‘far western’ Nepal, between latitudes of 29°50’ to 30°25’ North, and between longitudes of 81°53’ to 82°31’ East. Tibetan slopes outside the border crest were included. The Chandi-Gorakh Himal is a very high, remote and hardly accessible mountain area. The crest lines are for their most part ca. 5500 m [Figure 4]. However, in some parts of the study area, especially in the northern part, altitudes rise much higher than 6000 m. The two major valleys are the Dojamchour Khola, and the Take Khola that represents the south-eastern boundary of the study area. Large cirque and valley glaciers are present on the Tibetan northfacing slopes of the study area. Glaciers in the Chandi-Gorakh Nepal are much less

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prominent. According to Asahi & Watanabe [2004]†, the equilibrium line altitude (ELA) of glaciers in the Chandi Himal is between 5000 and 5500 m, and was between 4200 and 4500 m during the LGM; the area was thus widely englaciated. Data about the geological structure and the climate of the Chandi-Gorakh Himal are rare. According to the work by Upreti & Le Fort [1999], the western part of the area belongs to the Higher Himalaya crystalline nappe, and the eastern part of the area belongs to the Higher Himalaya Leucogranite zone. Both of them are located North to the Main Central Thrust. The Chandi-Gorakh Himal belongs to the dry Nepal. According to the works by Baidya [2007] and Ichiyanagi et al. [2007], annual precipitation in North-Western Nepal is between 500 and 1000 mm. There are no accurate data related to temperatures in the Chandi-Gorakh Himal. In Jumla, located at 2300 m, 75 km South to the study area, the mean annual temperature is 12°C [Devkota et al., 2006].

Figure 4. Topographical characteristics of the Chandi-Gorakh Himal. Elevation in meters a.s.l. The study area is depicted with the thick dark line. †

The paleoclimate reconstructing by Asahi & Watanabe [2004] is the only scientific work directly related to the study area.

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Studies related to rock glaciers in the Himalaya Mountains started in the early 1990’s [Jakob, 1992]. In Nepal, rock glaciers studies have been concentrated in the central and eastern parts of the country, especially in the Khumbu Himal [Barsch & Jakob, 1998; Fukui et al., 2007] and in the Kanchenjunga Himal [Asahi, 1999]. Regmi [2006] devoted a part of his PhD thesis to the rock glaciers of the Sisne Himal, East to the Chandi-Gorakh Himal. Before the present chapter, the rock glaciers of the Chandi-Gorakh Himal had never been studied, while they seem to form one of the biggest and most striking sets of rock glaciers throughout the world. In fact, the development of Google EarthTM since 2005 has permitted to explore and study with free remote sensing techniques such hardly accessible areas, with an accuracy depending upon the quality of imagery data. This quality of imagery data quite influenced the demarcation of the study area.

METHODS

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Data Acquisition: Identification and Description of the Rock Glaciers According to field characteristics, nature and precision of the available imagery data, the surveying techniques differed from one study area to another. In the Vanoise Massif, Northern French Alps, field access is easy, several missions of aerial photographs were available, and the PhotoExploreur© software (developed by the BAYO firm and the National Geographic Institute, France) provides, for low cost, large coverage and high resolution (0.5 m) orthophotographs with a 50 m-grid resolution, 1 m-precision digital elevation model. PhotoExploreur© includes accurate measurement and data storage functions. Moreover, the Google EarthTM imagery in the Vanoise Massif does not have high enough resolution for professional surveys. On another hand, the extended study of such a remote and hardly accessible area as the Chandi-Gorakh Himal is permitted by the very good imagery data provided in parts of the North-Western Nepal by Google EarthTM. Therefore, the rock glaciers of the Vanoise Massif were identified using field sessions, series of aerial photographs from ca. 1950 to ca. 2000, and the PhotoExploreur© software. The rock glaciers of the ChandiGorakh Himal were identified thanks to the use of Google EarthTM only. Rock glaciers were identified according to the following criteria of recognition. Rock glaciers are made up of great volumes of superficial deposits, at the foot of rocky walls or in glacier forefield terrains; they are clearly delineated and have, in particular, a steep frontal slope; last, they exhibit geometrically laid out flow-like features. The latter compose, in the most achieved cases, the typical and so-called, depending upon authors and perception, porridge-like, lava-like or noodles-like appearance. On another hand, some rock glaciers may have only a few ridges and a smoother appearance. In the same manner, the description techniques of the rock glaciers depended of field, data and research context characteristics. The Vanoise Massif has a quite limited number (few tens) of rock glaciers and was studied over the long time of a PhD thesis [Monnier, 2006]. The rock glaciers were surveyed as polygons using the measurements functions of the PhotoExploreur© software. Quantitative parameters such as minimum and maximum altitudes, area, length of the rock glacier, and altitude of the surrounding rock walls were recorded and stored into a database. Additionally, detailed qualitative parameters were

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recorded. The morphological appearance parameter set the rock glaciers in two classes: intact rock glaciers, and decayed rock glaciers. The aspect parameter was measured according to the aspect of the rock glacier slope system, i.e. the surrounding rock walls added to the rock glacier downslope; the recorded value was degrees clockwise and converted into 45°amplitude aspect class. The morphological transition in the upper zone of the rock glacier parameter can have two values. Either rock glaciers are covered by the upslope feature; either they extend the topography and the sedimentology of the upslope feature. The upslope feature can be: glacier, debris-covered glacier, morainic feature, talus slope, or another rock glacier. However, some morphological transitions could not be identified because of bad observation conditions on the photographs or because of individual morphological complexity. Finally, the lithology of the rock walls above the rock glacier parameter was recorded into a table of lithological type occurrence per rock glacier using detailed geological maps of the area. On another hand, the Chandi-Gorakh Himal has a great number of rock glaciers (few hundreds) and was studied with the use of Google EarthTM only over a short time. The rock glaciers of this area were stored as polygons in a kml file then converted into a GIS-designed shape file. Description parameters of the rock glaciers especially geometrical parameters were acquired using GIS automatic treatments and a SRTM digital elevation model, and stored into a database. All the rock glaciers identified in the Chandi-Gorakh Himal, despite of a large elevation interval (see results), appear as intact, well preserved features. Moreover, because of the great number of rock glaciers and frequent indistinct observations between rock glaciers upper zones and rock walls on Google EarthTM, the morphological transition in the root zone was not recorded. Because of no fine-scale geological data, the lithology of the walls surrounding every rock glacier could neither be recorded. However, geological zones were integrated into the occurrence analysis (see below).

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Analysis of the Rock Glacier Occurrence Two different sets of techniques were used in the two study areas, respectively, for analyzing the occurrence of rock glaciers. The same question was nevertheless used as a guide: why are there rock glaciers in some places and not in others? In the Vanoise Massif, the database built for the description of the rock glaciers (db#1) was used to highlight statistical regularities in the location of rock glaciers. These statistical regularities were the basis for hypotheses about the differential location of rock glaciers: if rock glaciers are for the most part located in sites characterized by x, then one might suppose that rock glaciers tend to be in sites characterized by x and not to be in sites not characterized by x, where x is an environmental parameter. A second database (db#2) was created for comparison of spatial units with rock glaciers and spatial units without rock glaciers. Because of the need to attach importance to crest lines and to get spatial units with constant aspect, a slope unit-based method was preferred to a grid-based method. Corries are adapted to such criteria, are moreover convenient therefore were chosen. The method was run in the southern part of the Vanoise area, where all the corries (79) were identified and formed the spatial units of the db#2 database. The parameters of db#2 were defined after the statistical regularities highlighted in the first analysis step. Corries were surveyed as polygons in the PhotoExploreur© software. The db#2 database was then analyzed using two complementary techniques: hypothesis tests and standardized Principal Components Analysis (PCA).

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Hypothesis tests were used in order to find significant statistical differences between corries with rock glaciers and corries without rock glaciers. Thus, hypotheses of differential location where formulated as null hypotheses (H0): x is not significantly different between corries with and without rock glaciers, where x is the environmental parameter. In this chapter χ²-test was used for testing null hypotheses based on qualitative parameters, and F-test was used for testing null hypotheses based on continuous quantitative parameters. Principal Components Analysis (PCA) was used in order to produce factorial axes and plans where the rock glacier parameter could be grouped with or opposed to other parameters. PCA was used for testing hypotheses based both on qualitative and quantitative parameters. Qualitative parameters were quantitatively coded before run in PCA. The use of two different and complementary techniques (hypothesis tests and PCA) was guided by the will of using both uni- and multivariate statistical analysis tools, and by the concern for the limited reliability of the hypothesis tests. Especially the F-test is a parametrical test thereby quite influenced by nonnormal statistical distributions. The sizes of the studied groups were sufficient to assess normal distributions (central boundary limit [Béguin, 1979]) however the complementary use of PCA reduced the risks of misinterpretations and hasty conclusions. In the Chandi-Gorakh Himal, the spatial distribution of the rock glaciers was confronted to the distribution of phenomena studied with GIS techniques. Previous hypotheses or results in the Vanoise area or in the literature [Chueca, 1992; Johnson et al., 2007] about the influence of several phenomena on rock glacier distribution led to focus on glaciers, debriscovered glaciers, lithological zones, specific topographic features, and solar radiation. Glacier and debris-covered glacier spatial distributions were recorded from Google EarthTM survey sessions. Lithological zones were mapped after the work by Upreti & Le Fort [1999]. Specific topographic features were extracted from the SRTM data thanks to topographic modeling tools. Finally, the annual amount of solar radiation was extracted from the SRTM data thanks to solar analysis tools. The occurrence analysis was then based on GIS mapping and basic spatial analysis steps.

RESULTS Rock Glaciers Main Characteristics and Spatial Prominence In the Vanoise area (~2200 km²), about 160 rock glaciers were identified. Fifty percent of the rock glaciers were classified as intact and 50% as decayed. According to their minimum elevation, the rock glaciers take place between 1700 and 2900 m [Table 1]. Fifty percent of the rock glaciers are between 2240 and 2660 m, and 80% are between 2060 and 2770 m. The mean area of the rock glaciers is 0.116 km², with values ranging from 0.010 to 0.630 km². The total area of the rock glaciers is 18.2 km², i.e. less than 1% (0.8%) of the overall study area. The mean length of the rock glaciers is 470 m, with values ranging from 110 m to 1390 m. In the Chandi-Gorakh area (~2500 km²), about 420 rock glaciers were identified. As mentioned above, all the rock glaciers were described as intact features, very well preserved without or with unimportant vegetation cover on their surface – which do not mean that all of them would be active features. According to their minimum elevation, they take place between 3850 and 5690 m [Table 1], which is a quite large interval, but 50% are between

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4690 and 5085 m (400 m-interval, as in the Vanoise area), and 80% are between 4480 and 5270 m (800 m-interval, hardly more than in the Vanoise area). However, the minimum value-D1 value interval is ca. 600 m in the Chandi-Gorakh Himal while only ca. 300 m in the Vanoise Massif; the D9 value-maximum value interval is ca. 400 m in the first while less than 200 m in the latter. Then the larger overall range of elevation in the Chandi-Gorakh Himal is mainly explained by the presence of exceptional units at the two opposites of the statistical distribution. The mean area of the rock glaciers in the Chandi-Gorakh Himal is 0.312 km², with values ranging from 0.007 km² to 4.330 km². The total area of the rock glaciers is 131 km², i.e. 5.3% of the overall study area. The mean length of the rock glaciers is 930 m, with values ranging from 125 m to 4.6 km. In average, the rock glaciers of the Chandi-Gorakh Himal are twice to three times bigger than the rock glaciers of the Vanoise Massif; however their size range is also larger. The most striking is the difference of spatial prominence from one area to the other: rock glaciers are almost seven times more prominent in the ChandiGorakh Himal (occupation ratio = 5.3%) than in the Vanoise Massif (occupation ratio = 0.8%). In conclusion, with respect to spatial quantitative criteria, the rock glaciers of the Vanoise Massif are common but not very prominent features while the rock glaciers of the Chandi-Gorakh Himal are very prominent features. Table 1. Quantitative descriptors of the rock glaciers of the Vanoise Massif (VM) and the rock glaciers of the Chandi-Gorakh Himal (CGH)

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Min. elevation (m)

Max. elevation (m)

Area (km²)

Length (m)

VM

CGH

VM

CGH

VM

CGH

VM

CGH

Mean

2435

4881

2562

5126

0.116

0.312

466

931

S.d.

275

309

250

313

0.011

0.520

248

698

Minimum

1702

3851

2005

4188

0.010

0.007

114

124

Maximum

2956

5694

3085

6142

0.626

4.332

1390

4618

Q1

2240

4686

2400

4954

0.048

0.071

290

477

Q2

2473

4888

2590

5139

0.083

0.137

410

731

Q3

2658

5085

2755

5333

0.145

0.313

586

1142

D1

2061

4476

2198

4668

0.028

0.036

215

306

D9

2769

5270

2880

5500

0.243

0.658

805

1714

Occurrence Analysis Statistical Regularities in the Vanoise Massif The highlighted statistical regularities in the location of the rock glaciers of the Vanoise Massif are statistical regularities of altitude of the surrounding crests, aspect, lithology, and morphological context. The statistical regularities of altitude, aspect, and lithology are simple statistical regularities. First, most of the rock glaciers are located under relatively low crests. Fifty percent of the rock glaciers are located at the foot of crests which mean elevation is in the

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2600-2900 m interval, and the 200 m-interval modal class (more than a third of the rock glaciers) is [2800-3000]. Moreover, most of the rock glaciers are located in North- (28%), NW- (26%), and W- (21%) facing sites. Only 4% of the rock glaciers are located in NEfacing sites. Rock glaciers located in SW-, S-, and SE-facing sites are very rare (3%). Finally, most of the rock glaciers are located at the foot of carboniferous schists and sandstones (30.5%) and limestones (28%) walls. However, taking account of the areas of the lithological types, high densities of rock glaciers are found in quartzites (0.19 rock glaciers/km²) and in limestones (0.17 rock glaciers/km²). The other lithological types display lower rock glacier densities (carboniferous schists and sandstones: 0.08 rock glaciers/km²; gneiss and micaschists of the metamorphic basement: 0.06 rock glaciers/km²; ‘Schistes lustrés’: 0.03 rock glaciers/km²; plasterstones: 0.01 rock glaciers/km²). The statistical regularity of morphological context is highlighted from several statistical and mapping-based observations. Indeed, most Vanoise rock glaciers are located in deglaciated (not unglaciated) terrains. Such an assessment is based on three observations. First, the rock glaciers are concentrated in the peripheric-external (western) sectors of the study area, which are the less glaciated and the ones where – undoubtly – glaciers started to retreat first. Furthermore, the distribution of intact and decayed rock glaciers according to internal and external sectors of the study area significantly differs from a random distribution (computed χ²-value=23.27; significance level=0.95; 1 degree of freedom; region of rejection of H0: χ²>3.84). Therefore, the intact rock glaciers tend to be located near the highest summits and the glaciated surfaces while the decayed rock glaciers tend to be located in lower massifs without glaciers. Third, and above all, 40% of the rock glaciers extend a glacial context, i.e. a glacier, a debris-covered glacier or morainic materials. By neglecting the rock glaciers covered at their upper zone by another deposit and those for which observation is not accurate enough for diagnostic, this proportion rises to 70%.

Differentiating with- and without-Rock Glaciers Corries in the Vanoise Massif: Constitution of the Corrie-Based Database and Formulation of the Null Hypotheses Following the highlighted statistical regularities, the analysis was based on the preliminary global hypothesis for differential location of rock glaciers: rock glaciers in the Vanoise Massif tend to be in specific corries and not in others according to the mean altitude of the corrie crests, the aspect of the corrie, the lithology of the corrie walls, and the glacier occupation. Thus, the hypothesis can also be expressed as follow: are crests altitude, aspect, lithology, and glacier occupation significantly different between corries with rock glaciers and corries without rock glaciers? The db#2 database was built according to such a question. A number of parameters were chosen to describe the corries: area, mean altitude of the crests, aspect expressed as coding‡, lithology expressed as coding§, total rock wall occupation ratio**, specific rock wall occupation ratio††, additionally occurrence or absence of faults and thrusts in the walls‡‡, glacier occupation ratio§§, and finally number of rock glaciers and rock glacier ‡

Occurrence of aspect class = 1; absence = 0 Occurrence of one lithological type = 1; of two = 0.5 for each one; of three = 0.33 for each one, etc ** Overall walls area/corrie area †† Walls area per lithological type/corrie area ‡‡ Expressed as coding: 1 or 0 §§ Glaciated area/corrie area §

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occupation ratio***. One must remarks that, in PCA, the aspect, as well coded in numbers (discrete parameter) as expressed in a true value in degrees (continuous parameter) is a ‘circular’ parameter without relevance in an analysis based on correlation. Thus, the aspect was not included in PCA operations. In the same way, the total rock wall occupation ratio was not included because of the information redundancy it would have made added to the specific rock wall occupation ratios. In the db#2 database, 30 corries have at least one rock glacier and 49 corries do not have any rock glacier. The number of rock glaciers in the group of the with-rock glaciers corries is 47. The mean number of rock glacier per corrie in this group is 1.6. Four null hypotheses were formulated. (1) The mean elevation of the crests is not significantly different between corries with and without rock glaciers. (2) The aspect is not significantly different between corries with and without rock glaciers. (3) The walls structure (lithology, faults) is not significantly different between corries with and without rock glaciers. (4) The glacier occupation is not significantly different between corries with and without rock glaciers. Table 2. Expected (random) and observed distributions of corries with and without rock glaciers according to aspect, lithology and fault/thrust occurrence

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Expected distribution

Aspect

Walls

***

Observed distribution

Corries with rock glaciers

Corries without rock glaciers

Corries with rock glaciers

Corries without rock glaciers

N

4.94

8.06

5

8

NE

3.80

6.20

2

8

E

2.66

4.34

4

3

SE

3.04

4.96

1

7

S

2.66

4.34

2

5

SW

2.66

4.34

5

2

W

6.08

9.92

7

9

NW

4.18

6.82

4

7

Limestones

2.46

4.03

3.33

3.16

‘Schistes lustrés’

12.53

20.47

10

23

Gneiss and micaschists

4.49

7.34

1

10.83

Carboniferous schists and sandstones

6.90

11.26

10.83

7.33

Quartzites

3.60

5.89

4.83

4.66

Fault/thrust: yes

11.01

18.99

13

17

Fault/thrust: no

17.99

31.01

16

33

Rock glaciers area/corrie area

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Differentiating with- and without-Rock Glaciers Corries in the Vanoise Massif: Results of the Hypothesis Tests The χ² tests [Tables 2 & 3] show that the distribution of corries with and without rock glaciers according to aspect classes is not significantly different from a random distribution (the computed χ²-value is not in the region of rejection of the null hypothesis). Therefore the aspect is not able to statistically differentiate the group of the with-rock glaciers corries and the group of the without-rock glaciers corries. This is a quite surprising result: the preference of rock glaciers to north-facing sites in mid-latitude mountains of the northern hemisphere is a quite common and assumed fact in the literature [White, 1979; Barch, 1996; Humlum, 2000; Baroni et al., 2004]. Additionally, the results of the χ² test can be illustrated by the diagram that depicts the distribution of the corries according to aspect [Figure 5]: the form of the with-rock glaciers corries distribution is quite the same as the form of the overall corries distribution. Table 3. Results of the χ² tests of with- and without-rock glaciers corries distributions (values in the region of rejection are in bold characters) Test of the distributions: According to aspect classes

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According to lithological types According to occurrence/absence of faults and thrusts

Significance level 0.95

Degrees of freedom 7

Region of rejection of H0 > 14.07

0.95

4

> 9.49

9.98

0.95

1

> 3.84

0.90

Computed χ² 8.50

Figure 5. Distribution of the overall, with-, and without-rock glaciers corries of the southern Vanoise Massif according to aspect

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The χ² tests [Tables 2 & 3] show that the distribution of corries with and without rock glaciers according to lithological types is significantly different from a random distribution (the computed χ²-value is in the region of rejection of the null hypothesis). Therefore, lithology is able to statistically differentiate the group of the with-rock glaciers corries and the group of the without-rock glaciers corries. The computed χ²-value seems to be related to the following facts. First, the occurrence of gneiss and micaschists in the without-rock glaciers corries group is abnormally higher than in the with-rock glaciers corries group. Secondly, the occurrence of carboniferous schists and sandstones in the with-rock glaciers corries group is abnormally higher than in the without-rock glaciers corries group. Moreover, the χ² tests show that the distribution of corries with and without rock glaciers according to occurrence/absence of faults or thrusts in the rock walls is not significantly different from a random distribution (the computed χ²-value is not in the region of rejection of the null hypothesis). Therefore faults and thrusts in rock walls are not more prominent in one group than in the other. Table 4. Parameters means of the corries with and without rock glaciers and results of the F-tests (for a significance value of 0.95, with 1 degree of freedom between groups, 77 degrees of freedom within groups and a region of rejection of H0 corresponding to F > 3.96; values in the region of rejection are in bold characters) Corries with rock glaciers

Corries without rock glaciers

Computed F-value

Corrie area (km²)

2.13

3.51

6.76

Crests mean altitude (m)

2931

3088

9.85

Limestones wall occupation ratio

0.03

0.02

0.03

‘Schistes lustrés’ wall occupation ratio

0.12

0.11

0.05

Gneiss and micaschists occupation ratio

0.01

0.06

5.50

Carboniferous schists and sandstones wall occupation ratio

0.06

0.04

1.07

Quartzites wall occupation ratio

0.04

0.02

1.32

Total rock wall occupation ratio

0.264

0.256

0.06

Glacier occupation ratio

0.03

0.19

19.14

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Parameter

wall

The F-tests [Table 4] show several significant differences between the means of the withrock glaciers corries group and the means of the without-rock glaciers corries group. The corries with rock glaciers are significantly smaller (mean area: ca. 2.1 km²) than the corries without rock glaciers (mean area: ca. 3.5 km²). The crests of the corries with rock glaciers are significantly lower (mean altitude: ca. 2900 m) than the crests of the corries without rock glaciers (mean altitude: ca. 3100 m). Still more significantly, the glacier occupation ratio of the corries with rock glaciers is lower (mean: 3%) than the glacier occupation ratio of the corries without rock glaciers (mean: 19%). However, for the total rock wall occupation ratio, and for most specific rock wall occupation ratios, the differences between the means of the with-rock glaciers corries group and the means of the without-rock glaciers corries group are not significant. Only the gneiss and micaschists wall occupation ratio is significantly lower in

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Why Are Rock Glaciers More or Less Prominent in High Mountains?

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the corries with rock glaciers (1% of the corrie area) than in the corries without rock glaciers (6% of the corrie area). Such a result supports the contribution of these rocks to the χ²-value in testing the distribution of the corries according to lithological types (see above).

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Differentiating with- and without-Rock Glaciers Corries in the Vanoise Massif: Results of the Principal Components Analysis (PCA) The results obtained from the standardized PCA supports the results obtained from the hypothesis tests. The percentage of the variance explained by the four first axes of the PCA is 65% [Table 5]. The rock glacier occupation ratio is well represented on the first PCA-axis (F1, explains 26% of the variance) [Table 6]. F1 opposes, on one hand, the rock glacier occupation ratio, the carboniferous schists and sandstones wall occupation ratio, and the quartzites wall occupation ratio to, on the other hand, the mean altitude of the crests, the corrie area, and the glacier occupation ratio. Plotting the parameters on the correlation circles of the F1-F2, F1-F3, and F1-F4 factorial plans [Figure 6] allows good understanding of the parameters groups and oppositions. Thus, the PCA differentiate, on one hand, corries with rock glaciers, with quartzites and carboniferous schists and sandstones walls and, on the other hand, corries with elevated crests, of great dimensions, and with a high glacier occupation ratio. Compared with the results of the hypothesis tests, the PCA shows the association of rock glaciers and quartzites walls. The cause of this new result may be the expression of the rock glacier parameter no more as an occurrence but as an areal phenomenon. Nevertheless, a detailed examination of the data highlights quite awesome corries. For example, the contribution of the so-called ‘Arplane’ corrie to the F1 axis is 15%. This is disproportionate in comparison with the other corries. In point of fact, in the Arplane corrie, the rock glacier occupation ratio is 75% and the quartzites wall occupation ratio is 33%. Eliminating this corrie from the data before running PCA modifies the results: rock glaciers and quartzites walls are no longer grouped. The results must, thus, be interpreted cautiously. GIS-Based Results in the Chandi-Gorakh Himal Although rock glaciers are very prominent in the Chandi-Gorakh Himal, they are not everywhere [Figure 7]. The distribution of the rock glaciers vs. the distribution of the other studied phenomena is significant and helps to understand rock glacier occurrence laws. First, the density of rock glaciers inversely correlates the density of glaciers [Figures 7 and 8]. In the Chandi-Gorakh Himal, glaciated surfaces represent about 18% of the overall area but they are concentrated in the form of very large glaciers on the Tibetan slopes, where rock glaciers are little prominent. Moreover, the number of rock glaciers strictly contiguous to a glacier or a debris-covered glacier is 19 (4.5% of the total number of rock glaciers) and the number of rock glaciers less than 200 m from a glacier or a debris-covered glacier is 72 (17%). Debriscovered glaciers are not prominent (24 units, 1.5% of the study area). However 10 of them show clear and sometimes widespread morphological signs of evolution into rock glaciers: typical steep and fine-grained front, transverse ridges and furrows forming in the distal part. Such observations are quite exceptional. At the end, and as in the Vanoise Massif, rock glaciers tend to be in deglaciated areas, considering the fact that the Chandi-Gorakh Himal was englaciated during the Last Glacial Maximum (LGM). Indeed, reconstructed ELAs for the LGM in the Chandi Himal by Asahi & Watanabe [2004] are between 4200 and 4500 m, i.e. approximately equal to the first decile of the minimum altitude of the rock glaciers.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

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Figure 6. Results of the PCA through the corries of the southern Vanoise Massif: plotting of the parameters on the F1-F2, F1-F3, and F1-F4 factorial plans. AREA: area. CSS: carboniferous schists and sandstones wall occupation ratio. ELEV: mean elevation of the crests. FAULTS: fault and thrust occurrence. GL: glacier occupation ratio. GNMIC: gneiss and micaschists wall occupation ratio. LIMES: limestones wall occupation ratio. RG: rock glacier occupation ratio. QZ: quartzites wall occupation ratio. SL: ‘Schistes lustrés’ wall occupation ratio.

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Table 5. Principal Components Analysis: eigenvalues and quality of representation of the axes. Values in bold characters are higher than the 100/n (with n number of parameters) critical point of representation

Eigenvalue % Variance Cumulated %

F1 2.557 25.567 25.567

F2 1.520 15.201 40.768

F3 1.276 12.758 53.526

F4 1.120 11.204 64.730

F5 0.962 9.618 74.348

F6 0.818 8.183 82.531

F7 0.714 7.137 89.668

F8 0.596 5.961 95.629

F9 0.298 2.976 98.605

F10 0.139 1.395 100.000

Table 6. Principal Components Analysis, selected axes F1 to F4: coordinates of the parameters on the axes (Coord.), quality of representation of the parameters by the axes (QR) and contribution of the parameter to the axes (% Contrib.). Values in bold characters are higher tan the 100/n (with n number of parameters) critical point of representation F1

F2

F3

F4

Coord.

QR

% Contrib.

Corrie area

0.518

0.268

10.479

-0.111

0.012

0.805

-0.207

0.043

3.361

-0.407

0.165

14.751

Crests mean altitude

0.871

0.759

29.699

0.159

0.025

1.664

0.038

0.001

0.114

0.104

0.011

0.958

Limestones wall occupation ratio

0.064

0.004

0.162

0.036

0.001

0.087

0.637

0.406

31.854

0.650

0.422

37.664

Gneiss and micaschist walls occupation ratio

0.172

0.030

1.161

-0.507

0.257

16.933

0.388

0.150

11.778

-0.422

0.178

15.898

Quartzites wall occupation ratio

-0.468

0.219

8.551

0.281

0.079

5.180

0.320

0.102

8.012

-0.428

0.183

16.319

Carboniferous schists and sandstones wall occupation ratio

-0.522

0.273

10.675

-0.470

0.221

14.514

-0.390

0.152

11.949

0.369

0.136

12.121

‘Schistes lustrés’ wall occupation ratio

0.427

0.182

7.128

0.645

0.415

27.330

-0.447

0.200

15.676

0.101

0.010

0.916

Fault or thrust occurrence

0.021

0.000

0.018

0.558

0.312

20.507

0.329

0.108

8.497

-0.035

0.001

0.110

Glacier occupation ratio

0.644

0.415

16.246

-0.263

0.069

4.551

0.298

0.089

6.962

0.051

0.003

0.229

Rock glacier occupation ratio

-0.637

0.406

15.880

0.358

0.128

8.429

0.151

0.023

1.797

-0.108

0.012

1.034

Coord.

QR

% Contrib.

Coord.

QR

% Contrib.

Coord.

QR

% Contrib.

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Figure 7. Spatial distribution of the rock glaciers, glaciers, and debris-covered glaciers of the ChandiGorakh Himal

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Figure 8. Rock glaciers density vs. glaciers density in the Chandi-Gorakh Himal

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Figure 9. Spatial distribution of the rock glaciers of the Chandi-Gorakh Himal through lithological zones

The study area comprises two lithological zones: the Higher Himalaya crystalline nappe to the West, and the Higher Himalaya Leucogranite to the East [Upreti & Le Fort, 1999][Figure 9]. The density of rock glaciers is sensibly higher in the second (in average, 0.058 km² of rock glaciers/km²) than in the first (0.046 km² of rock glaciers/km²). Considering only the non-glaciated areas, the difference is greater: 0.073 km² of rock glaciers per km² in the Higher Himalaya Leucogranite, and 0.050 km² of rock glaciers per km² in the Higher Himalaya crystalline nappe. These results tend to highlight the influence of lithology

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Figure 10. Spatial distribution of the rock glaciers of the Chandi-Gorakh Himal compared with slope modeling

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Figure 11. Spatial distribution of the rock glaciers of the Chandi-Gorakh Himal compared with profile curvature modeling

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Figure 12. Spatial distribution of the rock glaciers of the Chandi-Gorakh Himal compared with annual solar radiation modeling

78

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on the rock glacier distribution. However, the lack of rock glaciers in the southern part of the crystalline nappe zone can also be explained by topographical factors. Indeed, let us consider the results of topographic modeling and focus on the slope map [Figure 10] and the profile curvature map [Figure 11]. The slope map classically highlights areas with more or less strong slope. The profile curvature map is helpful to highlight, on one hand, U-shaped valleys and large corries, and, on the other hand, V-shaped valleys and straight slopes. The two maps show that rock glaciers concentrate in areas characterized by partitioned relief, especially corries with gently sloping bottoms surrounded by circular crests. Outside densely glaciated areas, the areas without rock glaciers correlate the areas with less partitioned relief and straight and strong slopes. Finally, topographical shading does not appear to influence the distribution of the rock glaciers [Figure 12]. The rock glaciers tend to be in open and well-lighted areas – higher latitude and altitude, U-shaped and/or large corries – rather than in shaded areas – lower latitude and altitude, V-shaped and deep and/or narrow valleys. This observation is consistent with the abundance of rock glaciers in every aspect class-facing sites, and especially with the great part of rock glaciers in south- and SW-facing sites [Figure 13]. Nevertheless, as much as the solar radiation does not influence in the whole the spatial distribution of the rock glaciers, analyses show that the solar radiation can influence the altitude of the rock glaciers. Indeed, the lowest rock glaciers (minimum altitude less than 4400 m, first decile of the statistical distribution) are for the most part located in sites with low annual amount of solar radiation, in the western part of the study area. As well, the highest rock glaciers (minimum elevation more than 5400 m, last decile of the statistical distribution) are located in sites with high annual amount of solar radiation, in the northern and most often Tibetan part of the study area.

Figure 13. Aspect of the sites occupied by rock glaciers in the Chandi-Gorakh Himal. Aspect statistics were computed from triangles of a TIN of the study area

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Why Are Rock Glaciers More or Less Prominent in High Mountains?

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DISCUSSION

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While taking account of the differences between study areas and respective applied methods as well as the sampling-induced limits of the analysis in the Vanoise area, there is a convergence of the results from both the Vanoise Massif and the Chandi-Gorakh Himal on the following main important points: 1) The inverse correlation between the rock glacier prominence and the glacier prominence is the most significant aspect. Rock glaciers are numerous, spatially prominent, in the less glaciated areas. Such a result could seem quite basic and obvious; nevertheless it is not, and anyway it had to be demonstrated. In both study areas, the less even non-glaciated areas were englaciated at least during the Last Glacial Maximum (LGM). In most cases, rock glaciers have, thus, filled the place of ancient glaciers. 2) Topographical parameters have a strong effect on the rock glacier distribution. The corries in the Chandi-Gorakh Himal are preferential places of location of rock glaciers. On the opposite, rock glaciers lack in areas characterized by straight and strong slopes. In the Vanoise Massif, the rock glaciers tend to be in the smallest corries and not to be in the largest. 3) The influence of lithology appears moderately. In the Vanoise Massif, carboniferous schists and sandstones and quartzites seem to be favorable to the presence of rock glaciers, while gneiss and micaschists from the metamorphic basement seem to not. However, the evidence of lithology-dependence of rock glaciers is not very strong. In the Chandi-Gorakh Himal, the potential effect of lithology is masked by the effect of topography. 4) The influence of topoclimatic parameters on the whole rock glacier occurrence has not been highlighted. In the Vanoise Massif, there is not any real influence of aspect on the rock glacier distribution in the corries studied. The preference of rock glaciers to west- and north-facing sites is no more than apparent and no more reflects the spatial prominence of west- and north-facing corries. In the Chandi-Gorakh Himal, there is not any real influence of topographical shading on the rock glacier distribution. However, the influence of topoclimatic parameters in this last area is perceptible at the local scale: shaded conditions can explain the existence of rock glaciers at very low altitudes. There is a strong connection between the first two points. Indeed, the partitioning of the relief into a great number of corries closely depends on the glaciation effects on the preexisting relief. Corries were shaped and especially gently sloped at their bottom by glacier erosion. Amounts of materials were deposited during deglaciation, and underground glacial dead ice may have been preserved by debris layers under permafrost conditions. The deposition of large volumes of debris in the corries may have realized in the form of large rock falls triggered by post-glacial debutressing or by geodynamic events (faults and thrusts acting, range uplift, seismic activity, especially in the Chandi-Gorakh Himal). Rock glaciers can then be considered as permafrost phenomena which amplitude is positively controlled by previous glacial context. This conclusion is to be related to the majority of rock glaciers

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extending a glacial context in the Vanoise Massif. Mostly it takes all its meaning in the Chandi-Gorakh Himal. There, the largest rock glaciers, often several kilometers in length – exceptional values in the world – clearly fill the place of previous glaciers. They start just at the foot of the rock walls and extend downslope outside the corries, and sometimes obstruct major valleys with their distal part. Furthermore, a noticeable number of debris-covered glaciers with signs of evolution into rock glaciers have been found. They lead one to seriously call into question the possible ways of transition from debris-covered glaciers to rock glaciers. The overall independence regarding to topoclimatic conditions of the ChandiGorakh Himal rock glaciers could be then explained by the potential existence of permafrost inherited from the former and decayed glaciers. In any case, the rock glaciers studied in the Vanoise Massif and in the Chandi-Gorakh Himal can be considered as the ultimate stage of a post-glacial transition sequence and, thereby, as major indicators of environmental changes, rather than indicators of present climatic conditions. Furthermore, the greater prominence and preservation of rock glaciers in the Chandi-Gorakh Himal than in the Vanoise Massif can be explained by the quite complete addition of the as known or demonstrated as positive for rock glacier occurrence environmental factors: cold and dry climate, erodable bedrock (igneous rocks, probably highly fractured, strong geodynamic context), topography split into corrie-units, and low glacier occupation. The presence of relatively very low and very high rock glaciers in the Chandi-Gorakh Himal can be explained by a large range of topographic settings and thus topoclimatic conditions, especially according to a latitudinal gradient from southern ChandiGorakh to northern Tibetan slopes.

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CONCLUSION Spatial analyses based on data acquisition through public remote sensing softwares (Google EarthTM, PhotoExploreur©), statistical and GIS treatments were employed successfully to analyze the rock glacier occurrence in the Vanoise Massif, Northern French Alps, and in the Chandi-Gorakh Himal, Western Nepal. The approach was differential: locations with and without rock glaciers were compared. In both study areas, the rock glacier occurrence and prominence are primarily controlled by glacier occupation and topography. Indeed, rock glaciers are located in completely deglaciated areas with partitioned relief much rather than in still well glaciated areas or areas little shaped by glacial erosion. Thus, rock glaciers can be considered as critical, significant, and major post-glacial features, and the two study areas as witnesses of global changes. Additionally, lithology probably has an effect on the rock glacier distribution; however, the analyses of this chapter did not highly emphasize it. Topoclimatic factors do not appear as globally consequent, which led to the assumption that rock glaciers in the two study areas are inherited permafrost features rather than climatic permafrost features. Finally, the different and successful methods used in this chapter – slopebased units statistical differentiation, GIS modeling – deserve further developments, coupling and implementations related to the same subject or to others.

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REFERENCES Asahi, K.,1999. Distribution and its inventory of active rock glaciers in Kanchenjunga Himal. In: Watanabe, T. (Ed), Kanchenjunga 1998 Reports, Sapporo, 67-70. Asahi, K., Watanabe, T., 2004. Paleoclimate of the Nepal Himalayas during the Last Glacial: reconstructing from glacial equilibrium-line altitudes. Himalayan Journal of Sciences, 2, 100-101. Baidya, S.K., 2007. Climate research in the Nepal Himalaya. Developments in Earth Surface Processes, 10, 291-299. Baroni, C., Carton, A., Roberto, A., Seppi, R.., 2004. Distribution and behaviour of rock glaciers in the Adamello-Presanella Massif (Italian Alps). Permafrost and Periglacial Processes, 15, 243-259. Barsch, D., 1987. The problem of the ice-cored rock glacier. In: Giardino, J.R., Shroder, J.F., Vitek, J.D. (Ed), Rock glaciers, Allen & Unwin, London, 45-53. Barsch, D., 1996. Rockglaciers. Indicators for the present and former geoecology in high mountain environments. Springer, Berlin, 319 p. Barsch, D., Jakob, M., 1998. Mass transport by active rock glaciers in the Khumbu Himalaya. Geomorphology, 26, 215-222. Béguin, H., 1979. Méthodes d’analyse géographique quantitative. Litec, Paris, 252 p. Brenning, A., Trombotto, D., 2006. Logistic regression modeling of rock glacier and glacier distribution: topographic and climatic controls in the semi-arid Andes. Geomorphology, 81, 141-154. Capps, S.R., Jr., 1910. Rock glaciers in Alaska. Journal of Geology, 18, 359-375. Chueca, J., 1992. A statistical analysis of the spatial distribution of rock glaciers, Spanish Central Pyrenees. Permafrost and Periglacial Processes, 3, 261-265. Clark, H.C., Steig, E.J., Potter, N., Jr., Gillespie, A.R., 1998. Genetic variability of rock glaciers. Geografiska Annaler, 80A, 175-182. Debelmas, J., Desmons, J. (Ed), 1997. Géologie de la Vanoise. Documents du BRGM 266, Éditions BRGM, Orléans, 187 p. Delaloye, R., Strozzi, T., Lambiel, C., Perruchoud, E., Raetzo, H., 2008. Landslide-like development of rock glaciers detected with ERS-1/2 SAR interferometry. Proceedings of PRINGE 2007 Workshop, Frascati, Italy, 26-30 November 2007. Devkota, B.D., Omura, H., Kubota, T., Morita, K., 2006. State of vegetation, erosion climatic conditions and re-vegetation technology in mid hill area of Nepal. Journal of the Faculty of Agriculture, Kyushu University, 51, 362-365. Douguédroit, A., de Saintignon, M.F., 1970. Méthode d’étude de la décroissance des températures en montagne de latitude moyenne: exemple des Alpes françaises du Sud. Revue de Géographie alpine, LVIII, 453-472. Dramis, F., Govi, M., Guglielmin M., Mortara, G., 1995. Mountain permafrost and slope instability in the Italian Alps: the Val Pola Landslide. Permafrost and Periglacial Processes, 6, 73-82. Fort, M., 2003. Are high altitudes, lava stream-like, debris mixtures all rock glaciers? A perspective from the Western Himalaya. Zeitschrift für Geomorphologie, 48, 11-29.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

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Fukui, K., Fujii, Y., Ageta, Y., Asahi K., 2007. Changes in the lower limit of mountain permafrost between 1973 and 2004 in the Khumbu Himal, the Nepal Himalayas. Global and Planetary Change, 252-256. Guglielmin, M., Smiraglia, C., 1998. The rock glacier inventory of the Italian Alps. Proceedings of the 7th International Permafrost Conference, 373-382. Haeberli, W., Vonder Mühll, D., 1996. On the characteristics and possible origin of ice in rock glacier permafrost. Zeitschrift für Geomorphologie, Suppl.-Bd. 104, 43-57. Haeberli, W., Hallet, B., Arenson, L., Elcolin, R., Humlun, O., Kääb, A., Kaufmann, V., Ladanyi, B., Matsuoka, N., Springman, S., Vonder Mühll, D., 2006. Permafrost creep and rock glacier dynamics. Permafrost and Periglacial Processes, 17, 189-214. Harris, C., Davies, M.C. R., Etzelmüller, B., 2001. The assessment of potential geotechnical hazards associated with mountain permafrost in a warming global climate. Permafrost and Periglacial Processes, 12, 145–156. Hassinger, J.M., Mayenski, P.A., 1983. Morphology and dynamics of the rock glaciers in Southern Victoria Land, Antarctica. Arctic and Alpine Research, 15, 351-368. Humlum, O., 2000. The geomorphic significance of rock glaciers: estimates of rock glacier debris volumes and headwall recession rates in West Greenland. Geomorphology, 35, 4167. Ichiyanagi, K., Yamanaka, M.D., Muraji, Y., Vaidya, B.K., 2007. Precipitation in Nepal between 1987 and 1996. International Journal of Climatology, 27, 1753-1762. Iwata, S., Aoki, T., Kadota, T., Seko, K., Yamaguchi, S., 2000. Morphological evolution of the debris cover on Khumbu Glacier, Nepal, between 1978 and 1995. In : Nakawo, M., Raymond, C.F., Fountain, A. (Ed), Debris-covered glaciers, IAHS Publication 264, Wallingford, 3-11. Jakob, M., 1992. Active rock glaciers and the lower limit of discontinuous alpine permafrost in the Khumbu Himalaya, Nepal. Permafrost and Periglacial Processes, 3, 253-256. Johnson, B.G., Thackray, G.D., Van Kirk, R., 2007. The effect of topography, latitude, and lithology on rock glacier distribution in the Lemhi Range, central Idaho, USA. Geomorphology, 91, 38-50. Kääb, A., Frauenfelder, R., Roer, I., 2007. On the response of rock glacier creep to surface temperature increase. Global and Planetary Change, 56, 172-187. Kaiser, B., 1975. Étude géodynamique dans le massif de la Vanoise : orientations et résultats récents. Travaux scientifiques du Parc national de la Vanoise, VI, 9-40. Kaiser, B., 1983. Morphodynamique périglaciaire en Vanoise. Observations et mesures sur deux formes : talus d’éboulis et glacier-rocheux. Travaux scientifiques du Parc national de la Vanoise, XIII, 55-80. Kaiser, B., 1987. Les versants de Vanoise : enjeux traditionnels et fonctionnement morphoclimatique. PhD Thesis, Paris 7 University, 1088 p. Monnier, S., 2006. Les glaciers rocheux, objets géographiques. Analyse spatiale multiscalaire et investigations environnementales. Application aux Alpes de Vanoise. PhD Thesis, Paris 12-Val de Marne University, 339 p. Monnier, S., Camerlynck, C., Rejiba, F., 2008. Ground Penetrating Radar survey and stratigraphic interpretation of the Plan du Lac rock glaciers, Vanoise Massif, Northern French Alps. Permafrost and Periglacial Processes, 19, 19-30.

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Morel, S., Baron, E., Claudin, J., Miellet, P. (Ed), 1998. Atlas du Parc national de la Vanoise. Parc national de la Vanoise, collection Atlas des Parcs nationaux de France (coord. GIP ATEN, TED ALITEC), Chambéry, 64 p. Onde, H., 1938. La Maurienne et la Tarentaise. Étude de géographie physique. Arthaud, Grenoble, 623 p. Potter, N., Jr., 1972. Ice-cored rock glacier, Galena Creek, Northern Absaroka Mountains, Wyoming. Geological Society of America Bulletin, 83, 3025-3058. Potter, N., Jr., Steig, E.J., Clark, D.H., Speece, M.A., Clark, G.M., Updike, A.U., 1998. Galena Creek rock glacier revisited – new observations on an old controversy. Geografiska Annaler, 80A, 251-265. Regmi, D., 2006. A geomorphic study of permafrost in the Nepal Himalaya. PhD Thesis, Hokkaido University. Upreti, B.N., Le Fort, P., 1999. Lesser Himalayan crystalline nappes of Nepal: problems of their origin. In: Macfarlane, A., Sorkhabi, R.B., Quade, J. (Ed), Himalaya and Tibet: mountain roots to mountain tops, Geological Society of America Paper 328, Boulder, 225-238. Vivian, R., 1975. Les glaciers des Alpes occidentales, étude géographique: l’emprise de la glaciation actuelle et ses fluctuations récentes, le rôle des eaux, l’aménagement du paysage montagnard par les glaciers. PhD Thesis, Grenoble I University, 513 p. Voiron, H., 1983. Les régimes nivométriques de la Vanoise. Travaux scientifiques du Parc national de la Vanoise, XIII, 81-89. Wahrhaftig, C., Cox, A., 1959. Rock glaciers in the Alaska Range. Bulletin of the Geological Society of America, 70, 383-436. Washburn, A.L., 1979. Geocryology : a survey of periglacial processes and environments. Edward Arnold, London, 406 p. Whalley, W.B., Martin, H.E., 1992. Rock glaciers: II. Models and mechanisms. Progress in Physical Geography, 16, 127-186. White, P.G., 1979. Rock glacier morphometry, San Juan Mountains, Colorado : summary. Geological Society of America Bulletin, 90, 515-518.

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In: Geomorphology and Plate Tectonics Editors: D. M. Ferrari, A. R. Guiseppi

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Chapter 4

ON SHAKY GROUND: ARCTIC COMMUNITIES IN UNEASY TRANSITION TO A NEW CLIMATIC ORDER Mary J. Thornbush1,* and Oleg Golubchikov2 1

2

Lakehead University, Orillia Campus, Orillia, Ontario, Canada University of Oxford, School of Geography and the Environment, Oxford, England, UK

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ABSTRACT Much attention has recently been given to the Arctic within a context of climate change. Its high latitude has made the Arctic one of the most sensitive regions on Earth, conveying landscape modifications in a warming world. This chapter examines the evidence of landscape change from a combined geomorphologic and socio-political approach by considering permafrost and thermokarst development, issues around the opening of the region (i.e. the Northwest Passage in Canada), as well as varied implications on local communities, international affairs, and geopolitics. The consideration of these issues is based on the assumption that climatic warming is changing the Arctic landscape and that northern regions will be a focal point in the search for resources.

Keywords: climate change; northern regions; permafrost; geopolitics; resource exploration; energy

INTRODUCTION An integrated approach is necessary when addressing landscape change in the Arctic because of the far-reaching implications of the issue. In such a harsh climate, humans have a close-linked relationship with their environment so that physical issues affect adaptation and society. The main purpose of this chapter is to take a holistic (physical-human) geographical approach to landscape change in the Arctic, bordering Alaska (USA), Canada, Greenland *

Corresponding author: Tel: +01 705-330-4071; Fax: +01 705-329-4648, Email: [email protected]

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(Denmark), Norway, and Russia. In this way, observed physical change is examined and connected to how it is affecting Arctic communities. The objectives are: 1) to discuss landscape change in the context of the recent warming, 2) to examine associated sociocultural change, and 3) to present challenges and opportunities within the context of melting ice in the Arctic Ocean.

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OBSERVATIONS AND PREDICTIONS OF LANDSCAPE CHANGES There are currently various debates relating to climate change. Most scientists (even the skeptics) acknowledge that climatic warming is occurring; however, some believe that the issue is being exaggerated and is not fully supported by existing datasets (i.e. [1]). Certainly, climate change is not a new phenomenon, since climate has oscillated throughout Earth’s history [2-3]. There are also other linked issues involved; air pollution (gaseous emissions), for example, has been implicated in the debate since the beginning (i.e. [4]). However, what is important for scientists is to consider the evidence and make suggestions for adaptation and policy. Vast observations have been made about the changing climate of the Arctic. It is thought that climatic changes will be greater in polar regions, such as the Arctic, than elsewhere on Earth (i.e. [5]), and these changes are said to have already started [6]. One of the most noticeable changes associated with the recent warming is the advancement of spring. Researchers have documented “extremely rapid climate-induced advancement of flowering, emergence and egg-laying in a wide array of species in a high-arctic ecosystem,” with much of phenological shifting associated with the timing of snowmelt (advanced on average by 14.6 days between 1996 and 2005) [7]. The spatial distribution of snow is also important in the Arctic, since it controls soil temperatures as well as vegetation types and the quality of soil organic matter [8]. Researchers have used general circulation models (GCMs) to forecast change and have predicted a 20-30% increase in the thickness of the active layer, with the greatest increase towards the northernmost part of the land part of the region [9]. Natural change in the Arctic is not new and the last interglaciation could reveal much about what can be expected in the future of the recent warming. During the last interglacial period (some 130,000 years ago), the average summer insolation increased by 13% in the Arctic (compared with 11% across the Northern Hemisphere) with summer temperature anomalies 4-5°C above present, which reduced sea ice in the Arctic Ocean, also reduced permafrost, and led to the northward expansion of the boreal forest [10]. GCMs assuming a greater temperature and precipitation in the last interglaciation have conveyed reduced sea-ice (extent and thickness) with winters 2-8°C warmer than at present and the northward displacement of tundra and taiga biomes [11]. General observations of the last interglacial period have indicated a higher (mean) summer temperature (maximum of 9-14.5°C), a longer growing season, and drier soils (in areas outside thermokarst depressions) [12]. Temperature logs from 61 wells have shown a warming of the ground surface between 60° and 82°N in northern Canada, which started in the late-18th century and lasted until the 20th century and has exceeded climate proxies by about 2°C [13]. An implication for areas of ice-rich permafrost during the last glacial-interglacial transition was the development of thermokarst

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sediments (and sedimentary structures) in the Tuktoyaktuk Coastlands, for example, of the western Arctic (Canada) [14]. Most predictions of future landscape change are temperature-dependent. For example, a warming of 2°C in the Arctic could lead to a 30% increase in sediment flux, which is also affected by river discharge into the Arctic Ocean (i.e. increments of 20% in water discharge could increase sediment load by 10%) [15]. It is anticipated that a warming of 5°C could remove Arctic pack ice in summer [16]. Less sea ice (extent and duration) along with a warming permafrost (with a thicker active layer and the development of thermokarst), rising sea levels, and increasing storm activity could all contribute to increased rates of coastal erosion in Arctic regions (i.e. thaw slumps increased between 1952 and 2000 in the Yukon Territory, Canada along the southern Beaufort Sea) [17]. Temperature should not be considered in isolation and (effective) moisture should be considered, particularly where landscape-scale change is concerned [18]. Moreover, studies have indicated that natural processes alone (i.e. permafrost distribution) may operate at a slower temporal scale than when there is the addition of human activities (i.e. downstream aggradation of mining activity) [19]. It has been noted that the Arctic is changing rapidly both environmentally and socially [20], and so both should be investigated as part of an integrated system. A changing climate in the Arctic influences geomorphologic processes. Warming affects permafrost continuity in the soil column. Permafrost thawing has been reported in Alaska since 1977 near Healy (at a rate of 10 cm/yr since the late 1980s) and at Gulkana (at a rate as high as 9 cm/yr after 2000) [21]. There are implications for the biogeochemistry of the region; for example, methane hydrates, containing methane close to the Earth’s surface, though a potential source of natural gas, could have a positive feedback on climatic warming once released from melting (or thawing) permafrost [22]. The record of permafrost warming, thawing, and melting is limited and more research is needed to monitor change in the higher latitudes and to contribute towards a longer time-series of records than is currently available [23]. Drainage of melting permafrost will be of issue in the recent warming. In the Arctic Coastal Plain of northern Alaska, for example, thaw lakes are the dominant landscape process (comprising about 75% of the modern surface in the Barrow Peninsula) [24]. The hydrological response also affects wetlands in the region, which require a reliable water supply in the thaw season [25]. Besides permafrost, the mass balance of glaciers should be considered in a warming climate. Most glaciers in the Arctic (i.e. due to a higher summer temperature in northern Alaska) over past decades have generally conveyed a negative net surface mass balance and are contributing 0.13 mm/yr (outside Greenland) to global sea-level rise [26]. It has been estimated that 50% of the global average sea-level rise may be due to melting mountain and Antarctic glaciers [27]. In terms of biomes and agriculture, there are various apparent or suspected changes. The productivity of boreal fish species in the North Sea are likely to decline (with a climatic preference for warm-water species) and optimal conditions for fish farming will be displaced (northwards from northern West Norway) towards the Helgeland coast [28]. Similarly, the terrestrial system will expand and forests, for example, will have a new northward habitat limited by temperature and precipitation, fire, pests and pathogens, competition, and nonclimatic stresses (i.e. acid rain and tropospheric ozone) [29]. Angiosperms and conifers are expected to have different physiological responses to increased temperature, humidity, and

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greenhouse gases (as was evident during the Paleocene-Eocene thermal maximum) [30]. It is also expected that (at high latitudes) trees will appear in a greater abundance than grass [31]. Lichen types preferring warm conditions (i.e. wide-tropical lichens) will also proliferate [32]. Organisms with a (rapid) short-range (decadal) response to warming include insects, mollusks, and water plants [33]. The development of thermokarst (associated with permafrost warming, thawing, and melting) will likely trigger instability of human-made structures (i.e. buildings and pipelines) even if raised (i.e. utilidors) depending on the thickness of the (seasonal) active layer. Topographic changes could also lead to bending and breaking of pipelines, creating environmental contamination and resource loss. The drainage of the area is also likely to affect habitable areas in the Arctic and the location of human structures. Poleward shifting of resources (i.e. trees, which can take centuries to millennia to respond [33]) creates an opportunity for humanity, including the future possibility of agriculture incipient with increasing drainage of the area and the accumulation of organic matter and pedogenesis in a warmer environment. There will be a north-displacement of the range of some species of flora and fauna (i.e. for seals and bears) and this could mean that they may not become extinct though forced northwards into colder regions.

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SOCIO-CULTURAL AND ECONOMIC CHANGES Studies in geography, environmental sciences, anthropology, and political studies (among others) agree that inasmuch as environmental changes due to climate change will be especially pronounced in the Arctic compared to other regions, so will be attendant social changes. Climate change should not be, of course, considered as a singular factor affecting the life of Arctic communities, for technological, political, and economic regimes may be much more overwhelming and more rapid in their impacts (i.e. [34-35]).† What is unique about the impact of climate change, however, is that it emerges not through societal channels, but from nature and so disregards political borders and other social regimes whilst still remaining embedded in local environmental conditions. Irrespective of its relative role, climate change will expose human activities in the Arctic to the challenges of serious shocks and reconfigurations. In terms of socio-economic, demographic, and cultural changes in a new climatic order, there is a general consensus of asymmetry between the implications, on the one hand, for indigenous communities relying on subsistence livelihoods and, on the other, for capitalist activities hungry for the mineral and energy wealth of the Arctic. While the former are believed to be disadvantaged by environmental destabilization and could suffer from further displacement and alienation, the latter are assumed, at large, to benefit from a warmer Arctic. Traditionally, the Arctic has been home to a diversity of indigenous cultures that harvest their subsistence from natural ecosystems. The links between landscape, on the one hand, and language, culture, and tradition, on the other, are therefore much prominent here. Any change in natural ecosystems destabilizes these links. Indeed, studies that compare indigenous voices with scientific evidence of a changing climate already report repercussions on the spatiotemporal regime of indigenous communities in the last few decades [35]. In Northern Alaska

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and Canada, for example, warmer winters and a greater volatility in weather mean shorter periods of frozen ground and sea and river ice. However, these conditions are important for local hunters and fishers in order to gain access to the areas of their traditional activities, such as marine and land animal hunting and river and lake fishing through ice (i.e. [36]). In Alaska, the number of days during which temperatures were cold enough to allow ice roads to be used fell from 200 to 100 per year since 1970 [35]. Furthermore, the patterns of distribution and availability of wildlife and fish species also change, while non-Arctic species and diseases become more widespread. Reindeer herding in Northern Europe and Russia is particularly vulnerable to new diseases and insects. Local residents need to develop new strategies in hunting, fishing, gathering, and herding and change their habits and lifestyle, and even re-settle, but this situation is not without stress. More generally, increases in environmental variability affect people’s ability to plan. More uncertainty and economic hardship due to reduced access and poorer harvests make people accept a greater risk during their work, with more accidents as a result. Increased uncertainty and variability of environmental conditions, coupled with overall changing landscapes, also undermine the traditional system of knowledge and leave indigenous peoples with a feeling of being alienated by their own land [35, 37-38]. On the other hand, climate change increases the pressures of globalization. As the Arctic gets warmer, areas rich in mineral and fuel resources become more and more attractive for extractive industries and for activities typical for more southern areas. This will certainly lead to a greater integration of “the northern peripheries” into the spaces of global capital. But the vulnerable natural ecosystems of the Arctic – and, consequently, native social systems – become exposed to a double pressure, both from climate change and from positive economic feedback to it. It is especially since the 20th century that traditions and cultures of indigenous peoples have been yielding to “modernization.” Apart from Canada and Greenland, indigenous peoples in Arctic regions are already minorities in their land [37]. Disintegration of traditional ways of life and migration to cities has been followed by the loss of culture, identity, and traditions. This loss, which is regrettable as it is, may also be damaging to public and societal health. Although “modernization” in the past might be associated with a better state of health and extended life expectancy for Arctic peoples, health conditions are now less elastic to increased levels of industrial development. It is rather negative implications that now become more prominent, including increased levels of abuse, violence, and social isolation. For example, Inuit communities in Greenland and Canada demonstrate the world’s highest suicide rate – as much as 10% of all deaths among the Inuit are believed to be from suicide, although the rate was very low in the 1970s [39-40]. The other side of the coin is, of course, greater economic development. In addition to extractive industries on land and offshore, new economic activities in the Arctic may also be linked to increased access for marine and river transport and fishing, increased opportunities for hydroelectric development, and improved conditions for agriculture [41]. In the longerterm, when drainage has settled, the land will gradually become more fertile (organic-rich) and farmable. Greenland’s agriculture is already benefiting from an expanded growing season, flourishing crops, and cattle on a land that was only recently covered with glaciers [42]. There should also be vast opportunities for the forestry industry, especially of deciduous hardwood species, in the future (at least in some parts of the Arctic that are not covered by †

Consider, as one example, the recent rapid post-socialist transition in Russia.

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bogs). These are all important dimensions, indicating that seen as an economic and sociocultural entity the new Arctic will appear to future generations as quite a different place than what it is now. At the same time, it is also evident that “modern” economic activities and urban places that already exist in polar and sub-polar regions are facing serous challenges of melting permafrost and other complications that damage constructions. This is particularly a largescale challenge for Russia – simply for the reason that this nation contains about half of the world’s Arctic population, mostly residing in large cities [37]. Particularly, Siberian cities and villages built on permafrost will face a state of emergency within a short time. But transport infrastructure is also vulnerable. In the oil producing Khanty-Mansi autonomous region of western Siberia, for example, as many as 1,720 pipeline accidents were reported in a single year, contaminating an area of 640 km2 [35]. It is most likely that such accidents will only increase in frequency and intensity unless pre-emptive measures are taken. Tackling challenges of a new geothermal terrain regime requires either an expensive remedial technoengineering investment or surrender from certain places. While the former strategy will rely on an influx of new labor, the latter will lead to a re-location of activities within the Arctic rather than their total abandonment. Either way will, in fact, bring further changes to the overall socio-cultural and demographic character of the region. Another important socio-cultural implication of climate change in the Arctic is the very policy responses to climate change. It is apparent that social practice is very much framed by policies, regulations, and other formal institutions, so that new policy regimes, like the present ones, will inevitably play a fundamental part in the formation of the new sociocultural landscape of the Arctic. Even those who are still skeptical about climate change can hardly deny that the dominant discourses on climate conditions do bring fundamental change to life. Climate change needs to be understood not purely as a physical phenomenon, but also as a cultural object – for the perceptions about global climate are formed and informed by the complex interaction of scientific knowledge, public discourse, everyday observations, and social behavioral patterns. In this sense, climate change is a socially-constructed agenda [4344] that forms specific policy responses. In the next section, are highlighted, for example, implications for energy and security policies and geopolitics. Other polices that will affect human activities in the Arctic include adaptation policies. In short, climate change – or rather social interpretations and speculations of climate change – bring an array of policy responses that start playing their own role in making the Arctic – not only by mitigating, preventing, or augmenting ongoing socio-economic processes, but also by triggering entirely new changes.

CHALLENGES AND OPPORTUNITIES ARISING FROM THE MELTING ARCTIC OCEAN Over the next few decades, the circumpolar Arctic will experience challenges associated with ocean warming, the melting of glaciers, and sea-level rise, leading to an overall net rise in the region. Some models anticipate that by as early as the mid-2010s, the Arctic may be free of ice in the summer. During 2008, the summer minimum ice extent, albeit slightly above the record minimum in 2007 (4.7 vs. 4.3 million km2), reinforces the strong negative trend observed over the past 30 years. At the record minimum in 2007, the extent of the sea ice

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cover was 39% below the long-term average from 1979 to 2000 (i.e. [45-46]). The melting Arctic ice alone raises a number of issues at varied spatial scales – from emergency of a local scale to intensified actions over Arctic geopolitics at the international scale. At the local level, a reduction in sea-ice in the Arctic Ocean results in storms, which creates more flooding in low-lying areas – for example, in the Mackenzie Delta [47]. This establishes concerns over access to the area in the outer Mackenzie Delta and Beaufort shelf in terms of development and resource extraction (i.e. oil and gas platforms). Coastal communities in the western American Arctic are already experiencing the gradual erosion of their coastlines due to storm-driven waves that are no longer being buffered by sea-ice; this is destroying their buildings and heritage [48]. Because of these changes, communities in Alaska and the Northwest Territories in Canada may have to be relocated. The Alaska government, for example, has already considered relocating the Eskimo village of Shishmaref (on a small island on the edge of the Arctic Circle) and four other coastal communities (Kivalina, Koyukuk, and Newtok in Alaska and Tuktoyaktuk, Canada) may have to be evacuated in the next 50 years [49]. At the regional level, ocean resources will open-up, as around the Arctic Ocean, with easier access on-water and due to fish migrations northward into the region. More generally, navigation routes will improve. There is the possibility for shipping through the Northwest Passage over North America [50]. Russia’s Northern Sea Route (also known as Northeast Passage), which is a system of sea lanes of 5,000 km over Eurasia, will become economically more feasible to operate. When the ice recedes enough, it will also be possible to navigate directly over the Northern Pole – i.e. between the Arctic countries, but also from the Atlantic and Pacific Oceans. These routes will considerably reduce present shipment distances. No less important are challenges and opportunities at an international scale. The Arctic Ocean is where issues of national interests, energy resources, and climate change closely converge. During the Cold War era, the Arctic was a major arena for geopolitical observations and contestations (i.e. [51]). Now, climate warming is sharpening geopolitical differences once again, with some geopolitically-based strife amongst the member states of the Arctic, including primarily Denmark, Russia, the US, Canada, and Norway, but also the EU, Iceland, and other stakeholders. Territorial disputes have already been kindled between Canada and the US over whether the Northwest Passage is a Canadian or international water. The opening of the Northwest Passage in the Canadian Arctic is causing some anxiety around national security for the Coastal Guard and Canadian military, which has established a “sovereignty patrol” [52]. Canada is also disputing with Denmark over Hans Island, which is located between Canada and Greenland. Recent estimates predict an enormous portion of global oil and gas reserves to be hidden under the Arctic Ocean. Given that this wealth will become more accessible in the future, Arctic nations are already seen to be involved in a kind of “Petro-rush.” The UN Convention on the Law of the Sea stipulates that coastal states can claim territory of 200 nautical miles from their shoreline and exploit the natural resources within that zone. Nations can extend that limit to up to 350 nautical miles from their coast if they prove that the undersea continental plate is a natural extension of their territory. Russia made the single largest claim to the sector of the Arctic Ocean adjacent to its territory and up to the Northern Pole (originally submitted to the UN in 2001). This claim is so far opposed by other states, since most of them are making their own overlapping claims, but it is based on the argument that the Lomonosov Ridge is an extension of Russia’s shelf. In this light, the planting of a

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titanium Russian flag on the floor of the Arctic Ocean at the Northern Pole in 2007 [53] was interpreted less as a technological feat, but rather as a symbolic event, which irritated other “stakeholders.” All such developments indicate a beginning of the era of “climate geopolitics” in the Arctic, which has the potential to threaten international peace. Thus, another dimension of increased “globalization” in the Arctic may be its re-militarization. Although the end of the Cold War was followed by certain efforts to decrease a military presence in the Arctic (including bans on nuclear tests), recent years have shown an opposite trend, with an intensifying military presence in regions such as the Barents Sea and northern Norway. Alaska has also become a key site for deployment of the US National Missile Defence system, as the US withdrew from the US/USSR Anti-Ballistic Missile Treaty of 1972 in 2001. The expectations of the Arctic meltdown coupled with the forecasts for the Arctic Ocean’s resource wealth only intensify the hawkish national security discourses that demand additional warships, submarines, military aircrafts, and land guards in the area. On the other hand, it is also a test to the abilities of the generally wealthy Arctic nations to cooperate and find satisfactory compromises. There is already a rather “thick” layer of international institutions for the Arctic, including non-state actors, which may serve to improve cooperation [37, 54]. However, new international regimes will also be required if national ambitions are to be mediated in the new complex reality [55]. It is, thus, clear that Arctic geopolitics will too be undergoing a significant and uneasy transition induced by both scientific observations about climate change and surrounding political discourses.

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CONCLUSION The primary changes that are occurring in the Arctic due to a warming climate are physical in nature, and their ramifications (secondary changes) are social and cultural in nature. It is crucial to understand the physical changes and the socio-cultural response of the holistic system. Various nature-human interactions are evident in this region, which will be stressed with global change. The largest foreseeable changes will be associated with warming, thawing, and melting in the region. As temperatures rise, more and earlier thawing is evident, which will inevitably result in melting of ice across the Arctic. The ramifications are for access (i.e. opening of the Arctic waters) and shipping as well as storm and flood activity, affecting development and land stability (at least in the short-term). Where there are costs, however, there are also benefits to Arctic warming, such as easier access and exploration as well as expansion into the region (of wildlife as well as people). For this latter reason, in particular, human concerns will become increasingly relevant in the Arctic.

REFERENCES [1] [2]

Lomborg, B. Cool It: The Skeptical Environmentalist’s Guide to Global Warming; Alfred A. Knopf: New York, 2007, 253 pp. Michaels, P. J. Meltdown: The Predictable Distortion of Global Warming by Scientists, Politicians, and the Media; Cato Institute: Washington, 2004, 271 pp.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Climate Change in the Arctic [3] [4] [5]

[6] [7] [8] [9]

[10] [11]

[12]

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[13]

[14] [15] [16]

[17]

[18]

[19]

[20]

93

Singer, S. F.; Avery, D. T. Unstoppable Global Warming: Every 1,500 Years; updated and expanded edition; Rowman & Littlefield Publishers, Inc.: Toronto, 2007, 278 pp. Weller, G. “Global pollution and its effect on the climate of the Arctic,” Sci. Total Environ. 1995, 160/161, 19-24. Kane, D. L.; Hinzman, L. D.; Zarling, J. P. “Thermal response of the active layer to climatic warming in a permafrost environment,” Cold Reg. Sci. Technol. 1991, 19, 111122. Demek, J. “Global warming and permafrost in Eurasia: a catastrophic scenario,” Geomorphology 1994, 10, 317-329. Høye, T. T.; Post, E.; Meltofte, H.; Schmidt, N. M.; Forchhammer, M. C. “Rapid advancement of the High Arctic,” Curr. Biol. 2007, 17, R449-R451. Elberling, B. “Annual soil CO2 effluxes in the High Arctic: the role of snow thickness and vegetation type,” Soil Biol. Biochem. 2007, 39, 646-654. Anisimov, O. A.; Shiklomanov, N. I.; Nelson, F. E. “Global warming and active-layer thickness: results from transient general circulation models,” Global Planet. Change 1997, 15, 61-77. CAPE-Last Interglacial Project Members “Last Interglacial Arctic warmth confirms polar amplification of climate change,” Quaternary Sci. Rev. 2006, 25, 1383-1400. Harrison, S. P.; Kutzbach, J. E., Prentice, I. C.; Behling, P. J.; Sykes, M. T. “The response of Northern Hemisphere extratropical climate and vegetation to orbitally induced changes in insolation during the last interglaciation,” Quaternary Res. 1995, 43, 174-184. Kienast, F.; Tarasov, P.; Schirrmeister, L.; Grosse, G.; Andreev, A. A. “Continental climate in the East Siberian Arctic during the last interglacial: implications from palaeobotanical records,” Global Planet. Change 2008, 60, 535-562. Majorowicz, J. A.; Skinner, W. R.; Šafanda, J. “Large ground warming in the Canadian Arctic inferred from inversions of temperature logs,” Earth Planet. Sc. Lett. 2004, 221, 15-25. Murton, J. B. “Thermokarst sediments and sedimentary structures, Tuktoyaktuk Coastlands, western Arctic Canada,” Global Planet. Change 2001, 28, 175-192. Gordeev, V. V. “Fluvial sediment flux to the Arctic Ocean,” Geomorphology 2006, 80, 94-104. Hollin, J. T.; Barry, R. G. “Empirical and theoretical evidence concerning the response of the Earth’s ice and snow cover to a global temperature increase,” Environ. Int. 1979, 2, 437-444. Lantuit, H.; Pollard, W. H. “Fifty years of coastal erosion and retrogressive thaw slump activity on Herschel Island, southern Beaufort Sea, Yukon Territory, Canada,” Geomorphology 2008, 95, 84-102. Mann, D. H.; Peteet, D. M.; Reanier, R. E.; Kunz, M. L. “Responses of an arctic landscape to Lateglacial and early Holocene climatic changes: the importance of moisture,” Quaternary Sci. Rev. 2002, 21, 997-1021. Alessa, L.; Kliskey, A.; Busey, R.; Hinzman, L.; White, D. “Freshwater vulnerabilities and resilience on the Seward Peninsula: integrating multiple dimensions of landscape change,” Global Environ. Change 2008, 18, 256-270. Holland, G. “The Arctic Ocean – the management of change in the northern seas,” Ocean Coast. Manage. 2002, 45, 841-851.

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[21] Osterkamp, T. E. “The recent warming of permafrost in Alaska,” Global Planet. Change 2005, 49, 187-202. [22] Kvenvolden, K. A. “Methane hydrate – a major reservoir of carbon in the shallow geosphere?” Chem. Geol. 1988, 71, 41-51. [23] Kimball, J. S.; McDonald, K. C.; Keyser, A. R.; Frolking, S.; Running, S. W. “Application of the NASA Scatterometer (NSCAT) for determining the daily frozen and nonfrozen landscape of Alaska,” Remote Sens. Environ. 2001, 75, 113-126. [24] Eisner, W. R.; Bockheim, J. G.; Hinkel, K. M.; Brown, T. A.; Nelson, F. E.; Peterson, K. M.; Jones, B. M. “Paleoenvironmental analyses of an organic deposit from an erosional landscape remnant, Arctic Coastal Plain of Alaska,” Palaeogeogr. Palaeocl. 2005, 217, 187-204. [25] Woo, M.-K.; Young, K. L. “High Arctic wetlands: their occurrence, hydrological characteristics and sustainability,” J. Hydrol. 2006, 320, 432-450. [26] Dowdeswell, J. A.; Hagen, J. O.; Björnsson, H.; Glazovsky, A. F.; Harrison, W. D.; Holmlund, P.; Jania, J.; Koerner, R. M.; Lefauconnier, B.; Ommanney, C. S. L.; Thomas, R. H. “The mass balance of circum-Arctic glaciers and recent climate change,” Quaternary Res. 1997, 48, 1-14. [27] Lambeck, K. “Late Pleistocene, Holocene and present sea-levels: constraints on future change,” Palaeogeogr. Palaeocl. (Global Planet. Change section) 1990, 89, 205-217. [28] Stenevik, E. K.; Sundby, S. “Impacts of climate change on commercial fish stocks in Norwegian waters,” Mar. Policy 2007, 31, 19-31. [29] Peters, R. L. “Effects of global warming on forests,” Forest Ecol. Manage. 1990, 35, 13-33. [30] Schouten, S.; Woltering, M.; Rijpstra, W. I. C.; Sluijs, A.; Brinkhuis, H.; Sinninghe, J. S.; Damsté, J. S. S. “The Paleocene-Eocene carbon isotope excursion in higher plant organic matter: differential fractionation of angiosperms and conifers in the Arctic,” Earth Planet. Sc. Lett. 2007, 258, 581-592. [31] Shellito, C. J.; Sloan, L. C. “Reconstructing a lost Eocene paradise: Part I. Simulating the change in global floral distribution at the initial Eocene thermal maximum,” Global Planet. Change 2006, 50, 1-17. [32] Van Herk, C. M.; Aptroot, A.; Van Dobben, H. F. “Long-term monitoring in the Netherlands suggests that lichens respond to global warming,” Lichenologist 2002, 34, 141-154. [33] Velichko, A. A.; Borisova, O. K.; Zelikson, E. M.; Faure, H.; Adams, J. M.; Branchu, P.; Faure-Denard, L. “Greenhouse warming and the Eurasian biota: are there any lessons from the past?” Global Planet. Change 1993, 7, 51-67. [34] Lange, M. A. “Assessing climate change impacts in the European north,” Climatic Change 2008, 87, 7-34. [35] ACIA Arctic Climate Impact Assessment; Cambridge University Press: Cambridge, 2005, 1020 pp. [36] Riedlinger, D.; Berkes, F. “Contributions of traditional knowledge to understanding climate change in the Canadian Arctic,” Polar Record 2001, 37, 315-328. [37] AHDR Arctic Human Development Report; Stefansson Arctic Institute: Akureyri, Iceland, 2004, 242 pp. [38] Hinzman, L. D.; Bettez, N. D.; Bolton, W. R.; Chapin, F. S.; Dyurgerov, M. B.; Fastie, C. L.; Griffith, B.; Hollister, R. D.; et al. “Evidence and implications of recent climate

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Climate Change in the Arctic

[39] [40] [41]

[42] [43] [44] [45] [46]

Copyright © 2009. Nova Science Publishers, Incorporated. All rights reserved.

[47] [48] [49] [50] [51] [52] [53] [54] [55]

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change in Northern Alaska and other Arctic regions,” Climatic Change 2005, 72, 251298. Bjerregaard, P.; Lynge, I. “Suicide - a challenge in modern Greenland,” Arch. Suicide Res. 2006, 10, 209-220. Pedersen, H. S. “Health in the Arctic and climate change,” Polar Research 2007, 26, 104-106. Chapin III, F. S.; Hoel, M.; Carpenter, S. R.; Lubchenco, J.; Walker, B.; Callaghan, T. V.; Folke, C.; Levin, S. A.; et al. “Building resilience and adaptation to manage Arctic change,” Ambio 2006, 35, 198-202. Traufetter, G. “Arctic harvest: global warming a boon for Greenland's farmers,” SpiegelOnline 2006, August 30, 2006. Hulme, M. “Geographical work at the boundaries of climate change,” T. I. Brit. Geogr. 2008, 35, 5-11. Pettenger, M. E. The Social Construction of Climate Change: Power, Knowledge, Norms, Discourses; Ashgate Press: Aldershot, 2007, 255 pp. Richter-Menge, J.; Comiso, J.; Meier, W.; Nghiem, S.; Perovich, D. (2008). Sea ice cover, Arctic Report Card. http://www.arctic.noaa.gov/reportcard/seaice.html. Stroeve, J.; Serreze, M.; Drobot, S.; Gearheard, S.; Holland, M.; Maslanik, J.; Meier, W.; Scambos, T. “Arctic sea ice extent plummets in 2007,” EOS T. Am. Geophys. Union 2008, 89, 13-14. “The new climate: international polar year,” Globe and Mail 2008, April 4, 2008, p. A3. Struzik, E. “Our shrinking coastlines,” Toronto Star 2007, November 24, 2007. Struzik, E. “Big thaw yields surprises,” Toronto Star 2007, November 17, 2007. Struzik, E. “The new cold war,” Toronto Star 2007, November 17, 2007. Roucek, J. S. “The geopolitics of the Arctic,” Am. J. Econ. Sociol. 1983, 42, 463-471. Shukman, D. “Vast cracks appear in Arctic ice – Canadian geographers at work,” BBC News 2008, May 23, 2008. Reynolds, P. “Trying to head off an Arctic ‘gold rush’,” BBC News 2008, May 29 2008. Heininen, L.; Nicol, H. N. “The importance of Northern dimension foreign policies in the geopolitics of the Circumpolar North,” Geopolitics 2007, 12, 133-165. Borgerson, S. G. “Arctic meltdown: the economic and security implications of global warming,” Foreign Aff. 2008, March/April, 63-77.

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In: Geomorphology and Plate Tectonics Editors: D. M. Ferrari, A. R. Guiseppi

ISBN: 978-1-60741-003-4 © 2009 Nova Science Publishers, Inc.

Chapter 5

GEOMORPHIC ADJUSTMENT, GEOGRAPHIC CONTEXT, AND DISTURBANCES Jordan A. Clayton* Department of Geosciences, Georgia State University, Atlanta, GA, U.S.A.

ABSTRACT

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The adjustment of natural landscapes relates to the interaction between the rate, magnitude, and continuity of the various agents of change, and the resistance of earth systems to alteration in the past and present. Three general categories encompass the nature of these interactions: continual (e.g. gravity-driven) adjustment, uniformitarian systems (those subjected to periodic pulses of adjustment), and disturbance-dominated systems (wherein singular events leave a lasting footprint on the landscape) (Schumm, 1988). Previous models of geomorphic change have tended to focus on uniformitarian systems using a quantitative approach (e.g. Wolman and Miller, 1960). This paper outlines some deficiencies of quantitative, uniformitarian models, and introduces a qualitative method, the “disturbance geomorphology model”, to treat landscape adjustment in the context of the continuum presented above. Several case studies of geomorphic adjustment are given as examples of the disturbance geomorphology approach. Finally, I argue that reconciliation between qualitative and quantitative models is possible when qualitative models are used as the theoretical framework within which specific, quantitative analyses can be based; while predictive capability is a product of the quantitative aspects of the study, geographic and temporal context is provided by an appropriate qualitative conceptualization of the problem, such as the disturbance geomorphology model discussed herein.

*

Correspondence to: [email protected], Department of Geosciences, Georgia State University, P.O. Box 4105, Atlanta, GA 30302, Phone: (404) 413-5791

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Jordan A. Clayton

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INTRODUCTION: THE IMPORTANCE OF GEOGRAPHIC CONTEXT Of primary importance to earth scientists is the ability to understand why changes occur in land surface features in space and time. To that end, many landscape and landform development models have been proposed, generally tending towards one of the following end-members: those that examine micro to local scale geomorphic phenomena quantitatively, or those that evaluate landscape and regional-scale change from a qualitative perspective (Pazzaglia, 2003). This paper examines the advantages and drawbacks of both quantitative and qualitative geomorphic models, and ultimately provides some thoughts regarding reconciliation between the two. This paper also presents a modification of several previous qualitative approaches towards understanding geomorphic change (e.g. Graf, 1977; Wolman and Gerson, 1978; Bull, 1979; Brunsden and Thornes, 1979; and many others) and advocates a new, dimensionless “disturbance geomorphology model”. First, attention must be given herein to some disadvantages inherent in quantitative models. The magnitude-frequency principle presented in Wolman and Miller’s (1960) landmark paper is one of many potentially suitable examples of the kind of quantitative model of landform development that will be examined in this article. I do not intend for the insightful and ground-breaking Wolman and Miller (1960) paper to serve as a straw man; rather, it is merely meant to be an example of a genre of quantitative, cause-effect models that, while useful under some circumstances, suffer from insufficient attention to geographic and temporal context (Spedding, 1997), as elaborated upon below. According to this well-known model, the product of a certain process’s frequency and magnitude determines the most effective, or dominant, landform-shaping events because the resultant curve will have a modal value. Small events happen frequently but are of too small a magnitude to perform much geomorphic change. Conversely, large magnitude events may drastically change the affected landforms, but they happen too infrequently to be of much long-term significance. The events that produce the most significant/durable landscape change are those that balance highenough frequency with moderate-high magnitudes. There is much inherent appeal in this model, and it is not surprising that it has been long embraced as a dominant paradigm in geomorphologic theory. Its success may be partly due to the relative ease of measuring initiating processes, e.g. flood peak discharge, as compared to system responses, e.g. bed load transport (Chorley, 1978; Crozier, 1999). Still, I will argue herein that, with some noteworthy exceptions (e.g. Andrews, 1980; Simon, 1992; Torizzo and Pitlick, 2004), quantitative models such as this have limited applicability in geomorphology in the absence of a geographic and temporal context. To consider the geographic framework is to incorporate both dimensionality and position. Dimensionality in this sense refers to the integration of a feature’s scale, extent, and shape. A feature’s position, or location, is its dimensionality relative to other features in space and events in time. The manifestations of landscape adjustment processes are specific to the spatial scale and geographic location considered (Gretener, 1967; 1984; Schumm and Lichty, 1965; Lane and Richards, 1997; Bauer et al., 1999; Dikau, 1999; Rhoads, 2006). To describe a landscape feature’s geographic framework, then, is to consider the influence of proximal forms and processes, regional variations in environmental factors (e.g. precipitation intensity), recent geomorphic events and other antecedent conditions, and the role of environmental feedbacks. Typical quantitative models omit many or all of these factors.

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SOME PROBLEMS WITH QUANTITATIVE MODELS THAT LACK SUFFICIENT GEOGRAPHIC CONTEXT

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The treatment of inherently geographic phenomena in the absence of sufficient dimensionality may increase the transferability of results but concurrently limits the meaningfulness of such transfers. Several difficulties that arise with quantitative models that neglect geographic parameters are: 1) Relationships between forcing processes and system behaviors may be not be constant over time (Graf, 1979; Pickett and White, 1985; Anderson and Sample, 1988; Costa and O’Connor, 1995; Crozier, 1999) or location (Simon and Darby, 1997; Chin, 2006; Fuller, 2007). For example, the effects of disturbances vary according to landscape position, meaning that the same event may elicit different responses on a hill slope versus a valley bottom, or on the outside of a meander versus an inflection point (Selby, 1974; Bergstrom, 1982; Kelsey, 1982a; 1982b; Magilligan, 1992; Miller and Ritter, 1996; Montgomery and Buffington, 1997; Benda et al., 1999; Fryirs and Brierley, 2001; Miller et al., 2001; Moody and Martin, 2001; Hoyle et al., 2008). Furthermore, quantitative models may ignore the effects of the areal extent of the disturbance (Wolman and Gerson, 1978; Matthews, 1983; Miller, 1988; Crozier, 1999). In fact, Wolman and Miller (1960, p. 58-59) point out that larger areas are more likely to experience an event of a given magnitude. 2) Frequency distributions used in quantitative models are typically statistically-derived and ignore temporal clustering of events (Scott, 1988; Crozier, 1999; Starkel, 1999) or the importance of variability (Yu and Wolman, 1987). Many quantitative models ignore the system’s antecedent conditions such as the accumulated lag time since the most recent disturbance, the proximity to thresholds for single or combined processes, and relative system sensitivity to change (Schumm, 1973; Selby, 1974; Graf, 1977; Wolman and Gerson, 1978; Brunsden and Thornes, 1979; Kelsey, 1982a; Yu and Wolman, 1987; Anderson and Sambles, 1988; Howard, 1988; Magilligan, 1992; Brunsden, 1996; Fucella and Dolan, 1996; Montgomery and Buffington, 1997; House and Hirschboeck, 1997; Goudie and Viles, 1999; Cannon, 2001; Emmett and Wolman, 2001; Showstack, 2002). Often the arrangement, or clustering, of conditions is more important than the magnitude of inputs (Lehre, 1982; Graf, 1988; Simon, 1992; Scoffin, 1993; Richards, 1999; Ibsen and Bromhead, 1999). In some environments landforms may assume preferentially stable forms which would thereafter be more difficult to modify (Scheidegger, 1987). The recovery of different system elements may also occur at different rates (Wolman, 1988) and all elements of system recovery may occur over timespans dissimilar to the frequency of the formative event(s) (Brunsden and Thornes, 1979). 3) Earth surface change is often initiated by not one, but a combination of factors- each with their own scales and frequency relations (Schumm and Lichty, 1965; Gretener, 1967; Thorne and Lewin, 1979; Lehre, 1982; White and Pickett, 1985; DeCelles, 1988; Morton, 1988; Piper et al., 1988; Brunsden, 1996; Church, 1996; House and Hirschboeck, 1997; Crozier, 1999; Dikau, 1999; Trustrum et al., 1999; Sivapalan, 2003). It is not always clear which combination of factors produces the resulting

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Jordan A. Clayton geomorphic form (Crowder and Knapp, 2005). Moreover, geomorphic systems may have complex responses to inputs that influence the nature of a system’s reaction from the mutual adjustment of forms and processes (Schumm, 1973; Brunsden and Thornes, 1979; Graf, 1988; Simon, 1989; Hooke and Redmond, 1992; Crozier, 1999). Graf (1988) emphasizes the importance of interdependencies between processes. Autogenic, or intrinsic, changes in the system are not accounted for by measuring input magnitudes (Schumm, 1975; Anhert, 1988, Richards, 1999). Positive feedbacks, such as with gully formation, may cause the system’s deviations from mean conditions to increase over time (Bull, 1975; Brunsden and Thornes, 1979; Scheidegger, 1987; Wilson, 1997). Typical quantitative models consider only the influence of one factor, such as the applied shear stress, on a given landform’s development. However, in many cases the magnitude of the landscape response to an input is a function of multiple interacting preparatory factors (e.g. “a process affecting the morphology of natural streams [in between flood hydrographs] is vegetal encroachment between floods” Parker et al., 2003, p. 890). 4) Quantitative models frequently imply a unidirectional cause-effect relationship between the process inputs and the form outputs, and not vice versa. This is an oversimplification. Forms have a pronounced effect on their own processes (Schumm and Lichty, 1965; Thorne and Lewin, 1979; Richards, 1999; Miller et al., 2001), and smaller landforms may be superimposed on larger or relict forms in a “landform palimpsest” (Higgins, 1975; Baker, 1977; Scoffin, 1993; Knox, 1996; Miller and Ritter, 1996; Dikau, 1999; Pethick and Crooks, 2000). 5) Quantitative models tend not to incorporate temporal variations in local geologic and climatic boundary conditions (Melton, 1962; Brunsden, 1980; Anhert, 1988; Loope et al., 1995; Trustum et al., 1999; Whitlock, 1999; Cannon, 2001; Meyer et al., 2001). Schumm (1975), Wolman and Gerson, (1978), Starkel (1999) and many others have noted the importance of local climatic and geologic constraints on both the magnitude and frequency curves in the original Wolman and Miller (1960) model. The frequency relations of disturbance events may change because the series is not necessarily stationary in time (Knox et al., 1975; Brunsden, 1996; Goudie and Viles, 1999). For example, in arid environments, vegetative recovery will proceed more slowly than in a humid climate, thereby increasing the lag time to system recovery (Wolman and Gerson, 1978). Also, the growth rate of a given vegetation type may increase with disturbance magnitude, thereby affecting the system’s recovery time (Leopold et al., 1964; Canham and Marks, 1985). For an unchanging system, these climatic and geologic variables are less important because the disturbance frequency curves can be derived empirically and locally. However, these variables are not typically static in natural systems. 6) Quantitative models of landscape change tend to be inherently uniformitarian, while ignoring catastrophic or other important singular events in a landscape’s history. A few words are given here regarding the differences between these two camps of thought to provide some context on this point. As emphasized by Gould (1984), both uniformitarianism and catastrophism assume a uniformity of physical laws and processes over time. In other words, modern landscapes can be explained within the same mechanical constraints as in times past, and that processes occurring presently can be assumed to have also occurred formerly. Where the two camps separate is in

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the uniformity of rate, wherein the rate of processes is assumed by uniformitarians to have held somewhat constant over time (Gould, 1984). In contrast, a catastrophist argument would maintain that periodic large disturbances upset system balances and lead to some, if not all, of the observable landscape features today. The geologic community has been slow to modify its uniformitarian foundation, perhaps due to misconceptions about the theory itself (Gould, 1984), the historical importance of the uniformitarian principle in the advancement of geologic thought and as a science, or a lack of appreciation of the importance of extreme events stemming from their rarity, lack of preservation, or complete absence in human time scales (Gretener, 1967; Clifton, 1988). For example, Higgins (1975) has commented that one of the reasons why the geomorphic cycles described by W.M. Davis were so influential in the first half of the 20th Century was due to the importance of the uniformitarian principles to the geologic community. The magnitude-frequency model presented by Wolman and Miller (1960) is strictly uniformitarian in that it does not allow for variations in process rates over time (Selby, 1974). Although large, unusual events are incorporated into the magnitude-frequency analysis, the long-term evolution of a system is thought to be the result of slow, unidirectional, gradual change from relatively frequent events. Crozier (1999, p. 36) explains that the model “provides a rationale for extrapolating short-term measurements of episodic processes over longer periods, as a way of assessing the long-term rates of geomorphic processes”. This is a fundamentally uniformitarian perspective (Marvin, 1990). As examples of catastrophism are increasingly manifest in our field observations, the concept of uniformity of rate for all geologic processes becomes suspect (see also discussion in Kennedy, 2001). 7) Extreme disturbance events may produce fundamentally different kinds of landforms (Baker, 1974; 1977; Selby, 1974; Wolman and Gerson, 1978; Brunsden, 1980; Kelsey, 1982b; Kehew and Lord, 1986; Clifton, 1988; Morton, 1988; Moore and Moore, 1988; Pilkey, 1988; Garcia, 1995; Benito, 1997; Starkel, 1999; Thomas, 1999; Magilligan et al., 2002). Wolman and Miller (1960, p. 71) note this deficiency in their model with examples of enduring disturbances such as landslides, gullies, avulsions, meander cut-offs, huge boulder deposits, etc. Some recent papers have stressed the importance of rare, large magnitude events in other geomorphological arenas (Lehre, 1982; Pethick and Crooks, 2000; Moody and Martin, 2001).

QUALITATIVE GEOMORPHIC MODELS AND DIMENSIONALITY To aim of this paper is not to champion qualitative models of landscape change at the expense of their quantitative counterparts. Qualitative models also tend to have many inherent shortcomings, such as the difficulty or outright inability to use them predictively and the obvious limitations for site assessment and analysis- exemplified by the well-documented drawbacks of the Davisian cycle of landscape evolution (1899). However, a useful potential feature of a qualitative conceptualization of landscape change is the ability to nondimensionalize the problem. To elaborate, quantitative models, like the magnitude-frequency concept, suffer from the fact that they account for only one or two of the many dimensions

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that may affect an evolving landscape, leading to the host of limitations listed in the section above. The more dimensions that are incorporated into such models, the better the contextualization but the more limited the transferability and universality of the findings (Church, 1996). However, and perhaps ironically, the removal of all dimensions from the inquiry in a qualitative model may lead to an increased ability to incorporate geographic and temporal context, and may also improve the transferability and universality of the results; this relationship is conceptually illustrated in Figure 1. While the potential to treat a given geomorphic problem quantitatively increases with the number of dimensions considered in a given study, the likelihood that the results of the study will be transferable should decrease (e.g. Simon and Rinaldi, 2006). Examples of effectively dimensionless, qualitative models of landscape change are given in Selby (1974), Graf, (1977), Wolman and Gerson (1978), Brunsden and Thornes (1979), Bull (1979, 1991), Pethick and Crooks (2000), and many others. The disturbance geomorphology model described in the next section attempts to assemble useful components of these models into a single, comprehensive conceptualization of landscape change.

Figure 1. Dimensionality, universality, and quantitative potential.

THE DISTURBANCE GEOMORPHOLOGY CONCEPT AS A QUALITATIVE, DIMENSIONLESS MODEL This section integrates key aspects from several previous geomorphic models (see above) into a single, qualitative model of landscape change over time that allows for the comparison of relative landscape development across varying scales and locations. The role of disturbances of varying magnitudes is of key interest. Geomorphologists have grown increasingly appreciative of the importance of discrete/extreme geologic events in shaping the earth surface, as noted above. The model presented in this section incorporates multiple system scales and geomorphic event magnitudes by focusing upon pulses of landscape stability and variations in system response to inputs. Landscape development is herein

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expressed in terms of residence times, sensitivity, resistance, tolerance, thresholds, response lags, and recovery periods (Schumm, 1973; Graf, 1977; Wolman and Gerson, 1978; Brunsden and Thornes, 1979; Kelsey, 1982a; Bull, 1991; Brunsden, 1996; Crozier, 1999; Gregory, 2006; and many others). Collectively termed herein as “disturbance geomorphology”, these concepts can be universalized to most situations despite differences in geography, process, and temporal and spatial scale. A geomorphic system is thought to be the result of a series of processes interacting at different rates and areas, called the process domain (Brunsden and Thornes, 1979; Brunsden, 1996; Montgomery, 1999; Wohl, 2006), manifest as either individual landforms or landform assemblages. To avoid ambiguity, the terms “landform”, “episode”, and “disturbance” are defined as follows. Landforms are any feature of the lithosphere with a definable and differentiable form (similar to Renwick, 1992). This includes erosional and depositional features, fullydeveloped and transitional features, and both small and continental-scale forms. In most cases they are naturally-occurring, but this definition does not exclude human-made landforms per se. Episodes are any punctual, pulsed, convulsive, extreme, or catastrophic events in landform development. Episodes in this context are not equated with the crossing of process domain thresholds and may occur commonly. As such, landforms that may have initially been in equilibrium with their process domain (in the sense of Langbein and Leopold, 1964) may return to an equilibrium condition (e.g. Pitlick, 1993). Minor disturbances are episodes that cause a permanent shift, or non-recovery, in the geomorphic conditions of a system but the process thresholds remain the same (e.g. Baker, 1977). Major disturbances are episodes that cause a system to cross into a different process domain, and it may not be possible for mean conditions to force the system to revert to its former process-domain (Brunsden and Thornes, 1979) (Figure 2). Both episodes and disturbances represent significant deviations from mean or modal (depending on the system) inputs that may lead to long-term shifts in form structure. Some examples of disturbances are: large floods, fires, avalanches and landslides, slope failures, large storms and hurricanes, meteorite impacts, natural dam failures, earthquakes and subsidence, volcanic eruptions, giant waves and tsunamis, jokalhaups, etc. These are examples of “formative events” as defined by Wolman and Gerson (1978, p. 190) and episode maintenance events, i.e. events that help to maintain a given condition. For brevity, biotic and human-related disturbances are not included here. Figure (2) illustrates several possible influences of episodes and disturbances on geomorphic change. According to this model, the process domains cover a discrete range of geomorphic change, meaning that a certain degree of change can be sustained before the dominant processes affecting a given geomorphic system are adjusted. Despite their appearance in the diagram, process domains are not necessarily consecutive nor meant to depict linear change. Furthermore, some possibilities are not represented, such as a progressive, positive-feedback response to a given disturbance and those landforms for which there may never be a characteristic or average morphology (Renwick, 1992).

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Figure 2. Disturbance geomorphology model showing variations of system response to episodes and disturbances. The thin, wavy line around the main line illustrates geomorphically insignificant system fluctuations around the dominant conditions (illustrated by the main line). PDx refers to a given process domain. Note that the geomorphic change is nonlinear, i.e. domain shifts may be directed from PDx to either PDx+1 or PDx-1. (a) Episode with a lag before the system reaction, reaction time necessary before episode effects are fully realized, residence time at altered geomorphology, and recovery time necessary to return to initial conditions. All of these are components of the overall response time, and there is a delay before the next episode. (b) Multiple episodes with a secondary episode occurring earlier than the response time. The second curve shows a possible dual response and/or domain shift. Dual responses and domain shifts may follow either multiple episodes or one or more disturbances. (c) Minor disturbance leading to a non-recovery of the initial conditions. (d) Major disturbance leading to a domain shift and domain recovery. (e) Major disturbance leading to a sustained domain shift. The order of (a-e) was chosen arbitrarily. Modified from Graf (1977), Wolman and Gerson (1978), Brunsden and Thornes (1979), Bull (1979; 1991), Brunsden (1980; 1996), Kelsey (1982a), Knighton (1998), Crozier (1999), Pethick and Crooks (2000), Gregory (2006), and Clayton and Westbrook (2008).

The total amount of time required for a landform or geomorphic system to recover from a given episode is referred to as the response time, and the duration until the next episode after complete recovery is termed the delay time (Figure 2). Sometimes an episode does not elicit an immediate response, thus the time taken before the system notably responds is the lag time. Different episodes will have different reaction, residence, and recovery times, or the amount of time required until the system has reached its maximum response, the duration of maximum change before recovery, and the amount of time required to return to the baseline conditions respectively. Multiple episodes or disturbances may occur before the total response time has elapsed, resulting in a more complex system alteration. In some instances the system may exhibit a dual response, wherein the system elements become bifurcated and

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consequently respond to the given process domain in two unique fashions (e.g. Field, 2001). Another possibility is that the geomorphic system will respond by switching to a different process domain, termed a domain shift (sensu Schumm, 1979), and will then either recover to the former process domain, called a domain recovery, or remain permanently in the new process domain. It should not be assumed, however, that these scenarios are thought to occur progressively. Rather, the order of (a-e) was chosen arbitrarily. Real-world examples of the features presented in Figure 2 are given in the following section. The advantages of the disturbance geomorphology approach are as follows: (1) it is a dimensionless model that can still incorporate a feature’s geographical and/or temporal framework, the importance of which was described above; (2) it is non-deterministic; (3) it can handle complex geomorphic responses (Schumm and Lichty, 1965; Simon, 1989); (4) multiple system inputs can result in one output, and vice versa; (5) it is not constrained by, nor opposed to, uniformitarianism, nor does it suppose static or regularly-occurring environmental conditions; and (6) it uses terminology that is roughly consistent with similar qualitative models of geomorphic change (e.g. Graf, 1977; Wolman and Gerson, 1978; Brunsden and Thornes, 1979; Hardisty, 1987; Bull, 1991; Chin, 2006; and many others).

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CASE STUDIES To further illustrate the disturbance geomorphology model, three case studies (an episode, a minor disturbance, and a major disturbance) and their geomorphic responses are examined. These case studies were chosen specifically to highlight the use of the disturbance geomorphology model in assessing landscape response. (1) Case study of an episode: the Buffalo Creek Fire in Colorado and its geomorphic response. The 1996 Buffalo Creek Fire of central Colorado burned nearly 5000 ha of ponderosa pine and Douglas fir forest in two adjacent watersheds. Subsequent large rain storms in the summer of 1996 caused massive flash flooding and debris movement, resulting in the development of interrill erosion, rills, gullies, and sedimentation in low-gradient channels and reservoirs (Moody and Martin, 2001; Elliott and Parker, 2001). Although extreme by historical standards, the fire may have had recent geologic analogs, evidenced from radiocarbon dates of former sedimentation episodes ranging 2900 yr BP. Moody and Martin (2001) estimated the residence time of fire-derived sediment stored in low-lying areas to be around 300 years, whereas the recurrence frequency of wildfires may be as little as 2050 years. They concluded that the depositional features introduced by this disturbance may be persistent components of the local geomorphology. Conversely, erosional features may be obscured within 3-4 years of a given fire-storm sequence, which is less than the recurrence interval for fires in the Colorado Front Range, and thus minimizes their importance in the region’s long-term geomorphic appearance (Moody and Martin, 2001). In our terms, the fire and subsequent storm combined to cause a geomorphicallysignificant episode with several of the features shown in Figure 2. The reaction time was nearly instantaneous and caused a dual response: hillslope erosion and basin sedimentation had differing residence times and recovery rates. In fact, the massive deposition of material into low-lying areas should be considered a minor disturbance if the imprint significantly altered the geomorphology of the valley floor. Note the importance of antecedent conditions

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(readiness for the forest to burn), possible synergetic processes (fire and rain storm combination), local geology (weathered granitic bedrock and thin soils), landscape position (hillslope versus valley bottom), and other local variables in producing this landscape. (2) Case study of a minor disturbance: the giant waves of Lituya Bay, Alaska. Lituya Bay is a 220 meter deep, 11 km long fjord located along the northeast shore of the Gulf of Alaska. On July 9th, 1958, approximately 3.0 x 107 m3 of rock collapsed into the bay’s inlet from as high as 914 m above sea level (Miller, 1960). This resulted in a massive gravity wave, estimated to have reached a maximum shoreline elevation of 524 m and traveled at velocities approaching 210 kph, killing two people and many marine plants and animals, and destroying around 4 km2 of boreal forest. The wave removed around 3.0 x 106 m3 of sediment over the entire affected area, cut cliffs and cut banks, and exposed large areas of bedrock. From eyewitness accounts and the positions of former trimlines (as far as 1100 horizontal meters from the shoreline in some locations), Miller (1960) estimated that there have been at least four giant waves in the bay since around 1850. Possible causes of the former waves include the sudden drainage of upstream pro-glacial lakes, nearby fault displacement, repeated rockslides or avalanches, submarine landsliding, or sudden movement of the North Crillon Glacier which terminates in Lituya Bay. Each wave resulted in massive scouring, steepening of the banks, vegetative removal, and the creation of trimlines. The giant waves in Lituya Bay should be considered to be minor disturbances (Figure 2c). Each event causes a radical shift in the bay’s landscape and leaves a permanent imprint. The loss of vegetation slows the stabilization of the shorelines. The waves occur at a recurrence interval of roughly 25 to 30 years, and the recovery time is certainly much greater. Miller (1960) describes the mapping of the location of a 1936 giant wave by geologists in 1952, and was able to find wave-generated oversteepened slopes several years later. Thus, the geomorphology of Lituya Bay may be thought of as a sensitive system (as described later) with superimposed landforms from the repeated events. The waves do not represent major disturbances, however, because the fundamental processes affecting the regional morphological evolution include the impacts of the waves, and thus, do not constitute a process domain shift. (3) Case study of a major disturbance: the Mount Mazama eruption and Crater Lake, Oregon. The eruption of Mount Mazama around 6900 yr BP has been described as the “most significant convulsive sedimentary event in North America during Holocene time” (Nelson et al., 1988, p. 37). The eruption resulted in the formation of a 10 km wide, 366 m deep collapse caldera, the distribution of pyroclastic ash over a 1.0 x 106 km2 area- in some places as far as 2000 km away, and the development of smaller craters along a fracture zone at the base of the caldera (Nelson et al., 1988). Today, Crater Lake fills the basin to depths of 620 m and is surrounded by steep (~45º) 150 to 600 m high walls. Since their initial formation, the crater walls have been subject to repeated failures, evidenced by the accumulation of rotated blocks and rubble upon the basin floor (Nelson et al., 1988). The eruption of Mount Mazama was clearly a major disturbance, causing massive landscape change and an alteration in the principle processes affecting the region’s morphology (Figure 2e). It is not likely that the system will experience a domain return, i.e. the effects of this disturbance were of a sufficient magnitude to cause a permanent system modification. This eruption was a singular, catastrophic event with far-reaching consequences for large areas of North America.

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These case studies should not imply that episodes and disturbances cannot occur on timescales different than those presented, or that it takes a cataclysmic volcanic eruption to generate a major disturbance. Other examples, such as the event described by Griffin and Smith (1999), illustrate that major disturbances also occur under human timescales and noncalamitous disturbance magnitudes; countless other examples apply.

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SENSITIVITY OF LANDFORMS AND LANDSCAPES TO CHANGE An alternate presentation of Figure 2 might include a comparison between a system lying within the graphical center of its process domain and another operating near the margins. The system operating near the margins would therefore be more sensitive to a given size episode or disturbance because a smaller event would be required to force the system into a neighboring process domain. Others have conceptualized the sensitivity of a given landform to geomorphic change metaphorically as a ball that rests either atop a dome or at the bottom of a bowl; the necessary force required to enact movement of the ball is thereby linked to its locational context (Brunsden and Thornes, 1979; Nanson and Huang, 2008). Brunsden and Thornes (1979) developed a dimensionless index of landscape sensitivity to change where the sensitivity of a given landform is expressed as a ratio between the reaction time, or amount of time needed to obtain a definitive and differentiable form, and the event frequency (see also Pethick and Crooks, 2000). While conceptually useful, determination of the reaction time at any location requires accounting for that location’s geographic context. Moreover, determination of the event frequency is made difficult by many of the same contextual issues previously discussed in the context of the magnitude-frequency model, such as the importance of antecedent conditions, event clustering, changes in frequency over time, etc. Another possibility would be to equate sensitivity to rapidity of response; landscapes that are more sensitive to geomorphic change should respond more quickly to a given size event. A theoretical index of system sensitivity, then, might be determined by the ratio of the lag time divided by the response time, as defined above. This ratio should increase with the spatial extent of the affected geomorphic area, i.e. stability may be expected to increase with system size or other boundary conditions (Wolman and Gerson, 1978; Simon and Darby, 1997; Crozier, 1999). Alternatively, in many geomorphic systems, disturbance frequency may be an appropriate measure of system response. If so, the relevant temporal components of this or other sensitivity ratios should be computed. Unfortunately, it is currently difficult, if not impossible, to develop statistically-significant relations between sensitivity indexes and geomorphic characteristics due to the lack of sensitivity-type data and short observation periods at most locations. However, where possible such results would have utility for the assessment and management of environmental hazards. However, sensitivity is also affected by the magnitude and duration of various barriers or filters to change (Brunsden and Thornes, 1979; Yu and Wolman, 1987; Kochel, 1988; Crozier, 1999) which also vary over time (Brunsden, 1980; Lawson, 1986; Crozier and Preston, 1999). A given system may become more stable as the potential energy for system adjustment decreases solely due to an increase in the size of the barriers to change (Brunsden, 2001). This illustrates a sensitivity continuum between two end members: (1) systems that respond quickly and easily to episodes, and (2) insensitive systems wherein the magnitude of

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the boundaries to change are insurmountable by the system stresses. More sensitive systems will tend to have a greater abundance of transient or superimposed landforms than their insensitive counterparts (Brunsden and Thornes, 1979; Anderson and Sambles, 1988; Montgomery and Buffington, 1997). Also, the ability of a system to recover may depend upon its elasticity, or the degree to which its new conditions differ from the former ones (Brunsden, 1996). Minor disturbances may result from fairly ordinary geomorphic events if the impacted system has low elasticity; graphically, this would refer to the relative change in the y-axis of Figure 2 from the initial to changed conditions after a minor disturbance.

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CONCLUSION: RECONCILING QUALITATIVE AND QUANTITATIVE GEOMORPHIC MODELS A primary limitation (and strength) of quantitative geomorphic models is that their application is necessarily empirical. Researchers have repeatedly shown that local, empirically-based field studies may be able to adequately evaluate landscape change at a particular site in a quantitative, directional manner, and that the magnitude-frequency model may very accurately model landform development for certain situations (Selby, 1974; Clifton, 1988). For example, in systems with continuous inputs, occasional variations in the magnitudes of those inputs, adequate delay time between larger events, and with somewhat unidirectional and deterministic process inputs and outputs, the Wolman and Miller (1960) model may be used without reservation (e.g. Andrews, 1980; Torizzo and Pitlick, 2004). Some examples suggested by Wolman and Miller (1960) include humid rivers, beach modification, and dune development. However, the constraints of locally-varying climatological and geological environments, antecedent disturbance histories, dominant process domains, and other factors preclude the indiscriminate application of quantitative models to landscape change at the process level (see discussion in Fuller, 2007). Therefore, while it appears to remain impossible to develop a universal, quantitative model of landscape evolution independent of locally-important relationships, it is possible to develop general, and statistically-significant, empirical statements about landscape stability in different areas. This requires that geomorphic systems under analysis be investigated in the field or in site-specific models in order to establish meaningful relationships between the dominant processes and their effects. Yet, it is this author’s contention that that the methods of landscape change are generally the same for all geomorphic situations despite their variations in quantitative application and can be represented by a continuum of landscape adjustment, ranging from continual adjustment to those landscapes dominated by catastrophic events, with uniformitarian systems in between (Schumm, 1988). At one end of the spectrum, many gravity and weatheringdriven geomorphic process act continuously to modify the landscape; these are not explicitly represented in the disturbance geomorphology model. Next are the uniformitarian systems, wherein repeated, fairly predictable pulses of adjustment occur with enough regularity and with moderate enough variability in output magnitude to enable their geomorphic footprint to be predicted within reasonable bounds. In this way, the episodes described by the disturbance geomorphology model act as uniformitarian agents of landscape change. Finally, disturbance-dominated systems retain the imprint of singular and/or catastrophic geologic

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events, even while being modified by continual and/or uniformitarian processes, because the process domain within which these contemporary processes act is still determined by the legacy of the former event(s). I have attempted to outline some of the deficiencies of typically-employed quantitative models with the aim towards developing a broader, qualitative approach, as well as to demonstrate how the two may be reconciled for particular investigations. Moreover, I have underscored the importance of geographic context in geomorphic studies, and provided a qualitative, conceptual model that increases the transferability of individual findings due, in part, to its dimensionlessness and its flexibility in application. Quantitative investigations may benefit by contextualizing their findings within the theoretical framework provided by the disturbance geomorphology model or other qualitative models of geomorphic adjustment.

ACKNOWLEDGEMENTS The disturbance geomorphology model draws together ideas from Graf (1977), Wolman and Gerson (1978), Brunsden and Thornes (1979), Brunsden (1980; 1996), Kelsey (1982a), Hardisty (1987), Clifton (1988), Knighton (1998), Crozier (1999), Richards (1999), Pethick and Crooks (2000), and many other crucially important papers. Additional references on related topics may be found in Fuller (2007). John Pitlick reviewed a much earlier version of this manuscript and provided many useful comments.

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REFERENCES Anderson, M.G. and Sambles, K.M., 1988, A review of the bases of geomorphological modelling. In: M.G. Anderson (editor), Modelling geomorphological systems. J. Wiley & Sons Ltd. pp. 1-32. Baker, V.R., 1977, Stream-channel response to floods, with examples from central Texas. Geological Society of America Bulletin, v. 88. pp. 1057-1071. Benito, G., 1997, Energy expenditure and geomorphic work of the cataclysmic Missoula flooding in the Columbia River Gorge, USA. Earth Surface Processes and Landforms, v. 22. pp. 457-472. Brunsden, D., 1980, Applicable models of long term landform evolution. Zeitschrift fur Geomorphologie, Suppl. Bd. 36. pp. 16-26. Brunsden, D., 1996, Geomorphological events and landform change. Zeitschrift fur Geomorphologie, v. 40, n. 3. pp. 273-288. Brunsden, D., 2001, A critical assessment of the sensitivity concept in geomorphology. Catena, v. 42. pp. 99-123. Brunsden, D. and Thornes, J.B., 1979, Landscape sensitivity and change. Transactions of the Institute of British Geogr., v. 4, n. 4. pp. 463-484. Bull, W.B., 1975, Landforms that do not tend toward a steady state. In: W.C. Melhorn and R.C. Flemal (editors), Theories of Landform Development. Proc. of 6th Ann. Geom. Symp. Ser., Binghampton, NY. pp. 111-128.

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Bull, W.B., 1979, Threshold of critical power in streams. Geological Society of America Bulletin, v. 90. pp. 453-464. Bull, W.B., 1991, Geomorphic responses to climate change. Oxford University Press, New York. 326 p. Canham, C.D. and Marks, P.L., 1985, The response of woody plants to disturbance: patterns of establishment and growth. In: S.T.A. Pickett and P.S. White (editors), The Ecology of natural disturbance and patch dynamics. Academic Press, Inc. pp. 197-216. Cannon, S.H., 2001, Debris-flow generation from recently burned watersheds. Environmental and Engineering Geoscience, v. 7, n. 4. pp. 321-341. Chin, A., 2006, Urban transformation of river landscapes in a global context. Geomorphology, v. 79. pp. 460-487. Chorley, R.J., 1978, Bases for theory in geomorphology. In: C. Embleton, D. Brunsden, and D.K.C. Jones (editors), Geomorphology: Present problems and future prospects. Oxford U. Press. pp. 1-13. Church, M., 1996, Space, time and the mountain – how do we order what we see? In: B.L. Rhoads and C.E. Thorn (editors), The scientific nature of geomorphology: Proceedings of the 27th Binghampton Symposium in Geomorphology held 27-29 September 1996. J. Wiley and Sons Ltd. pp. 147-170. Clayton, J.A. and Westbrook, C.J., 2008, The effect of the Grand Ditch on the abundance of benthic invertebrates in the Colorado River, Rocky Mountain National Park. River Research and Applications, v. 24, n. 7. DOI: 10.1002/rra.1117. pp. 975-987. Clifton, H.E., 1988, Sedimentologic relevance of convulsive geologic events. In: H.E. Clifton (editor), Sedimentologic consequences of convulsive geologic events. Geological Society of America, Special Paper 229. pp. 1-5. Costa, J.E. and O’Connor, J.E., 1995, Geomorphically effective floods. In: J.E. Costa, A.J. Miller, K.W. Potter, and P.R. Wilcock (editors), Natural and Anthropogenic influences in fluvial geomorphology: The Wolman Volume. American Geophysical Union, Geophysical Monograph 89. pp. 45-56. Crowder, D.W. and Knapp, H.V., 2005, Effective discharge recurrence intervals of Illinois streams. Geomorphology, v. 64. pp. 167-184. Crozier, M.J., 1999, The frequency and magnitude of geomorphic processes and landform behaviour. In: M. Crozier and R. Mausbacher (editors), Magnitude and frequency in Geomorphology. Proceedings of the 4th Intl. Conference on Geomorphology, Bologna. Zeitschrift fur Geomorphologie, Supplementband 115. pp. 35-50. Crozier, M.J. and Preston, N.J., 1999, Modelling changes in terrain resistance as a component of landform evolution in unstable hill country. In: S. Hergarten and H.J. Neugebauer (editors), Process modelling and landform evolution. Lecture Notes in Earth Sciences 78. Springer-Verlag. pp. 267-284. Davis, W.M., 1899, The geographic cycle. Geographical journal, v. 14. pp. 481-504. DeCelles, P.G., 1988, Deposits of a middle Tertiary convulsive geologic event, San Emigdio Range, southern California. In: H.E. Clifton (editor), Sedimentologic consequences of convulsive geologic events. Geological Society of America, Special Paper 229. pp. 127142. Dikau, R., 1999, The need for field evidence in modelling landform evolution. In: S. Hergarten and H.J. Neugebauer (editors), Process modelling and landform evolution. Lecture Notes in Earth Sciences 78. Springer-Verlag. pp. 3-12.

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Geomorphic Adjustment, Geographic Context, and Disturbances

111

Elliott, J.G. and Parker, R.S., 2001, Developing a post-fire chronology and recurrence probability from alluvial stratigraphy in the Buffalo Creek watershed, Colorado, USA. Hydrological Processes, v. 15. pp. 3039-3051. Emmett, W.M. and Wolman, M.G., 2001, Effective discharge and gravel-bed rivers. Earth Surface Processes and Landforms, v. 26. pp. 1369-1380. Field, J., 2001, Channel avulsion on alluvial fans in southern Arizona. Geomorphology, v. 37. pp. 93-104. Fryirs, K. and Brierley, G.J., 2001, Variability in sediment delivery and storage along river courses in Bega catchment, NSW, Australia: implications for geomorphic river recovery. Geomorphology, v. 38. pp. 237-265. Fucella, J.E. and Dolan, R., 1996, Magnitude of subaerial beach disturbance during Northeast storms. Journal of Coastal Research, v. 12, n. 2. pp. 420-429. Fuller, I.C., 2007, Geomorphic work during a “150-Year” storm: contrasting behaviors of river channels in a New Zealand Catchment. Annals of the Association of American Geographers, v. 97. pp. 665-676. Garcia, C.C., 1995, Torrential flow frequency and morphological adjustments of ephemeral channels in south-east Spain. In: E.J. Hickin (editor), River Geomorphology. J. Wiley & Sons, Ltd. pp. 169-192. Goudie, A.S. and Viles, H.A., 1999, The frequency and magnitude concept in relation to rock weathering. In: M. Crozier and R. Mausbacher (editors), Magnitude and frequency in Geomorphology. Proceedings of the 4th Intl. Conference on Geomorphology, Bologna. Zeitschrift fur Geomorphologie, Supplementband 115. pp. 175-189. Gould, S.J., 1984, Toward the vindication of punctual change. In: W.A. Berggren and J.A. Van Couvering (editors), Catastrophes and Earth history. Princeton University Press, N.Y. pp. 9-34. Graf, W.L., 1977, The rate law in fluvial geomorphology. American Journal of Science, v. 277. pp. 178-191. Graf, W.L., 1979, Catastrophe theory as a model for change in fluvial systems. In: D.D. Rhodes and G.P. Williams (editors), Adjustments of the fluvial system. Kendall-Hunt. pp. 13-32. Graf, W.L., 1988, Applications of catastrophe theory in fluvial geomorphology. In: M.G. Anderson (editor), Modeling geomorphological systems. J. Wiley & Sons Ltd. pp. 33-47. Gregory, K.J., 2006, The human role in changing river channels. Geomorphology, v. 79. pp. 172-191. Gretener, P.E., 1967, Significance of the rare event in geology. American Association of Petroleum Geologists, v. 51, n. 11. pp. 2197-2206. Gretener, P.E., 1984, Reflections on the "Rare event" and related concepts in geology. In: W.A. Berggren and J.A. Van Couvering (editors), Catastrophes and Earth history. Princeton University Press, N.Y. pp. 77-89. Griffin, E.R. and Smith, J.D., 1999, Change in planiform geometry of a small meandering river when subjected to an extreme flood. Eos Trans. AGU, 1999 Fall Meet. Suppl., Abstract H42B-13. Hardisty, J., 1987, The transport response function and relaxation time in geomorphic modelling. In: F. Anhert (editor), Geomorphological models: Theoretical and empirical aspects. Catena Supplement 10. pp. 171-179.

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112

Jordan A. Clayton

Higgins, C.G., 1975, Theories of landscape development: a perspective. In: W.C. Melhorn and R.C. Flemal (editors), Theories of Landform Development. Proc. of 6th Ann. Geom. Symp. Ser., Binghampton, NY. pp. 1-28. Hooke, J.M. and Redmond, C.E., 1992, Causes and nature of river planform change. In: P. Billi, R.D. Hey, C.R. Thorne., and P. Tacconi (editors), Dynamics of Gravel-bed rivers. J. Wiley & Sons Ltd. pp. 557-571. House, P.K. and Hirschboeck, K.K., 1997, Hydroclimatological and paleohydrological context of extreme winter flooding in Arizona, 1993. In: R.A. Larson and J.E. Slosson (editors), Storm-Induced Geologic Hazards: Case histories from the 1992-1993 winter in southern California and Arizona. Geological Society of America, Reviews in Engineering Geology, v. XI. pp. 1-24. Howard, A.D., 1988, Equilibrium models in geomorphology. In: M.G. Anderson (editor), Modelling geomorphological systems. J. Wiley & Sons Ltd. pp. 49-72. Hoyle, J., Brooks, A., Brierley, G., Fryirs, K., and Lander, J., 2008, Spatial variability in the timing, nature and extent of channel response to typical human disturbance along the Upper Hunter River, New South Wales, Australia. Earth Surface Processes and Landforms, v. 33. pp. 868-889. Ibsen, M.L. and Bromhead, E.N., 1999, Head scarps and toe heaves. In: M. Crozier and R. Mausbacher (editors), Magnitude and frequency in Geomorphology. Proceedings of the 4th Intl. Conference on Geomorphology, Bologna. Zeitschrift fur Geomorphologie, Supplementband 115. pp. 125-139. Kehew, A.E. and Lord, M.L., 1986, Origin and large-scale erosional features of glacial-lake spillways in the northern Great Plains. Geological Society of America Bulletin, v. 97. pp. 162-177. Kelsey, H.M., 1982a, Influence of magnitude, frequency, and persistence of various types of disturbance on geomorphic form and process. In: F.J. Swanson, R.J. Janda, T. Dunne, and D.N. Swanston (editors), Sediment budgets and routing in forested drainage basins. U.S. Dept. of Agriculture Forest Service General Technical Report PNW 141. pp. 150-153. Kelsey, H.M., 1982b, Hillslope evolution and sediment movement in a forested headwater basin, Van Duzen River, North Coastal California. In: F.J. Swanson, R.J. Janda, T. Dunne, and D.N. Swanston (editors), Sediment budgets and routing in forested drainage basins. U.S. Dept. of Agriculture Forest Service General Technical Report PNW 141. pp. 86-96. Kennedy, B.A., 2001, Charles Lyell and ‘Modern changes of the Earth’: the Milledgeville Gully. Geomorphology, v. 40. pp. 91-98. Knighton, D., 1998, Fluvial forms and processes: A new perspective. J. Wiley & Sons, Inc., N.Y. 383 p. Knox, J.C., 1996, Late Quaternary upper Mississippi alluvial episodes and their significance to the lower Mississippi River system. Engineering Geology, v. 45. pp. 263-285. Knox, J.C., Bartlein, P.J., Hirschboeck, K.K., and Muckenhirn, R.J., 1975, The response of floods and sediment yields to climate variation and land use in the Upper Mississippi Valley. IES Report 52, Institute for Environmental Studies, University of Wisconsin, Madison. 76 p. Kochel, R.C., 1988, Geomorphic impact of large floods: Review and new perspectives on magnitude and frequency. In: V.R. Baker, R.C. Kochel, and P.C. Patton (editors), Flood geomorphology. John Wiley and Sons, New York. pp. 167-187.

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Geomorphic Adjustment, Geographic Context, and Disturbances

113

Lane, S.N. and Richards, K.S., 1997, Linking river channel form and process: time, space and causality revisited. Earth surface processes and landforms, v. 22. pp. 249-260. Langbein, W.B. and Leopold, L.B., 1964, Quasi-equilibrium states in channel morphology. American Journal of Science, v. 262. pp. 782-794. Lawson, D.E., 1986, Response of permafrost terrain to disturbance: A synthesis of observations from northern Alaska, U.S.A. Arctic and Alpine Research, v. 18, n. 1. pp. 117. Lehre, A.K., 1982, Sediment budget of a small coast range drainage basin in north-central California. In: F.J. Swanson, R.J. Janda, T. Dunne, and D.N. Swanston (editors), Sediment budgets and routing in forested drainage basins. U.S. Dept. of Agriculture Forest Service General Technical Report PNW 141. pp. 67-77. Leopold, L.B., Wolman, M.G., and Miller, J.P., 1964, Fluvial processes in geomorphology. W.H. Freeman & Co., San Francisco. 522 p. Loope, D.B., Swinehart, J.B., and Mason, J.P., 1995, Dune-dammed paleovalleys of the Nebraska Sand Hills: Intrinsic versus climatic controls on the accumulation of lake and marsh sediments. Geological Society of America Bulletin, v. 107, n. 4. pp. 396-406. Magilligan, F.J., 1992, Thresholds and the spatial variability of flood power during extreme floods. Geomorphology, v. 5. pp. 373-390. Magilligan, F.J., Gomez, B., Mertes, L.A.K., Smith, L.C., Smith, N.D., Finnegan, D., and Garvin, J.B., 2002, Geomorphic effectiveness, sandur development, and the pattern of landscape response during jokulhlaups: Skeidararsandur, southeastern Iceland. Geomorphology, v. 44. pp. 95-113. Marvin, U.B., 1990, Impact and its revolutionary implications for geology. In: V.L. Sharpton and P.D. Ward (editors), Global catastrophes in Earth history; An interdisciplinary conference on impacts, volcanism, and mass mortality. Geological Society of America, Special Paper 247. pp. 147-154. Matthews, E.R., 1983, Wave disturbance and texture of beaches in Palliser Bay, southern North Island, New Zealand. New Zealand Journal of Geology and Geophysics, v. 26. pp. 197-212. Melton, M.A., 1962, Methods for measuring the effect of environmental factors on channel properties. Journal of Geophysical Research, v. 67, n. 4. pp. 1485-1490. Meyer, G.A., Pierce, J.L., Wood, S.H., and Jull, A.J.T., 2001, Fire, storms, and erosional events in the Idaho batholith. Hydrological Processes, v. 15. pp. 3025-3038. Miller, A.J., 1988, What does it take to make a geomorphically effective flood? Some lessons from the November 1985 flood in West Virginia. Eos Transactions, v. 69, n. 16. pp. 347. Miller, D.J., 1960, Giant waves in Lituya Bay, Alaska. U.S. Geological Survey Professional Paper 354-C. 86 p. Miller, J.R. and Ritter, J.B., 1996, An examination of the Rosgen classification of natural rivers. Catena, v. 27. pp. 295-299. Miller, J., Germanoski, D., Waltman, K., Tausch, R., and Chambers, J., 2001, Influence of late Holocene hillslope processes and landforms on modern channel dynamics in upland watersheds of central Nevada. Geomorphology, v. 38. pp. 373-391. Montgomery, D.R., 1999, Process domains and the river continuum. Journal of the American Water Resources Association, v. 35. pp. 397-410. Montgomery, D.R. and Buffington, J.M., 1997, Channel-reach morphology in mountain drainage basins. Geological Society of America Bulletin, v. 109, n. 5. pp. 596-611.

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114

Jordan A. Clayton

Moody, J.A. and Martin, D.A., 2001, Initial hydrologic and geomorphic response following a wildfire in the Colorado Front Range. Earth Surface Processes and Landforms, v. 26. pp. 1049-1070. Moore, G.W. and Moore, J.G., 1988, Large-scale bedforms in boulder gravel produced by giant waves in Hawaii. In: H.E. Clifton (editor), Sedimentologic consequences of convulsive geologic events. Geological Society of America, Special Paper 229. pp. 101110. Morton, R.A., 1988, Nearshore responses to great storms. In: H.E. Clifton (editor), Sedimentologic consequences of convulsive geologic events. Geological Society of America, Special Paper 229. pp. 7-22. Nanson, G.C. and Huang, H.Q., 2008, Least action principle, equilibrium states, iterative adjustment and the stability of alluvial channels. Earth Surface Processes and Landforms, v. 33. pp. 923-942. Nelson, C.H., Carlson, P.R., and Bacon, C.R., 1988, The Mount Mazama climactic eruption (~6900 yr B.P.) and resulting convulsive sedimentation on the Crater Lake caldera floor, continent, and ocean basin. In: H.E. Clifton (editor), Sedimentologic consequences of convulsive geologic events. Geological Society of America, Special Paper 229. pp. 37-57. Pazzaglia, F.J., 2003, Landscape evolution models. Development in Quaternary Science, v. 1. pp. 247-274. Pethick, J.S. and Crooks, S., 2000, Development of a coastal vulnerability index: a geomorphological perspective. Environmental Conservation, v. 27, n. 4. pp. 359-367. Pickett, S.T.A. and White, P.S., 1985, Patch dynamics: a synthesis. In: S.T.A. Pickett and P.S. White (editors), The Ecology of natural disturbance and patch dynamics. Academic Press, Inc. pp. 371-384. Pilkey, O.H., 1988, Basin plains; giant sedimentation events. In: H.E. Clifton (editor), Sedimentologic consequences of convulsive geologic events. Geological Society of America, Special Paper 229. pp. 93-99. Piper, D.J.W., Shor, A.N., and Clark, J.E.H., 1988, The 1929 “Grand Banks” earthquake, slump, and turbidity current. In: H.E. Clifton (editor), Sedimentologic consequences of convulsive geologic events. Geological Society of America, Special Paper 229. pp. 77-92. Pitlick, J., 1993, Response and recovery of a subalpine stream following a catastrophic flood. Geological Society of America Bulletin, v. 105. pp. 657-670. Renwick, W.H., 1992, Equilibrium, disequilibrium, and nonequilibrium landforms in the landscape. Geomorphology, v. 5. pp. 265-276. Richards, K., 1999, The magnitude-frequency concept in fluvial geomorphology: a component of a degenerating research programme? In: M. Crozier and R. Mausbacher (editors), Magnitude and frequency in Geomorphology. Proceedings of the 4th Intl. Conference on Geomorphology, Bologna. Zeitschrift fur Geomorphologie, Supplementband 115. pp. 1-18. Scheidegger, A.E., 1987, The fundamental principals of landscape evolution. In: F. Anhert (editor), Geomorphological models: Theoretical and empirical aspects. Catena Supplement 10. pp. 199-210. Schumm, S.A., 1973, Geomorphic thresholds and complex response of drainage systems. In: M. Morisawa (editor), Fluvial geomorphology: Proceedings of the 4th Annual Geom. Symposia Series, Binghampton, N.Y. pp. 299-310.

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115

Schumm, S.A., 1975, Episodic erosion: A modification of the geomorphic cycle. In: W.C. Melhorn and R.C. Flemal (editors), Theories of Landform Development. Proc. of 6th Ann. Geom. Symp. Ser., Binghampton, NY. pp. 69-85. Schumm, S.A., 1979, Geomorphic thresholds: the concept and its applications. Transactions of the Institute of British Geographers, v. 4, n. 4. pp. 485-515. Schumm, S.A., 1988, Geomorphic hazards – problems of prediction. Zeitschrift fur Geomorphologie, v. 67. pp. 17-24. Schumm, S.A. and Lichty, R.W., 1965, Time, space, and causality in geomorphology. American Journal of Science, v. 263. pp. 110-119. Scoffin, T.P., 1993, The geological effects of hurricanes on coral reefs and the interpretation of storm deposits. Coral Reefs, v. 12. pp. 203-221. Scott, K.M., 1988, Origin, behavior, and sedimentology of prehistoric catastrophic lahars at Mount St. Helens, Washington. In: H.E. Clifton (editor), Sedimentologic consequences of convulsive geologic events. Geological Society of America, Special Paper 229. pp. 23-36. Showstack, R., 2002, Antarctic “Larsen B” ice shelf shatters. Eos, Transactions, v. 83, n. 14. pp. 158. Simon, A., 1989, Model of channel response in disturbed alluvial channels. Earth Surface Processes and Landforms, v. 14. pp. 11-26. Simon, A., 1992, Energy, time, and channel evolution in catastrophically disturbed fluvial systems. Geomorphology, v. 5. pp. 345-372. Simon, A. and Darby, S.E., 1997, Process-form interactions in unstable sand-bed river channels: A numerical modeling approach. Geomorphology, v. 21. pp. 85-106. Simon, A. and Rinaldi, M., 2006, Disturbance, stream incision, and channel evolution: the roles of excess transport capacity and boundary materials in controlling channel response. Geomorphology, v. 79. pp. 361-383. Spedding, N., 1997, On growth and form in geomorphology. Earth surface processes and landforms, v. 22. pp. 261-265. Starkel, L., 1999, Space and time scales in geomorphology. In: M. Crozier and R. Mausbacher (editors), Magnitude and frequency in Geomorphology. Proceedings of the 4th Intl. Conference on Geomorphology, Bologna. Zeitschrift fur Geomorphologie, Supplementband 115. pp. 19-33. Thomas, M.F., 1999, Evidence for high energy landforming events on the central African plateau: eastern province, Zambia. Zeitschrift fur Geomorphologie, v. 43, n. 3. pp. 273297. Thorne, C.R. and Lewin, J., 1979, Bank processes, bed material movement and planform development in a meandering river. In: D.D. Rhodes and G.P. Williams (editors), Adjustments of the Fluvial System. Kendall/Hunt Publ. Co. pp. 117-137. Torizzo, M. and Pitlick, J., 2004, Magnitude-frequency of bed load transport in mountains streams in Colorado. Journal of Hydrology, v. 290. pp. 137-151. Trustrum, N.A., Gomez, B., Page, M.J., Reid, L.M., and Hicks, D.M., 1999, Sediment production, storage and output: The relative role of large magnitude events in steepland catchments. In: M. Crozier and R. Mausbacher (editors), Magnitude and frequency in Geomorphology. Proceedings of the 4th Intl. Conference on Geomorphology, Bologna. Zeitschrift fur Geomorphologie, Supplementband 115. pp. 71-86.

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Jordan A. Clayton

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White, P.S. and Pickett, S.T.A., 1985, Natural disturbance and patch dynamics: An introduction. In: S.T.A. Pickett and P.S. White (editors), The Ecology of natural disturbance and patch dynamics. Academic Press, Inc. pp. 3-13. Whitlock, C., 1999, Holocene fire-climate-vegetation linkages based on lake-sediment records from the northwestern U.S. Geological Society of America, Abstracts with Programs, v. 31, n. 7. pp. A313. Wilson, R.C., 1997, Broad-scale climatic influences on rainfall thresholds for debris flows: Adapting thresholds for northern California to southern California. In: R.A. Larson and J.E. Slosson (editors), Storm-Induced Geologic Hazards: Case histories from the 19921993 winter in southern California and Arizona. Geological Society of America, Reviews in Engineering Geology, v. XI. pp. 71-80. Wohl, E., 2006, Human impacts to mountain streams. Geomorphology, v. 79. pp. 217-248. Wolman, M.G., 1988, Magnitude and frequency of geomorphic events: matching geography, process and form. Eos Transactions, v. 69, n. 16. pp. 347. Wolman, M.G. and Gerson, R., 1978, Relative scales of time and effectiveness of climate in watershed geomorphology. Earth Surface Processes, v. 3. pp. 189-208. Wolman, M.G. and Miller, J.P., 1960, Magnitude and frequency of forces in geomorphic processes. Journal of Geology, v. 68. pp. 54-74. Yu, B. and Wolman, M.G., 1987, Some dynamic aspects of river geometry. Water Resources Research, v. 23, n. 3. pp. 501-509.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

In: Geomorphology and Plate Tectonics Editors: D. M. Ferrari, A. R. Guiseppi

ISBN: 978-1-60741-003-4 © 2009 Nova Science Publishers, Inc.

Chapter 6

EROSION AND SEDIMENT YIELD ESTIMATED BY GEOWEPP FOR CHECK DAM WATERSHEDS IN EPHEMERAL GULLIES (SOUTH-EAST SPAIN) R. García-Lorenzo1 and C. Conesa-García2,* 1

Environmental Integration and Information Service, Autonomous Community of Murcia Region, Murcia, Spain 2 Department of Geography, Laboratory of Geomorphology, University of Murcia, Murcia, Spain

ABSTRACT

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The WEPP predictive erosion model has been validated for check dam watersheds in Mediterranean ephemeral gullies, in particular for two catchments with semiarid environments representative of the South-East of Spain. By means of its geospatial interface GeoWEPP, implemented around ArcView, rates of soil loss and sediment yield were obtained which were compared to the values for volume and mass of the sedimentary wedges of the check dams. Detailed information as to slope processes compiled in these subcatchments, as well as the geometry of the wedges and the physical characteristics of the material retained by the check dams have allowed the quality of the theoretical estimations of this model to be determined. The GeoWEPP simulation was carried out for isolated rainfall events using the Watershed and Flowpath methods from data as to the environmental conditions of each catchment (climate, soil erodibility, slope, percentage of plant cover, age of the reafforestation pines, etc.) and of the channels (texture, roughness, etc.). The real time of check dam fill is contrasted with the estimated sedimentation period (ESP), establishing the fit between both variables. Finally, the mean lifespan of the dam receptacle and the mean number of events causing filling is indicated, bearing in mind the rhythm of liberation and sediment transfer (solid discharge transferred to the channel -TQs-, final sediment transference coefficient - FST- ) and the age of the structures.

*

Correspondence to: [email protected]

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R. García-Lorenzo and C. Conesa-García

Keywords: Check dams, GeoWEPP, ephemeral gullies, soil losses, sediment yield, SouthEast Spain.

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BACKGROUND The most effective form of erosion control in physical and economical terms is prevention, because once erosion processes accelerate, corrective action is not only expensive, but often also insufficient. To control erosion is very important in order to find a balance between the forces which precede the entrainment of material and those which set up resistance to it. Analysing that balance and the processes which are involved in it is a task which must be done before evaluation and taking steps to control erosion. However, effective erosion control may often be considered more a political problem than a technical one. The expansion and concentration of the Mediterranean agricultural area, for example, led to a drastic change in land use, as well as in water and sediment flow within the environmental systems. Catastrophic events on the Mediterranean fringe of Spain such as those caused by flooding in 1879, 1948 and 1973 in the South East of the country or those of 1957 and 1982 in the Levante region led to excessive loss of fertile agricultural land and increased the degree of concern as to the environmental and economical impact of erosion on local, regional and national scales. In different parts of the world much flooding of unusual magnitude with a high erosion capacity has been suffered over the last century (e.g. in the Dust Bowl in the 1930’s and on the Mississippi in 1993), so that today the problem of erosion resulting from phenomena of this type and its economic and social effects have taken on a very important global dimension. In reply to erosion-related threats, above all on agricultural land, different groups and political organizations have developed and applied techniques to support the agents which are responsible in the different countries for the management of natural resources and the fight against erosion (Troeh et al., 1999). The best-known and most widely applied methods to estimate long-term annual soil loss are the Universal Soil Loss Equation (USLE) (Wischmeier and Smith, 1978) and the Revised Universal Soil Loss Equation (RUSLE) (Renard et al., 1997). Both are simple empirical equations based on factors which represent the main processes causing erosion. USLE and RUSLE have proved to be practical and accessible prediction instruments, up to the point where they have even been incorporated into USA legislation on water and soil conservation. However, these models have been used and at times extensively badly applied to very varied scales in the whole world (Wischmeier, 1976) and it would be desirable to implement a model based on process analysis. Several researchers have underlined the importance of erosion in gully areas when computing total soil loss in the Western European area (Evans and Cook, 1987, De Ploey, 1990, Poesen and Govers, 1990, Papy and Douyer, 1991, Poesen and Hooke, 2001). For the Mediterranean, Poesen et al. (1996) showed that erosion in gullies is by far the most important source of sediment yield in the upper lands of catchments and watersheds areas. In spite of the importance of this type of erosion, only a few physically-based models have been developed to predict soil loss originating in gullying (e.g. CREAMS, WEPP, EGEM). There are others which are very frequently used, such as USLE, RUSLE, SOILOSS or EPIC, which allow soil erosion rates to be calculated examining land use and management techniques,

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Erosion and Sediment Yield Estimated by GeoWEPP for Check Dam Watersheds 119 among other variables as to rainfall and topography. However, none of these is a suitable model to evaluate water erosion in gully areas, and in some cases, such as RUSLE, the erosion rates obtained for mountainous areas are even lower than those estimated with methods which base prediction on discrete analysis of rainfall events (Weltz et al., 1987, Renard and Simanton, 1990, Benkobi et al., 1993). CREAMS (Knisel, 1980) simulates erosion in ephemeral gullies using a procedure which takes into account detachment of soil caused by runoff shear stress, sediment transport capacity and the changing channel geometry, subject to variations in flow regime. The equations which describe the changes in hydraulic geometry in open channels were formulated by Foster and Lane (1983). The process is rather lengthy and needs to be applied several times when calculation is done using CREAMS. To avoid this, some models such as EGE (Ephemeral Gully Erosion Estimator) and EGEM (Ephemeral Gully Erosion Model) have incorporated into their development non-linear regression equations between the values estimated by Foster and Lane’s model (1983) and the implied variables. With the application of the “Ephemeral Gully Erosion” model (EGEM) to data collected for 86 gullies scattered over the South East of Spain (Guadalentín) and the South East of Portugal (Alentejo) (Nachtergaele et al., 1999) a good relationship has been achieved between the theoretical and real gullying volumes (R2 = 0,88). However, a large number of tests must still carried out and the calibration of the model should be continued, as the resulting correlations between the cross sections of the gullied channels estimated and measured are not significant enough, and so it may be concluded, according to the authors’ own words, that EGEM is not at present a model able to predict erosion in ephemeral gullies, at least not in the Mediterranean areas mentioned. In contrast with these empirical models, process research efforts in the USA have led to the development of a soil erosion model based on slope processes (WEPP) (Flanagan and Nearing, 1995). WEPP simulates the climatic and infiltration conditions, water balance, plant growth and residue mulch, ploughing and consolidation to predict surface runoff, soil loss, sediment liberation and deposition over a range of time scales which include storm events, monthly and yearly totals, or a mean annual value based on data for several decades. Comparing the working of WEPP with other recent erosion models which use similar types of data showed that the information quality is very important and that the models based mainly on process analysis which do not require calibration have a great advantage with respect to those needing calibration (Favis-Mortlock et al., 1996). The WEPP model has proved to be a good erosion prediction tool for agricultural and seminatural areas (Povilaitis et al., 1995, Elliot et al., 1991). Elliot et al. (1996) carried out a WEPP evaluation within an afforested slope area and found that this model only predicted half of the runoff observed and ten times more sediment than what was actually produced. Revising the WEPP results under forestry conditions has made it necessary to develop a modified version of WEPP specially for this type of soil. Wu et al. (2000) found that that model overestimated deep percolation of water into the soil and undervalued lateral subsurface flow in the conditions mentioned, producing very low runoff and sediment rates in the simulations with woodland. The modified WEPP for forest soils allows a saturated hydraulic conductivity value to be assigned to the rocky substrate (Ksat), which limits water loss towards deep percolation and increases the subsurface lateral flow. It also adds the subsurface lateral flow values to the surface flow in order to obtain the total runoff volume. Both changes give a more realistic prediction for soils developed under forest formations. The

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R. García-Lorenzo and C. Conesa-García

preliminary validation of the WEPP modified by Wu at al. (2000) for forest land showed that with this rectification, the runoff and sediment yield results for the model seem to represent forestry hydrological processes in a more realistic way than with the original WEPP algorhythms. Elliot and Foltz (2001) later validated the FSWEPP interfaces which use empirical erosion data published in erosion studies for afforested areas, obtaining an acceptable margin of error (confidence limits of 90 %). Koopman (2002), in the GeoWEPP validation study in six small slope areas affected by fires, showed that this model, applied to a DEM of 30 m/pixel, undervalued sediment yield and over-dimensioned runoff volume. Pudasaini et al. (2004) evaluated the efficiency of WEPP when predicting soil erosion from rainfall events for isolated storms in built-up areas in Gosford, New South Wales (Australia), obtaining a degree of efficiency of between 72 and 90 %. According to Weltz et al. (1998), the WEPP model provides a certain guarantee in predicting runoff volume and peak flow (Stone et al., 1992, Tiscareno-Lopez, 1994, Kidwell, 1994), and, on the contrary, less consistent sediment yield estimates (Weltz et al., 1997, Mokhothu, 1996). Such considerations, together with the greater effectiveness of the WEPP model for smaller catchments, make it specially applicable to the drainage areas of the series of check dams which characterize many of the corrected gully ephemeral systems in Mediterranean environments.

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STUDY AREA The catchments of the Torrecilla and Cárcavo ramblas are found in the Southeast of Spain and have a semi arid climate with a tendency to aridification (mean annual precipitation lower than 275 mm, with heavy rainfalls occurring especially in the autumn and at the end of the summer. Both are catchments with torrential hydraulic conditions in which the relief, lithologic components and land uses establish their main differences (López Bermúdez et al., 1998). The Torrecilla catchment has an area of 15.5 km2 and is situated in the southeast of the Region of Murcia (Figure 1), within the interior domain of the Betic Cordilleras. A dense network of drainage has been developed on metamorphic materials (slates, phy-llites, schists and quartzites), with rounded interfluves and scantily deepened channels. The high degree of bifurcation of this network, the erodibility of the schist and shale terrains and the high mean slope gradient of the basin (32 %) gives it a strong erosive potential. The Cárcavo catchment (34.9 km2) is basically a depression composed of marls surrounded by limestone ridges to the north, east and west, with chalk outcrops to the south. Relief to the east and west rises to particularly steep heights of 750-900 m. The Cárcavo rambla drains into the reservoir of the same name, connected directly to the river Segura, the main river system of the South-east of Spain. The result is relief deeply dissected by linear scouring with poorly developed soils reflecting noticeably the lithologic conditions (calcic lithosols on the limestone ranges, calcic Xerosols on the colluvium, marly Regosols on the marls and gypsic Xerosols on the Keuper areas (Castillo et al., 2002).

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Erosion and Sediment Yield Estimated by GeoWEPP for Check Dam Watersheds 121

Figure 1. Location of the selected reaches in the Torrecilla and Cárcavo catchments. Triangular symbols represent the location of the check dams.

To combat this erosion in both areas, in 1972 the “Dirección General de Montes, Caza y Pesca” of the Ministry of Agriculture passed, with revision in 1976, a hydrological-forestry restoration scheme which included the reaforestation of 2579 ha (1342 ha in the Cárcavo and 1237 ha in Torrecilla) with pines (Pinus halepensis) and the building of 73 check dams (40 dams in the Cárcavo catchment and 33 in Torrecilla).

METHODOLOGY In this study the WEPP model is applied, integrated into a spatial interface (GeoWEPP) which allows soil loss rates and sediment liberation to be interpolated for the total surface of

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122

R. García-Lorenzo and C. Conesa-García

each subcatchment and hillslope. GeoWEPP combines the Water Erosion Prediction Project (WEPP) (Flanagan et al., 1995) with the Topography Parameterization software (TOPAZ) (Garbrecht and Martz, 1997, 2000) within the GIS ArcView 3.2 program (Renschler et al.., 2002) and recently GRASS (Hofierka et al., 2002) to model erosion on a hillslope and drainage area scale. To evaluate, particularly, erosion and sediment yield in the drainage areas of the check dams chosen two methods implemented in this graphic interface were adopted: Watershed and Flowpath. These methods were specially designed for use in small sized catchments in combination with Geographical Information Systems (GIS) and Digital Elevation Models (DEM) (Renschler and Lee, 2003). The “Watershed method” is an automated module of GeoWEPP used in the extraction of hillslopes and channels from DEMs. Each watershed area is represented as a rectangle with a characteristic slope profile which drains towards a single thalweg. This mo-dule allows the relatively swift simulation of sediment yield for representative hillslopes within each subcatchment. The “Flowpath method” works by applying the WEPP system to all the possible flow paths within the drainage areas generated from a DEM. However, this method does not at present have any cross-channel circulation component, which limits its use to the prediction of spatially variable erosion rates on hillslopes within or from drainage areas whose channels do not present a large imbalance in the sedimentation-erosion relationship. This method needs a longer processing time and allows soil loss to be simulated along all the possible flow paths within each catchment, but without propagation in the channel (Cochrane and Flanagan, 1999, Flanagan et al., 2000). These methods have been adapted and evaluated in six drainage areas of check dams within the torrential catchments which make up the present study. Three of them belong to the Cárcavo catchment (C33, C10 and C7) and the other three to the Torrecilla rambla catchment (T8, Cc14 and N20). The areas selected in the Cárcavo catchment drain into check dams situated in the headwaters (C33), middle reach (C10) and lower reach (C7). The Torrecilla areas represent headwater sectors (T8), the transition between these and the middle reach (Cc14), and the middle reach, which has less slope and a considerable area of farm land. The criteria used in both cases was to select as final control points the check dams situated on the headwaters, free from additional influence from other precedent check dams (e.g. dams C33 and T8), or those check dams whose area of sediment affluence is clearly limited, either in a natural way or by means of check dams with active retention upstream (C10, C7, Cc14 and N20). The capacity of these methods to predict sediment yield and surface runoff was also analysed, comparing the results with estimates and measurements carried out in the field. In particular, the soil loss and sediment liberation data determined with GeoWEPP for each one of these areas was contrasted with the volumes of material retained by their corresponding check dams.

Simulation with the WEPP Model The WEPP (Water Erosion Prediction Project) is a model based on continuous simulation processes, applicable to small watershed areas and hillslope profiles in order to evaluate different management and conservation options for soil and water based on their different soil

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Erosion and Sediment Yield Estimated by GeoWEPP for Check Dam Watersheds 123

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uses (Ascough II et al., 1997). Together with the improvements to the WEPP windows interface, new additional modules have been incorporated which allow WEPP simulations based on the use of digital information sources to be used by linking them up to Geographical Information Systems (GIS). The Geo-spatial interface for WEPP (GeoWEPP) uses geo-referenced digital information sources such as digital elevation models (DEM) and topographical maps in order to obtain and prepare valid input parameters, in accordance with the soil uses and types for small catchments. The system can be simplified assigning a single use and soil texture to each subcatchment within the drainage area analysed. The integration of orthophotomaps, soil property data, soil use maps, climatic information as well as precise data as to the environmental conditions of these subcatchments is at present being tried out in GeoWEPP with GIS of different structure and format. For this study the WEPP model (Version 2004.700), WEPP Windows interface (April 2005), CLIGEN climatic series generators (versions 4.3 and 5.2) and the GeoWEPP interface have been used. ArcView was chosen as the Geographical Information System for its versatility and ease when using the digital data. The WEPP model represents a new generation of technology for erosion prediction based on the fundamentals of stochastic meteorology data generation, infiltration theories, hydrology, hydraulics, soil physics, plant cover behaviour and erosion mechanism (Flanagan et al., 1995). WEPP uses the sediment continuity equation in a stable regime to estimate erosion and sedimentation on hillslopes and drainage areas based on hourly, daily, monthly or yearly readings, from one or several storm events and under different practices and soil uses. Erosion in slope sectors is represented as two components in the WEPP model: the portion of soil particles detached by rain and carried by a fine laminar flow, known as interrill erosion component, and the portion of soil particles mobilized by shear stress and carried by a concentrated runoff, known as rill erosion component. The sediment continuity equation in a stable regime used to estimate the net detachment of particles from the hillslopes is expressed as (Foster et al., 1995):

dG = D f + Di dx

(1)

where G = sediment load (kg·m-2·s-1) at distance x from the hillslope, x = distance dowstream (m), Di = interrill sediment liberation rate (kg·m-2·s-1) and Dƒ = rill erosion rate (kg·m-2·s-1). The interrill erosion function of the above equation is given by Foster et al. (1995):

⎛R ⎞ Di = K iadj I e σ ir SDRRR Fnozzle ⎜ s ⎟ ⎝w⎠

(2)

where Kiadj = adjusted interrill erodibility (kg·m-2·s-1), Ie = effective rainfall intensity (mm/h), σir = interrill runoff rate (mm/h), SDRRR = interrill sediment liberation rate, Fnozzle = adjustment factor in the impact energy variations for the watering jets, Rs = interrill spacing (m), w = rill width (m) and Dƒ = erosion function in rills, whose expression is:

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

R. García-Lorenzo and C. Conesa-García

124

⎛ R ⎞ D f = K radj (τ f − τ cadj ) ⎜1 − s ⎟ w⎠ ⎝

(3)

Where Kradj = adjusted soil erodibility parameter (kg·m-2·s-1), τƒ = flow shear stress (kg/m/s2), τcadj = adjusted critical rill surface stress (kg/m/s2) y Ct = flow transport capacity concentrated in rillls (kg·m-2·s-1), estimated according to the formula (Foster et al., 1995; Huang and Bradford, 1993).

Ct = K tr q w S

(4)

in which Ktr = constant parameter, qw = unit width flow (m2/s), and S = longitudinal slope (%). The deposition equation is given by Foster and Meyer (1972) in these terms:

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dG β r V f = (C t − G ) + D i dx qw

(5)

Vƒ = effective sediment fall velocity (m/s) and βr = raindrop turbulence coefficient (0-1). The parameters for equations 1 and 5 are normalized with the values of the parameters corresponding to the uniform slope condition. These equations are then solved to estimate soil erosion and deposition at a certain point of interest at distance x from the top of the hillslope in the required time interval. WEPP software consists of an erosion prediction model written in FORTRAN programming language, a climate data generator program (CLIGEN) also developed with FORTRAN (USDA and NSERL, 2006), and a Windows interface (WEPPWIN) designed in C Visual ++ language (Flanagan and Frankenberger, 2002). The interface has access to data bases, organizes the WEPP and CLIGEN simulations, creates all the input files necessary for WEPP and CLIGEN, and carries out the FORTRAN language mo-dels.

Input Data Input data as to climate, soil erodibility, slope and vegetation cover, as well as output data for subcatchments have been measured or estimated for each of the six drainage areas for selected check dams. These entry data were compiled from the input files needed to apply models based on WEPP (Flanagan and Nearing, 1995).

Input Climatic Variables GeoWEPP allows data corresponding to a very large number of stations to be downloaded from Web pages linked to NOAA and to USDA. For the areas under study the stations at Alcantarilla (Torrecilla) and Murcia-Guadalupe (Cárcavo) were chosen, and from these new files in WEPP program were generated. Also the thermo-pluviometrical variation registers available for Cieza and Lorca were used, as these were the nearest stations to the

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Erosion and Sediment Yield Estimated by GeoWEPP for Check Dam Watersheds 125 study catchments which have the longest series (> 50 years). In all cases daily values were used, as the WEPP model structure requires. All the climate data are collected in one climate file. This consists of a theoretical series for 100 years generated from real data for each of the stations considered, among which there are maximum and minimum temperature, relative humidity, rainfall, solar radiation and wind speed records. Adjustment for the orographic characteristics of these areas was made with the PRISM (Parameter elevation Regressions on Independent Slopes Model) model (Elliot and Hall, 2000).

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Topographical Variables (Slope) The drainage areas, subcatchments and channels were obtained by applying TOPAZ to DEMS of 5 m of resolution per pixel generated from digital topographical maps of a scale of 1/5000. The drainage areas of the selected check dams and their corresponding subcatchments were defined according to figures 122 and 123. The limits of the areas practically coincide with those established by means of GRASS, which proves a good adjustment for TOPAZ, as has already been seen on many occasions (Ashley, 2003). Edaphic Entry Variables Physical-chemical soil characterization for the two catchments was carried out using the LUCDEME soil project maps (1/50,000) and sample analysis at the Geomorphology and Edaphology laboratories of the University of Murcia (Tables 1 and 2). The RECONDES project report (2005) also gives information on soil and vegetation cover for the Cárcavo catchment which comes under the “soils” and “management” files needed for GeoWEPP. Rill and interrill erodibility are calculated by the model using as a base for analysis the soil type structure and texture (loamy and loamy-clay in the Cárcavo catchment; sandy and silt-sandy in the Torrecilla rambla catchment). Hydraulic conductivity is obtained using the GreenAmpt effective hydraulic conductivity equation implemented in the WEPP program from data as to rainfall amounts, surface cover and runoff (Albers et al., 1995, Robichaud, 1996, 2000). The parameters considered critical by the model for soil characterization are hydraulic conductivity, rill erodibility and interrill erodibility (Laflen et al., 1997). The values for these parameters were calculated by WEPP from the soil texture and structure data for the Cárcavo and Torrecilla catchments. Table 1. Surface distribution of soil types in the Cárcavo catchment

Check dam C7 C10 C33

Litosols, xerosols

Regosols

Regosols, xerosols

Solonchak

Calcic Xerosols

Gypsic Xerosols

Calcic Fluvisols

ha

%

ha

%

ha

%

ha

%

ha

%

ha

%

ha

%

79.4 13.7 106.2

15.8 3.1 86.8

152.6 235.3 15.3

30.3 53.3 12.5

227.7 111.8 ---

45.2 25.3 ---

--43 ---

--9.7 ---

44.3 --0.9

8.8 --0.7

--0.6 ---

--0.1 ---

--37.1 ---

--8.4 ---

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

R. García-Lorenzo and C. Conesa-García

126

Table 2. Surface distribution of soil types in the Torrecilla catchment. Litosoles, regosoles ha % 17,2 38,6 133,0 100,0 188,7 100,0

Litosoles, xerosoles ha % 27,4 61,4 ---------

Variables Related to Land Uses The files of this type (management files) contain information on vegetation cover quantity and mortality or survival indicators throughout the simulation period. For each subcatchment, within the drainage areas of the selected check dams, a land-use file was constructed based on land-use maps for 1987 and 2005, the first from aerial photos from the CARM (Comunidad Autonoma de la Region de Murcia) (scale 1:18,000) and the 2005 map based on Quickbird images (resolution: 0.7 m/pixel) and field reconnaissance campaigns with GPS (Table 3). 1985 was chosen as a reference date for characterizing land uses figuring in the erosion calculations for the Cárcavo and Torrecilla catchments because it represents use conditions which were quite frequent during the mean check dam fill period (1970-1995). The land uses chosen from the WEPP management window are the predominant ones for each subcatchment and drainage area: for example, afforested with clearings and scrub combined with loamy-sandy soil under 20-year-old pines in the check dam T8 wathershed area (Torrecilla rambla headwaters). For the areas of check dams Cc14 (upper Cocón reach) and N20 (Navazo middle reach) uses with scrub and high grasses (with esparto grass simulation) on silt-sandy soils. After placing the input variables into the program it is possible to modify the channel characteristics according to Strahler’s order (e.g. bed width and type). An additional subroutine gives an option of changing the soil types and land uses for the subcatchments which have been defined by clicking on the area in question on the map visualized with ArcView. Finally, still within the options of the “Management and Soils” module, the width and particle size characteristics of the channel should be introduced. Table 3. Surface distribution of land uses in the Cárcavo and Torrecilla rambla catchments.*

Check dam

Dense afforested

Sparse afforested

ha

%

ha

%

ha

%

ha

%

Scrub

Dry tree

Dry grasses ha

%

Total ha

Torrecilla

Stream

T8 Cc14 N20

--3.5 1.3

--2.6 0.7

36.9 19.9 16.8

82.7 15.0 8.9

7.7 108.8 151.0

17.3 81.8 80.0

----19.6

--0.6 10.4

-------

-------

44.6 133.0 188.7

Cárcavo

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Check dam T8 Cc14 N20

C7 C10 C33

205.0 19.0 58.4

40.7 4.3 47.7

145.6 92.9 21.2

28.9 21.0 17.3

105.1 24.3 31.0

20.1 5.5 25.3

44.9 118.2 ---

8.9 26.8 ---

3.4 187.1 11.8

0.7 42.4 9.6

504.0 441.5 122.4

* Soil uses extracted from Quickbird images (resolution of 0.7 m per píxel).

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Erosion and Sediment Yield Estimated by GeoWEPP for Check Dam Watersheds 127

Output Variables for the Drainage Areas Sediment yield in check dam drainage areas was measured in the field by volumetric calculation of materials retained by each of them. The fill thickness at each point of the sedimentary wedge was calculated from the elevation values of tridimensional images generated with the original and present bed surfaces. The total sediment mass retained in each check dam is found multiplying its density by the volume which it takes up in its receptacle and the material porosity. This more or less realistic approximation allows the degree of fitness for the estimates proceeding from the GeoWEPP simulation to be determined. As to runoff values arising from the model, it is practically impossible to validate them with real data, because of the infrequent hydrological events taking place during the period observed (2000 - 2005).

RESULTS AND DISCUSSION

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The check dams chosen for the simulation (T8, Cc14 and N20 in the Torrecilla rambla catchment; C33, C10 and C7 for the Cárcavo catchment) are situated in drainage areas representative of the main reaches of each stream. The first GeoWEPP result applied to these catchments is the generation of their drainage networks and the outlines of the subcatchments for the chosen check dams (figures 2 and 3). The chosen areas for the Torrecilla catchment belong to the headwaters (T8), middleupper reach (Cc14) and middle (N20). The lower reach, in this case, was not included in the trial because it was difficult to compare the model results with the sediment volumes retained by the check dams on this reach as they were only built recently and have not been filled to any appreciable extent.

8 14

N N 20

Check dams Check

0

1 km

Figure 2. Drainage network and subcatchment areas for the chosen check dams obtained with TOPAZ. Torrecilla rambla catchment.

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128

R. García-Lorenzo and C. Conesa-García

7

10

33

N

Check dams Check dams

0

1 km

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Figure 3. Drainage network and subcatchment areas for the chosen check dams obtained with TOPAZ. Cárcavo rambla catchment.

On the other hand, in the Cárcavo catchment the three main reaches are represented: headwaters (C33), middle reach (C10) and lower reach (C7). The selection criteria were that the check dams chosen had their own sediment supply areas, not only natural (first headwater dam) but artificial (check dams preceded by others which have not yet been filled and which have a high retention capacity). The WEPP model creates many possibilities for its components, including climate simulation, subsurface hydrology, water balance, vegetation growth, residue mulch, land use, laminar runoff, hillslope erosion, fluvial hydraulics and eroded channel surface. The usual environment only allows a small part of the WEPP model outputs (runoff, soil loss, deposit and sediment yield from hillslopes and channel segments) to be visualized. The mean yearly simulation results obtained from the WEPP Watershed method are shown in a sediment yield map. Since surprisingly ArcView 3.2 does not allow negative values to be represented on raster maps, the evaluation results are mapped as a measurement relative to a tolerable or type value (T) soil loss. The concept of value T (Schertz, 1983) in theory describes the annual replacement rate of a soil type in order to maintain sustainable land use. The Natural

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Erosion and Sediment Yield Estimated by GeoWEPP for Check Dam Watersheds 129 Resource Conservation Service (NRCS) implemented T for many places in function of the properties of the roots which limit the subsurface soil layers, the climate characteristics of each region and the economic potential of the land and natural resources. The values of T found in this way are normally around 11.2 t ha-1 year-1. The soil loss and sediment yield results are classified in relation to value T (figure 124), taking as a criteria T = 10 t ha-1 year-1. This value seems to be more suitable, in accordance with climate conditions, soils and the roots systems of the area’s plants, the latter having been studied in detail in the RECONDES project (2005). Tolerable rates, found below the T threshold, are shown in green, intolerable ones in red and deposition areas in yellow (figure 4). As well as raster possibilities, GeoWEPP generates text files which give information on mean annual rainfall, number of storms, total runoff, soil loss and sediment yield for the subcatchments and, in our case, for the check dam drainage areas. Sediment yield

Soil loss

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0

0

200 Metres m Metres

500 Metres m

N N

Sedimentation

0

500 Metres m

Erosion

Figure 4. Sediment yield and soil loss rates estimated with GeoWEPP for the drainage areas at check dams T8 (Torrecilla rambla), Cc14 (Cocón rambla) and N20 (Navazo rambla). Torrecilla catchment.

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130

R. García-Lorenzo and C. Conesa-García

The Watershed Method results are mapped as sediment yield rates for each representative hillslope simulated in relation to a segment of the channel. As it can be seen from figures 4 and 5, sediment yield varies from 0 to 20 t ha-1 year-1 in the drainage areas of the chosen check dams for the Torrecilla catchment and between 0 and 70 t ha-1 year-1 in those of the Cárcavo catchment check dams. Within the Torrecilla catchment, the headwater areas represent the most important source of sediments, with rates of 10 to 20 t ha-1 year-1 over more than 55 % of its surface. And even so, the distribution of the sediment yielding sectors in some of the headwater subcatchments, such as dam Cc14 (upper part of the Cocón rambla) is asymmetrical, with the places where most erosion and detachment of materials occurs being concentrated on one of the watersheds, the left one in this case. As to the check dams situated in the Navazo subcatchment, these are still at the fill stage, because the hillslopes are more stable and the sediment yield rates are lower, generally below 0.75T (that is to say, F

F P

if P≤F (2)

where P is the rainfall rate and F the infiltration capacity. In this simulation we neglect the soil moisture and the upward flux from the water table. Since groundwater discharge occurs when the water table rises higher than river bed level, water table elevation h calculated with the eq. 1 is compared to land surface elevation z. The volume of groundwater discharge Qg is determined from the conservation of mass:

Qg =

{

ΔAϕ (h − z ) 0

if h>z if h≤z

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

(3)

S. Pelacani, M. Märker and G. Rodolfi

152

where ΔA is the grid cell area and φ is the effective porosity. The contribution of Horton runoff to the discharge was calculated as a function of the contributing area A while the contribution of Dunne runoff was calculated considering the water table to be parallel to the soil surface (kinematic assumption) and soil transmissivity (Ambroise et al., 1996). To produce realistic hydrological pattern of the study basin one has to take into account the areas affected by trampling (Pelacani et al). The pathways can, in fact, condition the overland flow and hence determine the direction of the gullies.

Model Calibration The study area is Mhalambanjoni river basin, a right tributary of the Mbuluzi river, located 20 km North of Manzini, Swaziland (Figure 1). The catchment area is situated in the Upper Middleveld on communal grazing land. It has a surface of ca. 42 km2 with an elevation that ranges from 610-760 m a.s.l. and with average slope of 12%. It is an ungauged basin. The data from the rain gauges and the hydrograph stations for the Mbuluzi river are presented in table 1 and table 2 respectively. Annual precipitation is approximately 910 mm (Manzini station) while the mean annual discharge range from 379 Mm3 (GS20) to 30 Mm3 (GS10). The Mhalambanjoni river catchment has been modelled previously for the annual maximum runoff depths starting from the consideration that a flow depth D is related to flow discharge Q and hence it can be calculated through the formula: D=0.48Q0.45 (Sidorchuk, 1999; Sidorchuk et al., 2003). A shallow unconfined aquifer underlies the catchment. Table 1. Rain gauges for the Mbuluzi river, Swaziland Station

Location

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S Manzini Mpisi Mbabane Mpala Homestead

26°28’ 26°20’ 26°12’ 26°05’

Elevation [m a.s.l.]

Mean rainfall

600 394 182 339 262

911 704 1382 657 683

E 31°32’ 31°08’ 31°42’ 31°45’

annual

Table 2. Hydrograph stations and hydrologic statistics for the Mbuluzi river, Swaziland

Station No. GS3 GS4 GS10 GS20

River

Mean Drainage annual Location LAT S LONG E area discharge 2 [km ] [Mm3]

Black Croydon 26°10 Mbuluzi Black Lepper 26°12’ Mbuluzi White Mpisi 26°22’ Mbuluzi White Mbuluzi

Mean daily discharge [m3/sec]

Std of Mean daily discharge

CV of Mean daily discharge

31°35’

723

224

7.2

32.6

4.5

31°11’

64

94

2.2

12.0

5.4

31°31’

86

30

0.7

2.8

4.0

2258

379

15.0

18.0

1.2

-

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Modelling the Potential Impact of Groundwater Dynamics on Gully Erosion

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A biotite granodiorite saprolite is recognized as good aquifer for boreholes development especially along the contacts between the granodiorite and diorite or diabase. These boreholes yield up to 4 L/s (Hydrogeological Map Sheet 12, 1991). Unfortunately, the thickness of the aquifer is not reported. In this report, the aquifer was divided in three main layers: a 2 m layer corresponding to the soil, a 30 m layer of saprolite followed by a poorly fractured rock of unknown thickness. In previous studies the granodiorite saprolite was divided into upper, middle and lower layers (Mushala et al. 1994; Scholten et al. 1997). For these layers the hydrological characteristics are known and reported in Mushala et al. (1994). Based on personal observations and literature (see above) the upper aquifer was set to 2 m, which corresponds to soil and upper saprolite layer. Because the saprolite thickness is highly variable, during the simulations the aquifer thickness range was set from 2 m to 15 m. The saturated hydraulic conductivity Ks was taken from literature (Scholten, 1997), but it was available only for two “soil catena” sites in upper and middle slope positions. For sites with lacking ks values, as a proxy soil texture information (Murdoch, 1968) is linked to hydraulic conductivity (table 3). Local ferricretes present above clay horizons tend to reduce the vertical permeability. The low permeability of clay and the hardpan layers affect ground water flow patterns. Where the saprolitic sand aquifer is confined by hardpan or paleosol, artesian conditions occur. Furthermore wetland areas are associated with the headwater river and gully systems that contribute to maintain base flows during the dry season. In south-central Africa, as reported by Withlow (1989), these wetland areas are recognized in granitic terrain. In the Mbothoma gully area wetlands are responsible to maintain a superficial water table in the 2 m soil thickness (Figure 9). The wetlands are associated with Mineral Hydromorphic sols (I soil set; Murdoch, 1968) characterized by “ill-drainage”, because the vertical flow is prevented by the presence of less permeable layer (presence of stone lines or plaguing layer). In these areas vertical percolation is only possible if soil cracking is occur. Hence, in the study area soils have a significant effect on the runoff generation characteristics.

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Table3. Soil textures and hydraulic conductivities used in the hydrologic model. Soil Set/Soil Series A

Description

Texture

Ks [m/sec]

Note

Ferrallitic Soil

Loam

3.08·10-3

CH

Ferrallitic Soil

Clay

3.08·10-3

I

Mineral Hydromorphic Soil Ferralitic Soil

Clay

0.21·10-3

Imperfect drainage Moderately permeability Ill-drained bottomland

Loam on thick stoneline Loam Sand Clay loam

1.79·10-3

JH M O S/Sh TH

Ferrallitic Soil Lithosol Intergrade to Lithomorphic Vertisol Ferrallitic Soil intergrade to Regosol

Loamy sand to sandy loam

4.25·10-3 1.79·10-3 0.21·10-3

Very permeable Rapid drainage

4.25·10-3

Very permeable

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For Mbothoma area Sidorchuk et al. (2003) applied a gully evolution model based on surface water hydrology characteristics. The present research is also taking into account ground water processes. The hydrologic model was applied at gullied and ungullied area using a 5 m grid resolution. The mean rainfall intensity was obtained from Kiggundu (1986). A 25-year return period was chosen as probability distribution of rainfall intensity. The parameters used in the hydrologic model are reported in table 4. Table 4. Parameters values used in the hydrologic model. Parameter Rainfall intensity , P Rainfall duration Recurrence interval Infiltration capacity, I Hydraulic conductivity, Kh

Value 36.5 mm h-1 30 min 25 years 10.2 – 26.8 mm h-1 0.00021 – 0.00425 m h-

Specific yield, Sy

0.30

Effective porosity, φ

0.43

Notes Kiggundu (1986) Kiggundu (1986) Kiggundu (1986) Mushala (1994) Scholten (1997)

1

coarse sand Morris and Johnson (1967) coarse sand

RESULT

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Model Simulations The hydrologic model was used to simulate the ground water dynamics in the upper Mhlambanyoni basin. The objective was to examine the relationship between gully evolution and basin hydrology when ground water table is varied. A High resolution Digital Terrain Model of ‘60s is used to represent the topographic features that drive the simulated ground water movement. At the start of the simulations, the water table was set to the ground surface, but subsequently adjusted in response to the gully S1 stage (see above Analysis of Digital Elevation Models). The single phases of gully S1 development show an incising processes from 1947 to 1961 with a depth of 5 m. Subsequently, the gully increased principally in depth, in 1971 the gully depth reached 12 m and in 1998 it was 18 m deep. Most of the hydrological parameters are fixed for all the simulations in this study, and their values are reported in table 4. However, some parameters are not known. The specific yield Sy and effective porosity φ are assigned values that are appropriate for coarse sand. For sites with lacking ks values, as a proxy soil texture information were linked to hydraulic conductivity (table 3). Making use of equations 1; 2; 3 and a parameters reported in table 4, a series of simulations were conducted using (i) a value of 0.00425 m h-1 for all soil set and (ii) a value of ks characteristic for each soil set reported in table 3. For simulations with a water table depth between 0 and 15 m and Ks set equal to the Ks of the middle saprolite layer, we found the following results: 1) There is not relationship between contributing area and groundwater discharge;

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Modelling the Potential Impact of Groundwater Dynamics on Gully Erosion

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2) There is a mutual response of the basin to variations in water table level; 3) There is a relationship between groundwater discharge and stages of gully evolution; 4) The contribution of ground water to the stream flow discharge shows the same behaviour where gully occur and where the gully is not present (see S1 and S4 in Figure 10).

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For simulations considering Ks variable, in function of soil information, and for water table depth from 0 to 15 m the same results as in the first simulations were found except for soils with moderately permeability in the footslope position that show a reduction in groundwater discharge. However, this fraction can be responsible for the sapping processes. Figure 10 shows the average relative contributions of Horton runoff, Dunne runoff and groundwater discharge to the stream flow as a function of the water table depth. The shape of the curve and the relative contribution of the runoff and groundwater to the total discharge of the gullies differ in function of topography and the stage of its evolution. Gully S1 shows a maximum contribution of groundwater to the stream flow discharge of up to 50-60 % when water table depth increase to a maximum value of 6 to 8 meters. The shape of this curve is inverse to the Horton and Dunne runoff curves.

Figure 10. Simulation of the groundwater discharge Qg for the 6 study sites in function of water table depth (h-zb). Where h is the water table elevation, and zb is the impervious base.

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S. Pelacani, M. Märker and G. Rodolfi

As the water table depth increases, the relative contribution of Dunne runoff decreases. From a value of 6-8 meters it increases again up to values of 13 m. At this elevation the groundwater discharge and Dunne runoff contribute 25% to the stream flow. For a gully in a stable stage the contribution of the groundwater discharge is lower than that of the Horton and Dunne contributions. Particular attention must be paid at site S4 where presently gullies do not occur. This site is opposite (western flank, see Figure 6) to the gully S1 in dynamic phase, either slopes are affected by cattle path, but in site S4 no gully occurs. The shape of the curve of the groundwater discharge is the same for site S1 and S4, but they differ for the maximum relative contributions. For the Horton and Dunne runoff the value are the same, but in S4 the contribution of saturated excess overland flow is more than in S1.

CONCLUSION

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For this analysis the following main conclusion can be drawn. 1. Using a collection of DEMs it was found that the variation of the Mhalambanjoni longitudinal profile was influenced by the presence of dykes. From field observation and literature information this step corresponds to the presence of the quartzite dyke, more resistant than the the granodiorite. During the late ‘50s the erosional base level of the Mhalambanjoni stream was lowered. It is hypothesized that a Cyclone caused the removal of the blocking dikes. However the longitudinal profile of the right hand side tributary of the Mhalambanjoni stream apparently is not affected by the catastrophic event. 2. From the aerial photos observation it could be noted as the Upper Mhalambanjoni watershed are affected by a severe gully erosion, most of them in a dynamic phase. Conversely, its tributary is affected by few small gullies in a stable phase. Furthermore, the presence of cattle path along this side are not linked to the gully development. 3. The hydrological model applied in this study simulates stream flow generation by infiltration-excess runoff or groundwater discharge and reproduces the main differences observed in the DEMs. Three hydrologic zones can be identified in the basin. One zone corresponds to locations where groundwater discharge represent a maximum contributions to stream flow. The extent of this zone is important for the long term basin evolution because it is directly connected with the base level of the stream. The maximum contribution of groundwater discharge corresponds to groundwater depth values from 6 to 8 m. Particular attention must be paid to sites where presently gullies do not occur. For example site S4 is the opposite to gully S1 in dynamic phase, either slopes are affected by cattle path, but in site S4 no gully occur. In that place the contribution of the groundwater discharge is the same like on site S1, they differ in the maximum relative contribution. The second zone is important for the production of Horton and Dunne runoff as well as groundwater discharge depending on the characteristics of the rainfall event. The result suggests that the topography promotes more groundwater discharge due to Dunne runoff. The

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Modelling the Potential Impact of Groundwater Dynamics on Gully Erosion

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third zones can produce especially Horton runoff. These areas correspond to gullies developed in convex slope or to the stable gullies. 4. The study shows that stratigraphic controls or specific geomorphological processes are important but not yet implemented in the model. Thus, further models development is needed to be able to reproduce the effects of this features and processes in the simulations.

ACKNOWLEDGMENTS We sincerely thank Dr. Fiorenzo C. Ugolini (University of Florence) for his detailed comments that greatly improved this manuscript. The help of Dr. Rosmary Mendler (University of Jena) was invaluable for assisting with Planicomp analyses. We are indebted to Prof. Hezekiele Mushala (University of Swaziland) for his help in the data collection. Part of this work was supported by the European Union, INCO-DC, contract nr. IC18-CT97-0144.

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REFERENCES Ambroise, B.; Beven, K.; Freer, J. Water Resour Res. 1996, 32, 2135-2145. Dardis, F.G.; Beckedahl, H.R. In Geomorphological Studies in Southern Africa; Dardis, G.F.; Moon, B.P.; Ed.; Publisher: Balkema, Rotterdam, NL, 1988; pp 285-296. Dunne, T.; Moore, T.R.; Taylor, C.H. Hydrol Sci Bull. 1975, 20, 305-327. Dupuit, J. Etudes theoriques et pratiques sur le mouvement des eaux dans les cannaux decouverts et a travers les terrains permeables; Second Ed; Publisher: Dunod, Paris, FR, 1863. Egboka, B.C.E.; Nwankwor, G.I. J Afr Earth Sci. 1985, 3, 417-425. Harvey, AM. Geomorphology 1992, 5, 323-344. Horton, R.E. Geol Soc Am Bull. 1945, 56, 275-370. Howard, A.D. Geomorphology. 1995,12, 187-214. Huang, X.; Niemann, D.J. Earth Surf Process Landf. 2006, 31, 1802-1823. Hunting Technical Services. Review of the rural development area programme; Final Report of the Ministry of Agriculture and Cooperatives; Publisher: Mbabane, SW, 1983. Kiggundu, L. Distribution of rainfall erosivity in Swaziland; Research paper 22; University of Swaziland. Publisher: Kwaluzeni, SW, 1986. Kosov, B.F.; Nikol’skaya, I.I.; Zorina, Y.F. In Eksperimental’naya Geomorphologiya; Makkaveev, N.I.; Publisher: Moskva, RUS, 1978; vol. 3, pp 113-140. Laity, J.E.; Malin, M.C. Geol Soc Am Bull. 1985, 96, 203-217. Märker, M.; Moretti, S.; Rodolfi, G. Geogr Fis Dinam Quat. 2001, 24, 189-198. Morgan, R.P.C.; Mngomezulu, D. Catena 2003, 50, 401-414. Morris, D.A; Johnson, A.I. U.S. Geol. Surv. Water Supply Paper 1967, 1839-D, pp. 42 Murdoch, G. Soils and Land Capability in Swaziland; Ministry of Agriculture; Publisher: Mbabane, SW, 1968; pp360.

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S. Pelacani, M. Märker and G. Rodolfi

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Mushala, H.M.; Scholten, T.; Felix-Henningsen, P.; Morgan, R.C.P.; Rickson, R.J. Soil erosion and river sedimentation in Swaziland. Final report to the EU, Contract number TS2-CT90-0324, 1994; pp 138. Pelacani, S. Evolution of gullied landforms in a catchments of Swaziland, Southern Africa, by means of photo interpretation techniques and hydro-erosive models.Unpublished Thesis, University of Florence, 2001, pp. 211. In Italian. Price Williams, D.; Watson, A.; Goudie, A.S. Geogr J. 1982, 148, 50-67. Scholten, T. Soil Technology 1997, 11, 219-228. Scholten, T.; Felix-Henningsen, P.; Schotte, M. Soil Technology 1997, 11, 229-246. Sidorchuk, A. Catena 1999, 37, 401-414. Sidorchuk, A.; Märker, M.; Moretti, S.; Rodolfi, G. Geogr Fis Dinam Quat. 2001, 24, 177187. Sidorchuk, A.; Märker, M.; Moretti, S.; Rodolfi, G. Catena 2003, 50, 507-525. Sidorchuk, A. Catena 2005, 63, 299-317. Whitlow, R. Zambezia 1989, 16, 123-150. WMS Associates. Gully erosion in Swaziland. Final report. Publisher: Fredericton, CDN, 1988.

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In: Geomorphology and Plate Tectonics Editors: D. M. Ferrari, A. R. Guiseppi

ISBN: 978-1-60741-003-4 © 2009 Nova Science Publishers, Inc.

Chapter 8

PALEOMAGNETIC EVIDENCE FOR SIBERIAN PLATE TECTONICS FROM RODINIA THROUGH PANGAEA TO EURASIA D.V. Metelkin*, A.Yu. Kazansky and V.A. Vernikovsky Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia

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ABSTRACT The tectonic history of the Siberian continental plate is discussed here at the main stages of geological chronicle: from Rodinia supercontinent, through Pangea supercontinent, up to present-day position of Siberia within the structure of Eurasia. We start from the end of Mesoproterozoic where the Rodinia supercontinent was assembled. The available geological and paleomagnetic data set suggests that at the MesoNeoproterozoic boundary Siberian craton was a part of Rodinia supercontinent lengthening the Laurentia northward. The reconstruction implies that the southern (in modern coordinates) margin of Siberia was oriented towards the northern margin of Laurentia. Most likely Siberia represented a giant promontory in the southeast of Rodinia, because during the Late Mesoproterozoic and Early Mesozoic, the western, northern and eastern (in modern coordinates) margins of Siberia represented marginal marine basins opened to the ocean. New paleomagnetic data show that the Siberia - Laurentia disintegration during the Neoproterozoic Rodinia break-up has developed progressively from west to east along the southern (in modern coordinates) margin of the Siberian craton under the controlling role of strike-slips. During Neoproterozoic on the background of the Rodinia break-up in the west of the Siberian craton, a gradual transformation of passive continental margin into active continental margin occurred with a development of Late Neoproterozoic island arc systems. All of those processes have determined the further tectonic stile of Siberian craton during the Late Precambrian. The stage of accretion of the Neoproterozoic island arc to the Siberian paleocontinent has been going in pre-Vendian, however, even at the end of Vendian the *

Correspondence to: D.V. Metelkin, Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch, Russian Academy of Sciences, Akad. Koptyug ave., 3, Novosibirsk, 630090, Russia, e-mail: [email protected]

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160

D.V. Metelkin, A.Yu. Kazansky and V.A. Vernikovsky regime of active continental margin was again resumed at least in the southwestern Siberian plate. Vendian to Earliest Paleozoic is the next important step in tectonic history of the Siberian plate. Its connecting to dynamics of development of the island arc system lies along the south to south-western margin of the Siberian continent. Relicts of these island arcs formed the framework of the Caledonian structure of the Central Asia fold belt and appeared on the Altai-Sayan region (southwestern frame of Siberian craton). Geological and paleomagnetic data prove that the modern mosaic structure of this frame is the result of deformation of a primary stretching island arc system during its oblique accretion to the craton under the large-scale strike-slip conditions. Late Paleozoic dynamics of crust deformation of the Siberian plate at the stage of collision with Kazakhstan Baltica and Kara continents was most likely controlled by deep faults inherited from Early Paleozoic structure. At the end of the Paleozoic, strike-slips movements of tectonic domains within the structure of Eurasian continental plate have taken place. This key moment in the tectonic history of Siberia has been manifested by the dramatic trap eruption well known as the Siberian Large Igneous Province. Paleomagnetic evidence obtained for the Mesozoic of Siberia suggest Mesozoic geological history of Eurasia to be essentially determined by the strike-slip motions of large-scale tectonic domains within its structure. The synthesis of paleomagnetic data on the Mesozoic of Eurasia justifies a sinistrial strike-slip motion of the assemblage of Siberian structures relative to the European and North-China ones during the Mesozoic. This process is reflected by the clockwise rotation of the Siberian domain. The discrepancy in paleomagnetic pole positions of deferent domains demonstrate the systematic character and allow to be revealed the scales of strike-slip motions associated with this rotation and to propose a new tectonic model describing the history of the closure of Mongolo-Okhotsk paleoocean.

Keywords: Siberian plate, paleomagnetic data, tectonics, reconstruction, strike slips, Rodinia, Pangaea, Eurasia

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1. INTRODUCTION The modern structure of the Eurasian plate represents an archive of prolonged tectonic history. The main tectonic units of the structure include Baltica and Siberian cratons that were formed in the Paleoproterozoic and “sewed together” by the folded structures from the Neoproterozoic to the Mesozoic age. Those folded structures comprise the Central Asian belt that resulted from the evolution of the Precambrian-Phanerozoic ocean basins and the Siberia - Baltica collision. In general, this territory is known as Northern Asia (Fig. 1). The geological history of the region includes several tectonic stages connected with a gradual growth of continental crust and development of its inner structure. We shall start our tectonic tale of the Siberian plate from the Meso/Neoproterozoic boundary when the main cratons of Northern Asia were a part of Rodinia [Li et al., 2008]. It is suggested that Rodinia was integrated as the result of the Greenville collision 1.0 billon years ago. In traditional models, the Laurentia comprises the core of Rodinia [Hoffman, 1991, Dalziel, 1992]. The cratons of East Gondvana (Australia, Antarctica, India and, possibly, South China) are arranged along the west (here and after in modern coordinates, if not specified) margin of Laurentia. Baltica and Amazoina along with the minor blocks of Africa comprise a tectonic collage on its eastern side [Li et al., 2008].

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Figure 1. Main tectonic units of Nothern Asia (modified from [Berzin et al., 1994]) 1 - main cratons, 2 - Late Proterozoic orogens, 3 - Early Paleozoic folded belts, 4 - Late Paleozoic folded belts, 5 - Late Paleozoic to Mesozoic undivided folded belts, 6 - Mesozoic folded belts, 7 Mesozoic to Cenozoic sedimentary basin of West Siberia overlapping the structure of the Central Asia folded belt

The paleogeographic position of Siberia within the structure of Rodinia is hotly debated (see the review by [Pisarevsky and Natapov, 2003], for example). Ambiguity of debated tectonic models is determined also by a lack of paleomagnetic information. The Neoproterozoic paleomagnetic data set for Siberia is quite poor. Actually, the whole stage of break-up of Rodinia and separation of the Siberian craton is not supported by paleomagnetic data from Siberia. Different authors estimate this period from 800 to 550 Ma [Li et al., 2008]. A many-valued interpretation of paleoposition of Siberia relative to the other continent during the Neoproterozoic and acute shortage of paleomagnetic data prevent the estimation of dynamics of oceanic basins opened or reorganized as the result of disintegration of continental masses of Siberia and Laurentia during the Rodinia break-up. Here we present a synthesis of our recent paleomagnetic evidence justifying the paleogeographical position of Siberia during Neoprotherozic, which are published dominantly in Russian and thus are inaccessible for international scientific community. Our paleotectonic model of the Neoproterozoic stage of the Rodinia break-up, based on the paleomagnetic data implies disintegration of Laurentia and Siberia essentially as the result of strike-slip tectonics [Metelkin et al., 2007a].

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162

D.V. Metelkin, A.Yu. Kazansky and V.A. Vernikovsky

The second hotly debated stage of Siberian tectonic history we are going to discuss is connected with the Late Precambrian - Early Paleozoic active continental margin on the southwestern frame of the Siberian plate. A large island arc system along the southern and southwestern margin of Siberia is reconstructed in many different ways [Sengor et al., 1993, Mossakovsky et al., 1993, Didenko et al., 1994, and others]. Even the kinematics of the Siberian plate is still ambiguous [Metelkin et al., 2005a]. We have created a paleomagnetic data set from the Early Paleozoic island arc terranes of the southwestern margin of the Siberian craton that makes it possible to analyze the lateral movement in the margin of the continental plate test and to estimate kinematics of Siberia during the Early Paleozoic. In particular, paleomagnetic data testify that Neoproterozoic strike-slip motions that are responsible for the evolution of oceanic basins around Siberia have predetermined sufficiently the dynamics of the Paleozoic accretion events. Synthesis of paleomagnetic data suggests that strike-slip motions are precisely the main factor, which is responsible for growth and deformations of the continental crust of Northern Asia during the Paleozoic. Paleomagnetic evidence from Siberian Arctic including fold and trust structures of the Taimyr Peninsula and Severnaya Zemlya archipelago indicates that the strike-slip motions connected with the rotation of the Siberian plate have not only resulted in folded structures in the south and the west of the Siberian plate but also determined the intensive collision in limits of the Siberian Arctic [Metelkin et al., 2005b]. The closing of the Late Precambrian to Early Paleozoic oceans that separated the continental plates of Siberia, Baltica, Kazakhstan superterrane and Kara microcontinent also became a final episode of evolution of the Central Asian folded belt [Sengor, Natalin, 1996]. Siberia among the other continental masses was involved into a composite structure of Eurasian plate and formed the Laurasian part of the Pangaea supercontinent. This key moment in the tectonic history of Siberia has been manifested by the dramatic trap eruption at the Permian/Triassic boundary well known as Siberian Large Igneous Province. The literature on Siberian LIP is quite voluminous [Zolotukhin, Al'mukhamedov, 1988; Dobretsov, 2005 and many others].Our paleomagnetic results come from the most southern outcrop of Siberian traps located in Kuznetsk Basin. Synthesis of geological, paleomagnetic and geochronologic data attests that the Siberian LIP was extruded by a very short period and the intensity of magmatism over the province is directly connected with the geological structure of specific region. We suppose that in the Kuznetsk Basin the trap magmatism is essentially controlled by the strike-slip structures that were formed during the growth of continental crust during the Paleozoic and then reactivated in the Late Paleozoic - Early Mesozoic. The Mesozoic stage is generally known as a time of “stable Asia”. It is suggested, that active tectonic processes in the Northern Asia are concerned with the reorganization of the Eurasian plate structure completed at the beginning of the Mesozoic just after trap magmatic event. However, a number of pieces of geological evidence [Voronov, 1997], and also paleomagnetic data presented here prove the presence of large-scale intraplate strike-slip motions between the main tectonic domains of the Eurasian plate [Metelkin et al., 2008]. The reported list of evidence provide the base to improve our viewpoint on the geodynamics of the Transbaikalia region where the Mesozoic history is connected with closure of the Mongol Okhotsk ocean [Zorin et al., 1999, Kravchinsky et al., 2002a, Metelkin et al., 2007b].

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2. SIBERIA IN RODINIA AND BREAK-UP PROCESS DURING NEOPROTEROZOIC

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2.1. Brief Review The position of Siberia in Rodinia is generally shown as lying along either the northern margin of Laurentia (excluding models proposed by [Sears, Price, 2000]). However, different models show its position in a range of orientation (see review by [Pisarevsky, Natapov, 2003]). Early models [Hoffman, 1991, Dalziel, 1992] supposed that Siberian craton is connected with Lauerntia through its northern margin. Later in model by [Condie, Rosen, 1994] Siberia is rotated and turned to Laurentia with its eastern part. In other models the authors tried to reveal geological and structural relations between Precambrian of northern margin of Laurentia and south margin of Siberia [Frost et al., 1998, Rainbird et al., 1998, Pisarevsky et al., 2008]. Most of these reconstructions are based on some suggested geological piercing between two continents (see review by [Pisarevsky, Natapov, 2003] or [Pisarevsky et al., 2008]). However, one of the modern comprehensive summaries of key paleomagnetic poles from Rodinia is presented by [Li et al., 2008]. Analysis of available paleomagnetic data leads to conclusion that Siberia was oriented towards Laurentia with its southern margin and located some northward, probably at some distance. The space between the cratonic blocks may be occupied by an Early Precambrian “missing link” terrane, for example hypothetic Arctida terrane [Pisarevsky et al., 2008, Li et al., 2008]. Siberian part of this reconstruction is based on the paleomagnetic data covering a comparatively short interval between 950 and 1050 Ma, that roughly corresponds to the final stage of supercontinent assemblage. The period of break-up of the supercontinent (860–570 Ma) until the present time was actually a “white spot” in the paleomagnetic study of Siberia. Due to the lack of plausible paleomagnetic data, the Neoproterozoic interval of Siberian APW path [Smethurst et al, 1998] that is widely using for paleotectonic reconstructions is in fact a pure interpolation between comparatively reliable Phanerozoic APW trend and mentioned above Mesoproterozoic poles for an interval from 950 to 1050 Ma. When constructing this Mesoand Neoproterozoic paleomagnetic pole positions in southern hemisphere that extend Phanerozoic APW path to the east are taken as a normal polarity [Smethurst et al., 1998]. However, today version of Siberia position in Rodinia [Li et al., 2008] follow the reversed polarity for those poles and thus corresponding westward Siberian APW [Metelkin et al., 2005a, 2007a]. Below we briefly summarize our new paleomagnetic results for Neoproterozoic of Siberia which set limits on paleoposition and allow to revise dynamics of Rodinia break-up as well. This paleomagnetic data was obtained in Pre-Sayan and Yenisey Ridge of the southwestern margin of Siberian craton (Fig.2). Within the limits of these areas, we shall discuss the geological features and paleomagnetic results.

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Figure 2 Tectonic scheme of Sayan-Yenisey folded area (modified from [Metelkin et al., 2007a]) 1 - Sharyzshalgay terrane, granulite-gneiss complexes (AR-PP), 2 - Biruysa terrane, granuliteamphibolite complexes (AR?-PP), 3 - Angara-Kan terrane granulite-amphibolite complexes (PP), 4 East-Angara terrane, terrigenious-carbonate deposits of passive cotinental margin (NP), 5 - CentralAngara terrane, (МP?-NP), 6 - predominantly volcanic and volcano-sedimentary series metamorphosed from green-schist to amphybolites (PP) of Tumanshet, Urik-Iya and Onot terranes 7 - Panimba ophiolite belt (MP-NP?), 8 - overlapping predominantly molasses complexes (NP2-3), 9 - predominantly carbonate deposits (NP2-3), 10 - island arc complexes and associated ophiolites (NP2) of Sakovo and Predivinsk island arc terranes, 11 – island arc volcano -sedimentary complexes of East Sayan (NP2?) 12 - overlapping predominantly volcanic and volcano-sedimentary series (D) of Agul troughа, 13 overlapping predominantly sedimentary complexes of Phanerozoic, 14 - granitoids of Tarak and Sayan complexes (PP3), 15 - syn- and post-collissional granitoids of Teya and Erunda complexes (NP1), 16 syn- and post-collissional granitoids of Ayakhta and lushiha complexes (NP2), 17 – main faults. Rectangles indicate locations of paleomagnetic samples 1 – Pre-Sayan trough (Fig.3) 2 – Predivinsk (Fig.6); 3 – Ust-Amgara (Fig.5).

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2.2. Geology and Paleomagnetic Evidence from Pre-Sayan Area The Pre-Sayan area is separated by a large strike-slip fault named Main Sayan fault from the terranes with Neoproterozoic to Paleozoic ophiolites and island arc complexes of the Central Asia folded belt. Archean and Paleoproterozoic blocks of basement of Siberian craton in Pre-Sayan area are overlaid by thick sequence of Mezo(?)-Neoproterozoic terrigenouscarbonate deposits united into Karagas and Oselok Group, which are interpreted to have formed along a passive margin [Sklyarov et al., 2002, Pisarevsky and Natapov, 2003]. The lower and middle Karagas Group contains a coarse sandstone, arkose, and conglomerate, intercalated with volcanic rocks, and may represent the rift stage of continental break-up [Sovetov, Komlev, 2005, Gladkochub et al., 2006]. The upper Karagas Group contains the predominantly turbidities and silicic and carbonate sediments [Sklyarov et al., 2002]. Due to the microphytholite and stromatolite data from the Karagas Group and regional stratigraphic correlation the age of sequence is determined within 850-720 Ma [Khomentovsky, 2002]. But, all of this succession is intruded by mafic dikes and sills of Nersa complex which were dated by the 40Ar/39Ar method on plagioclase at 741±4Ma [Gladkochub et al., 2006]. This and other geochronology as reported in [Gladkochub et al., 2006] indicates that sedimentary rocks of the middle Karagas Group were deposited at ~ 740 Ma, and the upper Karagas Group between 740 and 650 Ma. New geological data are also in a good agreement with these age estimations [Sovetov, Komlev, 2005]. The Karagas Group including dikes of Nersa complex is overlaid by sediments of Oselok Group with dolerites of Nersa complex in the pebbles of basal conglomerate [Sovetov, Komlev, 2005]. A discovery of tillite horizon in the base of Oselok Group correlative to Varanger Glaciation and findings of Metazoa biota just above the horizon suggests Vendian age of the Oselok group no more than 650 Ma [Sovetov, Komlev, 2005]. Mafic complexes analogous to Nersa dikes with the age 780-720 Ma are widespread on the southwestern margin of Siberia and due to [Sklyarov et al., 2003] can reflect rift-related magmatism associated with the break-up of Rodinia. On the basis on their age and geochemical studies it is possible that these dikes swarms could be related to the Franklin or Gunbarrel magmatic events in Laurentia or Mundine Well dikes in Australia [Sklyarov et al., 2003, Gladkochub et al., 2006]. Paleomagnetic study of Nersa dolerites [Metelkin et al., 2005c] and the sandstone of Lower and Middle Karagas Group [Metelkin et al., in progress] within the Pre-Sayan area (Birusa River) resulted in three stable components of remanence (Fig.3). Two of them are metachronous and the last one is ChRM and supposed as a primary by reversal test, fold test and baked contact test [Metelkin et al., 2005c]. We have studied two contacts of Nersa dikes. In the first observation Early Proterozoic granite was host rock for the dikes. An important feature of the baked rock there is dramatic (in one order or more) increase of natural remanent magnetization (NRM) and Koenigsberger ratio (Q) in the baked zone with respect to the host rock, caused by baking and oxidation. Although ChRM mean directions in the dolerites and the baked zone are statistically different (the angular distance γ=13.2° is more than the critical angle γc=10.9°) but their 95% confidence ovals overlap sufficiently. The deviation of ChRM direction in baked rocks from those in dolerites can be explained by magnetic anisotropy effect: the ratio of main axis of anisotropy of magnetic susceptibility kmax/kmin exceeds 1.37, in dolerite and 1.08 in baked zone.

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Figure 3. Geological map of the Biryusa area (modified from [Metelkin et al., 2005c]) and locations of paleomagnetic samples (a). Legend: 1 – Paleoproterozoic granitoids of Sayan complex, 2 – Neoproterozoic deposits of Karagas group, 3 – Vendian deposits of Oselok group, 4 – Neoproterozoic intrusions of Nersa complex; 5 – main faults; 6 – paleomagnetic sampling locations. Solid dot indicates the sampling site for isotope dating [Gladkochub et. al, 2006]. Below typical thermal demagnetization results of samples from Pre-Sayan trough after [Metelkin et al., 2005c] (b-g): (b-d) – dolerite of Nersa complex: (b) – dike-1, (c) – sill-2, (d) – sill-4, showing different remanence behavior during thermal demagnetization, shaded lines correspond to isolated components: C – low temperature viscous component, B – middle temperature metachronous component, A – characteristic component (ChRM); (e) – Karagas sandstone - A component close to ChRM of Nersa dolerites, (f-g) – contact rock baked by Nersa intrusions: (f) – granites of Sayan complex from of the exocontact of dike 1, (g) metasandstone (baked rock) of the exocontact of sill -4, dashed lines correspond to projections of stable components of remanence.

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The granites sampled at a 5 m distance from dike have a chaotic distribution of ChRM directions (precision parameter k1100 ~ 1100 ~ 1100 1098 ± 3 1095 ± 1 1090 ± 7 1087 ± 2 1087 ± 3 1075 ± 15

44 47.2 35 35 34 27 38 22 25 27

197 201.5 176 181 178 181 188 181 175 179

11 10.1 4 10 10 3 1 7 8 7

III-III

6

-IIII-I -IIIIII II--I-I II--I-I III-I-I III-I-I III-I-I IIIII-I

5 6 4 4 5 5 5 6

Halls, Palmer, 1981 Halls, Pesonen 1982 Halls, 1974 Halls, Pesonen 1982 Palmer, Davis, 1987 Diehl, Haig, 1994 Palmer, Davis, 1987 Lewchuk, Symons, 1990

MEAN POLE Nonesuch shale Freda sandstone

1100-1075 1050±30 1050±30

30.4 8 2

179.8 178 179

4.6 4 4

-IIII-I -IIII-I

5 5

Wingate et al., 2002 Wingate et al., 2002

Object

Siberia 1 Linok Fm., Uchur-Maya region 2 Malgino Fm., Uchur-Maya region 3 Lakhanda Gr., Uchur-Maya region 4 Ui Gr., including dolerite sill, Uchur-Maya region 5 Karagas Gr., Pre-Sayan trough 6 Karagas Gr., Pre-Sayan trough 7 Nersa complex, Pre-Sayan trough 8

11

Ust’Angara complex, Yenisey Ridge Red beds (sandstone), Transbaikalia Predivinsk complex, Yenisey Ridge Minya Fm., Transbaikalia

12

Shaman Fm., Transbaikalia

13

Mean Pole for Siberia

9

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10

Laurentia Abitibi dykes Seabrook Lake carbonatite Mean Logan sills Coldwell compleI

1

2

Q

Reference

Kazansky, 2002, Metelkin et al., 2005a Ernst, Buchan, 1993 Symons, 1992 Halls, Pesonen 1982 Lewchuk, Symons, 1990 Green et al., 1987

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D.V. Metelkin, A.Yu. Kazansky and V.A. Vernikovsky

176

Table 4. (Continued) №

Object

Laurentia Jacobsville sandstone Fond du Lac sandstone Eileen sandstone Amnicon and Orienta sandstone Chequamegon sandstone 3

4

5

6 7 8

Mean pole Grenville Thermochron Zone A Haliburton intrusions Archean Greenstone reset Nippissing diabase remag Temagami Granodiorites reset Gatineau Hills metamorphics Mean pole Wyoming dykes Tsezotene Fm. Tsezotene sills and dykes Little Dal redbeds Mean pole Natkusiak Fm. Franklin dykes Brock Inlier sills Mean pole Long Range dyke Calander compleI

Age (Ma)

Pole Lat

Long

A95(°)

~ 1020 ~ 1020 ~ 1020

-9 16 20

183 160 156

5 4 10

~ 1020

25

148

9

~ 1020

-12

178

5

1050-1020

7.3

169.3

14.9

~ 1000

1

159

6

980 ± 10 950-1000 950-1000 950-1000 ~ 900 950-1000 782 ± 8 ~ 780 778 ± 2 ~ 780 ~ 780 723 ± 3 723 ± 3 723 ± 3 ~ 720 615 ± 2 575 ± 5

-36 -5 -27 -37 -32 -22.9 13 12 2 -9 4.5 6 5 -2 3 -70 -46

143 152 141 150 155 150.3 131 146 138 143 138.8 159 163 165 162.3 172 121

6 11 8 8 5 14.9 4 8 5 11 13.7 6 5 16 8.1 15 6

Q

Reference

-II-I-I -II-I-I --I-I-I --I-I-I

4 4 3 3

Roy, Robertson, 1978 Watts, 1981 Watts, 1981

-II-I-I

4

McCabe, Van der Voo, 1983

-I--I-I

3

III-I-I ----I--I--I--I--I--I--II-

5 1 2 2 3

McWilliams, Dunlop, 1978 Hyodo, Dunlop, 1993 Hyodo et al., 1986 Hyodo et al., 1986 Hyodo et al., 1986 Irving et al., 1972

III-I-I --I-III III-I-I ---II-I

5 4 5 3

Harlan et al., 1997 Park, Aitken, 1986 Park et al., 1989 Park, 1984

III-III II-IIII -II-I-I

6 6 4

Palmer et al., 1983 Heaman et al., 1992 Park, 1981

I-III-I IIIII-I

5 6

Murthy et al., 1992 Symons, Chiasson, 1991

Watts, 1981

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Comment: Q - reliability classification scheme of Van der Voo (1990): “I” - condition fulfilled, “-“ condition not fulfilled, number means total score.

The APWP trend we assumed here is based on the compilation of paleomagnetic data sets form [Torsvik et al., 1996, Weil et al., 1998, McElhinny, McFadden, 2000, Meert, Torsvik, 2003, Pisarevsky, Natapov, 2003] and implies the same clockwise direction of polar wander within the Grenville Loop. However, the APWP for Laurentia is more richly supported by paleomagnetic data than Siberian one (Table 4) and for legitimate comparison of both loops we have generalized paleomagnetic poles from Laurentia within time intervals available for Siberian craton. Generalized APWP for Laurentia constructed in such a way does not only sufficiently differ from other APWP versions of Laurentia [McElhinny, McFadden, 2000, Pisarevsky, Natapov, 2003] both in shape and direction of rotation but also bears similarities to Siberian APWP [Metelkin et al., 2005a, 2007a]. The similarity of APW paths suggest kinematic similarity of those cratons between ~ 1000 Ma and ~ 700 Ma, which in turn implies the positions of Laurentia and Siberia in close proximity within Rodinia. The best fit of Late Mesoproterozoic interval of Siberian and Laurentian APW paths is achieved by 150º clockwise rotation of Siberian poles around the Euler pole of 77ºN 115ºE (Fig.7). After such rotation the western part of Siberia would lengthen the west margin of Laurentia to the north, as it was repeatedly proposed by [Rainbird et al., 1998, Pavlov, Gallet, 1999, Yarmolyuk, Kovalenko, 2001, Pisarevsky et al., 2008, Li et al., 2008]. This model does not require the

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presence of any free space between Laurentia and Siberia as it is assumed in [Pisarevsky et al., 2008, Li et al., 2008]. Due to the comparatively large confidence limits of Siberian paleomagnetic poles the presence of “missing link” of Early Precambrian block between northern margin of Laurentia and southern margin of Siberia [Pisarevsky et al., 2008, Li et al., 2008] is not unlikely, but is not necessary in light of new paleomagnetic data. It is more important, that Middle Neoproterozoic (~ 850 - 720 Ma) segments of the both APWP are latitudely shifted to ~ 50º relative to each other (Fig. 7). This gives the grounds to suggest a large-scale dextral strike-slips between southern margin of Siberia and northern margin of Laurentia during Neoproterozoic [Metelkin et al., 2007a]. Hence, it follows that at the opening stage of oceanic basin between Laurentia and Siberia the strike-slip motions were of considerable importance and triggered counterclockwise rotation of Siberian craton. Overall, the similar dynamics of Siberia-Rodinia break-up during Neoproterozoic is supposed on the base of geochronologic data and geological correlation between Aldan-Transbaikalian and North Canadian regions [Yarmolyuk, Kovalenko, 2001]. According to the proposed model (Fig. 8) the most ancient complexes correlated to the initial stage of rifting in the south of Siberia seems to be dikes and sills in sedimentary sequence of Ui group from Uchur-Maya region with an age of 950-1000 Ma [Rainbird et al., 1998]. Most likely, the separation of Siberian continent has already started at this time. The opening of the oceanic basin between Siberia and Laurentia occurred gradually from west to east, very similar to modern Red Sea rift but with the sufficient strike-slip component [Yarmolyuk, Kovalenko, 2001, Metelkin et al., 2007a]. Such geodynamic environment was probably resulted from the development of subduction zone on the northern margin of Siberia, active island arc magmatism is recognized since 960 Ma ago [Metelkin et al., 2003]. At this time, western and eastern margins of “Siberian peninsula” represented an area of quite sedimentation in the passive margin tectonic environment [Pisarevsky, Natapov, 2003, Pisarevsky et al., 2008]. Paleomagnetic data form Meso-Neoproterozoic of Australia, as one of the large continental blocks of East Gondwana being compared with Laurentian APWP suggest a similar kinematic of ocean opening in the western margin of Rodinia between the Laurentia and East Gondwana [Wingate, Giddings, 2000, Powell, Pisarevsky, 2002]. Following the interpretation by [Wingate and Giddings, 2000] Mesoproterozoic poles from East Gondwana (Australia) well coincide with Laurentian poles after 127 degrees counterclockwise rotation around the Euler pole of 34.6ºN, 134.6ºE. In such case Australian paleomagnetic pole for 755 Ma (Mundine Well dyke swarm, Western Australia) falls 30 degrees apart from the corresponding segment of Laurentian APWP [Wingate, Giddings, 2000]. Comparison of paleomagnetic data from Australia and Laurentia allows to conclusion that during the first part of Neoproterozoic (1000-750 Ma) the cratons of East Gondwana exhibited a sinistral strike-slip motion along the west margin of Laurentia with the progressive opening of oceanic basin from north to south (in modern coordinates of Laurentia). By this means the break-up scenario of eastern part of Rodinia as a whole can be driven by ‘tectonic crawl away” of several cratons: East Gondwana, Laurentia and Siberia resulted from the counterclockwise rotation of the whole assemblage (Fig. 8). In doing this, cratons of East Gondwana located on the west periphery of Rodinia show the maximal rotation while Siberian craton at the northern periphery “lags behind” of common total motion. There is a dextral strike-slip motion of Siberian craton relative to Laurentia which comprises the stable core of the

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Figure 8. Paleotectonic model of Rodinia break-up during Neoproterozoic after [Metelkin et al., 2007a ) For 1000-950 Ma reconstruction we used the following Euler rotations: Australia to India 4.79ºS 15.35ºE 64.75º [Powell et al., 1988], E. Antarctica to India 4.22ºS 17.14ºE 92.45º [Powell et al., 1988], South China to India 43.7ºN 118.8ºE 106.1º [Li et al., 1995]. After this the whole East Gondwana assemblage (in Indian coordinates) was rotated to Laurentia 56ºS 339ºE -166º [Powell et al., 1993] and then Laurentia-East Gondwana system (in Laurentia coordinates) was rotated to Siberia 77ºN 115ºE 150º [Metelkin et al., 2007a]. For reconstruction of spatial position of Rodinia (in Siberian coordinates) we used mean pole from Ui group 4.9ºN 357.7ºE A95=4.2º (including data from dolerite sills) [Pavlov et. al., 2002]. Euler rotations for West Gondwana are taken from [Li et al., 2008]. For 900-850 Ma reconstruction Laurentia and East Gondwana are placed in respect to Siberia into intermediate position between 1000-950 Ma and 780-720 Ma reconstructions. For spatial position of Rodinia (in Siberian coordinates) we used interpolated pole from Siberian APWP at 10ºS 300ºE. For 780-720 Ma reconstruction we use the following Euler poles: Eats Gondwana blocks the same as for 1000-950 Ma, then East Gondwana assemblage (in Indian coordinates) was firstly 7.5ºN 303ºE 33.9º according to [Wingate, Giddings, 2000] and afterwards rotated to Laurentia 56ºS 339ºE -166º, so that Mundine Well dyke swarm pole fits interpolated pole position from Laurentia at 755 Ma in accordance with [Wingate, Giddings, 2000]. After this we rotate Laurentia-East Gondwana assemblage (in Laurentia coordinates) to Siberia 77ºN 115ºE -150º and than shifted at 50º westward up to coincidence of Laurentian pole for 755 Ma with mean pole from dikes and sills of Nersa and Ust’Angara complexes (in Siberian coordinates For spatial position of Rodinia (in Siberian coordinates) we used mean pole from dikes and sills of Nersa and Ust’Angara complexes 20.5ºN 309.8ºE A95=9.6º [Metelkin et al., 2007a].

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assemblage (Fig. 8). The lack of paleomagnetic data for 900-850 Ma reconstruction we have to use interpolated pole position 10ºS, 315ºE from Siberian APWP due to the lack of paleomagnetic data for this age. This pole corresponds to the south most position of cratonic assemblage in Neoproterozoic. At this time, the modern southern margin of Siberia can be located at 40-50ºS (Fig. 8). After ~900 Ma, the passive margin in this area has been transformed into an active margin [Vernikovsky et al., 2004]. Since this time probably all north-western periphery of Siberian plate was fringed with the island arc system and related marginal seas. Subduction in the north-west of Siberian plate were compensated by the growth of oceanic crust in the south-west. Revealing of one or other process has determined the rotation of Siberian craton. The 780-720 Ma stage in the southwestern margin of Siberian craton is marked by subvolcanic intrusions which are suggested [Sklyarov et al., 2003, Gladkochub et al., 2006], to reflect the break-up of Rodinia. If this, is the case then at least the Pre-Sayan margin of Siberia should be in the contact with Laurentia yet. Following this assumption and the regularities in paleomagnetic poles distribution, we propose an juxtaposition of Siberia and Laurentia (Fig. 8). During the first part of Neoproterozoic, Siberian craton have to be shifted relative to Laurentia over a distance of 2000 km. In the context of this reconstruction southwestern margin of Siberian craton was located in vicinity of the northern margin of Greenland (Fig. 8). Conceptually, only Pre-Sayan appears to be this narrow stripe of contact between Siberia and Laurentia at this time. The rest of Siberian margins should be connected with an ocean space. For example the ~ 750 Ma border in Yenisei Ridge is connected with collision of Central Angara terrane [Vernikovsky et al., 2003], in the south of Siberia the processes related to oceanic basins are also dominated [Khain et al., 2003], the east of plate was a passive margin open to the ocean [Pisarevsky, Natapov, 2003]. Due to the geological data the assumption that disintegration of Siberia and Laurentia had occurred earlier - in the beginning of Neoproterozoic [Dobretsov et al., 2003, Yarmolyuk, Kovalenko, 2001] appears to be more plausible. In general, the viewpoint does not contradict with paleomagnetic data. We only have to accept a small-sized ocean space, that is resulted from rifting between Laurentia and Siberia, and its continental margins have undergone the transform strike-slip displacements relative to each other, as it shown in the reconstruction. In any case, according to paleomagnetic data, dike swarms from southwest of Siberian craton unlikely related to Mackenzie or Franklin Large Igneous Provinces as is proposed in [Sklyarov et al., 2003, Gladkochub et al., 2006, Pisarevsky et al., 2008]. More likely that those rift-related complexes have formed during ~ 750 Ma orogeny on the southwest of Siberia or represent the individual magmatic province resulted form the last stage of break-up of Laurentia and Siberia. The continuation of the tectonic history in Neoproterozoic (700 - 600 Ma) is connected with Siberian paleocontinent completely surrounded by an oceanic space. A subductionrelated complex of the same age was identified in the Baikalian part of southern Siberia [Khain et al., 2003]. Remains of ophiolites and island arc complexes of 700-630 Ma are known in the north and west of Siberia [Vernikovsky et al., 2003, Vernikovsky et al., 2004]. Our tectonic model allows that this time is connected with the evolution of extensive island arc system along the west (in modern coordinates) margin of Siberian craton as it suggested by [Vernikovsky et al., 2003]. Accretion and obduction of the system in the beginning of Vendian (~ 620-600 Ma) resulted in the development of large-scale Late Neoproterozoic folded belt. Remains of the belt is preserved in the folded-napped structure of Sayan-Baikal

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and Taimyr areas [Vernikovsky et al., 2003, Vernikovsky et al., 2004]. But, even in the end of Vendian the environment of active continental margin has been recommenced at least in the south-west of Siberian plate [Dobretsov et al., 2003].

3. VENDIAN TO CAMBRIAN ACTIVE CONTINENTAL MARGIN ON THE SOUTH-WESTERN FRAME OF SIBERIA 3.1. Short Prelude

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The Late Precambrian to Early Paleosoic tectonics of Southern Siberia reflect the closure stage of so-called Paleoasion Ocean is hotly debated for a long time [Zonenshain et al., 1990, Sengor et.al., 1993, Buslov et al., 2001, Dobretsov et al., 2003]. On modern structure of Siberia this territory is represented by Altay-Sayan orogen which comprises a part of Cenrtal Asia Folded belt (Fig. 9). As a whole Altai-Sayan including a lot of island arc terranes is considered to be one of the mosaic in tectonic structure. Among the strikes of its fragments NEE and EW directions are prevailing. Unclear junctions of different zones are usual in this area (Fig. 9). The structure of Altai-Sayan area reflects a large-scale displacement along the strike-slips and multiple characters of accretion processes [Berzin, Dobretsov, 1994, Kungurtsev et al., 2001].

Figure 9. Main structure of Alati-Sayan area modified from [Kungurtsev et al., 2001] Legend: 1 - Siberian craton with NP-PZ cover; 2 - microcontinents with NP cover; 3 - island arc terranes (V-O1); 4 - oceanic terranes with ophiolites (NP3 -Є1); 5 - overlapping deposits of continental slope and shelf, undivided (PZ1); 6 - overlapping volcanо-sedimentary deposits of PZ2-PZ3 troughs; 7 Mesozoic-Cenozoic plate complex; 8 - main faults; 9 - other faults and geological boundaries.

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The mostly debated Vend Cambrian interval is connected with the development of island arc system along the periphery of Siberian continent and drastic close of oceanic basin that caused the growth of continental crust and intensive Caledonian orogeny and resulted in the development of accretionary structure of Altai-Sayan [Zonenshain et al. 1990, Khain et al., 2003]. The fragments of Vendian-Cambrian island arc complexes are widespread in Kuznetsk Alatau, Gorny Altai, and West Sayan (Fig. 9) and also in Eravna zone of Baikal-Vitim area [Khain et al., 2003]. At the moment a number of fundamentally different models of evolution of Altai-Sayan folded area are known [Zonenshain et al., 1990, Sengor et.al. 1993, Didenko et al., 1994, Kungurtsev et al., 2001]. The main differences are connected with paleopositions and relations between terranes and in consistence the kinematics of accretionary process. Some scientists suggest that in Vendian-Cambrian the most of island arc terranes of AltaiSayan orogen comprised a single island arc system along margins of Siberian paleocontinent [Zonenshain et al., 1990, Sengor et al., 1993, Kungurtsev et al., 2001]. Alternative models are proposed that Vend-Cambrian island arc terranes considered as a number of individual arcs developed along the periphery of the paleocontinent and the ocean itself is represented by small basins separated by the microcontinents [Mossakovsky et.al., 1993; Didenko et al., 1994, Buslov et al., 2001].

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Table 5. Vendian-Early Cambrian paleomagnetic poles from island arc terranes of Altai-Sayan folded area. N

Terrane

Age (Ma)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Kurtushiba Kurtushiba North Sayan North Sayan North Sayan Gorny Altay Gorny Altay Bateni Bateni Gold Kitat Gold Kitat Kiya Kiya Kiya Kiya Tersa Tersa Eravna Eravna Siberia (mean pole) Siberia (mean pole)

V-Є1 (560-520) Є2-3, (520-500) Є1 (540-520) Є1 (540-520) Є2-3 (520-500) V-Є1 (560-520) Є2-3 (520-500) Є1 (540-520) Є2 (520-510) Є1 (540-520) Є2-3, (520-500) V-Є1 (550-530) Є1-2 (530-510) Є2-3, (510-490) O1 (490-470) V-Є1 (560-520) Є2-3, (520-500) Є1 (540-520) Є2-3 (520-500) Є1 (560-545) Є3 (500)

Test

Lat -27.1 F+ -38.1 R, F+,C+ -5.5 F+ -17.7 F+ -36.3 R, F+ 14.4 R, F+ -38.4 F+ -28.6 R, F+ -38.4 -1.2 R, F+ -14.9 F+ -23.0 F+ -35.0 F0 -43.1 F+ -44.0 F0 -15.6 F+ -37.6 F+ 21.0 F+ -50.6 -29.3 -36.0

Pole Long 129.9 130.8 147.6 122.6 134.9 0.7 140.4 81.3 152.2 26.8 176.4 62.5 86.2 109.1 129.6 44.0 132.2 8.8 124.1 59.7 129.0

A95 5.7 4.1 4.0 4.6 5.6 6.0 4.5 7.7 6.6 5.0 3.3 3.6 3.2 5.4 5.5 8.0 6.3 4.7 1.8 8.3 8.0

Reference Didenko et al., 1994 Metoelkin et al., 1997 Kazansky et al., 1999 Kazansky, 2002 Kungurtsev et al, 2001 Kazansky et al., 1998 Kazansky, 2002 Merkulov, 1982 Metelkin et al., 2000 Kazansky, 2002 Metelkin et al., 2000 Kazansky et al..2003 Kazansky et al..2003 Kazansky et al..2003 Kazansky et al..2003 Kazansky et al., 2003a Kazansky et al., 2003a Metelkin et al., 2006 Metelkin et al., 2006 Kazansky, 2002 Didenko, Pechersky, 1993

Comment: Test -paleomagnetic tests: R - positive reversal test, F+ - positive fold test (“о” - means test inconclusive); С+ - positive baked contact test; : Lat, Long - pole latitude (N degrees) and longitude (E degrees) respectively, А95 - radius of 95% confidence oval,

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Figure 10. Geological sketch map of Kuznetsk Alatau modified from [Kazansky et al., 2003a] 1-2 - complexes of intraplate oceanic islands в (1 - volcanic, 2 - carbonate, a - in accretionary wedge, b - in island arc basement); 3-7 - complexes of immature island arc: 3 - ohpiolyte, 4 - volcanic, 5 carbonate , 6-7 - predominantly intrusive: 6 - gabbride, 7 - granitoid; 8-9 - complexes of mature island arc: 8 - volcanic, 9 - granitic; 10-11 - complexes of oblique collision environment: 10 - granitic, 11 volcanic; 12 - complexes of Hercynian troughs; 13 - faults, dividing main blocks (a) complicating faults (b).

We shall give a brief summary of available paleomagnetic data set for Altai-Sayan orogen on Late Vendian - Cambrian time (Table 5) that allows verifying and sufficient improving of geodynamic reconstructions. Some of relatively large Vend-Cambrian island arc terranes are well studied now and their geological sketches are presented.

3.2. The Kuznetsk-Alatau Terranes Main structure of Kuznetsk Alatau consists of four large tectonic units: Gold Kitat, Kiya, Tersa, and Bateni terranes (Fig. 10). Gold Kitat terrane is represented by the complexes of external part of paleoisland arc (accretion wedge and fore-arc trough). Kiya terrane is mainly composed of the magmatic arc complexes. In Tersa and Bateni terranes the complexes of magnatic arc grade into the complexes of inner slope of paleoarc and than more deep-water complexes of back-arc basin [Kheraskova, Gavrilova, 1996, Berzin, Kungurtsev, 1996, Metelkin et al., 2000]. Three main stages can be recognized in the tectonic of the region by

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corresponding geological complexes [Berzin, Kungurtsev, 1996]. The first stages respond to the primary island arc that consists of Vendian to Cambrian primitive tholeiites dominantly. The second stage is represented by Middle and Late Cambrian volcanics of island arc type. These one includes the differentiated series of calc-alkaline and sub-alkaline composition and abundant pyroclastics. The third stage connects to Early Ordovician accretion and defines by the molasses and alkaline volcanic complexes. We obtained the Late Vendian to Early Ordovician paleomagnetic poles for all main terranes of Kuznetsk Alatau. [Metelkin et al., 2000, Kazansky, 2002, Kazansky et al., 2003a, 2003b]. Generally, the primary origin of remanence is supported by the fold test and reversal test.

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3.3. The West Sayan Terranes Three main tectonic units consist of West Sayan: North Sayan, Central Sayan and Kurtushiba terranes (Fig. 11). Ordovician to Silurian sediments overlap the accretionary structure of Central Sayan unit. Vendian to Cambrian island arc complexes comprise North Sayan and Kurtushiba terranes. Nearly the entire set of island arc has been preserved in North Sayan. The Vendian to Early Cambrian terrigenous rocks interbedded with basalt, tuff and marble as well ophiolites comprise the accretionary wedge of the frontal arc along the southern margin of North Sayan [Simonov et al., 1994]. The fore-arc and volcanic arc complexes developed along the northern margin [Berzin, Kungurtsev, 1996, Kazansky et al., 1999]. These consist of Vendian to Cambrian primitive tholeiite, while Middle and Late Cambrian represent by basalt, andesite and dacite defines developed differentiated series of island arc type [Berzin, Kungurtsev, 1996]. The back-arc complexes preserve to the northwest of North Sayan, where Cambrian flysch-like deposits dominate. The Kurtushiba terrane situated along the south of West Sayan consist of mainly frontal arc complex with ophiolites abundance. Paleomagnetic results [Didenko et al., 1994, Metoelkin et al., 1997, Kazansky et al., 1999, Kazansky, 2002, Kungurtsev et al., 2001] allow to determine paleoposition of Kurtushiba and North Sayan terranes and to prove their present day configuration as resulted of strike-slips [Kungurtsev et al., 2001]. A number of paleomagnetic tests such as baked contact, reversal and fold test supports Cambrian age of remanence and validity of tectonic compilations.

3.4. The Gorny Altai Terrane A number of areas where island arc volcanics widespread are recognized in Gorny Altai [Buslov et al., 2001]. The southeast of Gorny Altai is considered as a possibly equivalent structure of North Sayan and consist of mainly volcanic formations of island arc type as well complex of accretionary wedge. The geological features of the central place is more close to the Kuznetsk Alatau terrane with the predominant Middle - Late Cambrian volcanic formations of island arc as well back arc turbidite. The northwest of Gorny Altai is represented by the complex of frontal arc [Berzin, Kungurtsev, 1996]. Geological and paleomagnetic studies of Gorny Altai [Kazansky et al., 1998, Kazansky, 2002] assume that modern structure of this terrane resulted from a tectonic recombination of different fragments

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of Vendian-Cambrian island arc displaced along submeridional strike-slips [Kungurtsev et al., 2001].

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Figure 11. Geological sketch map of West Sayan modified from [Metelkin et al., 1997] 1-11 - complexes: 1 - outer slope of island arc; 2 - accretionary wedge; 3 - ophiolites in accretionary wedge; 4 - hyperbasite bodies in ophiolite complex; 5 - forearc trough; 6 - volcanic arc; 7 - undivided deposits of volcanic arc and forearc trough; 8 - backarc basin; 9 - plagiogranitic intrusions и; 10-11 overlapping deposits: 10 - Ordovician-Silurain 11 - Devonian; 12 - faults, including strike-slip faults (a);

3.5. The Eravna Terrane Units Eravna terrane is situated southward from Lake Baikal at the periphery of Baikal-Vitim folded area [Parfenov et al., 1995]. The Cambrian volcano-sedimentary formations of island arc type are distributed along the Uda river among Middle Paleozoic granitoids of giant Angara-Vitim Batholite. This formations can being completely compared by West Sayan and other Early Paleozoic island arc terrane of Altay-Sayan area. The most characteristic member is basalt to andesite formation of Lower Cambrian refers to a typical island arc. This includes basalt, andesite, tuff, aglomerates and arhaeoceate bioherms. Volcanic formations of Dzhida and Tannuola-Khamsara areas (Fig. 9) might be links of Eravna (Uda-Vitim) arc to other island arc terrane of Altay-Sayan [Gordienko, 2006]. First preliminary paleomagnetic studies of Cambrian volcano-sedimentary sequence of Eravna terrane result in two groups of remanence of prefolding age [Metelkin et al., 2006]. Those groups can reflect position of Eravna arc both in Vendian/Cambrian boundary when active volcanism related to subduction widespread along the southwestern margin of Siberia as well in Late Cambrian when accretion arcs to Siberia was happened. Paleomagnetic poles calculated from those groups coincide to the even-aged poles from Altay-Sayan island arc terranes and will being analyze together [Metelkin et al., 2006].

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3.6. Discussion about Paleomagnetic Data and Tectonic Implication A specific law governs the pole positions of the Siberian island arcs. The poles for Vendian-Cambrian time distribute along the great circle with the center at 58°N, 111°E (Fig. 12). Most surprising is it very closed to Euler pole of Mesozoic rotation for Siberian plate proposed by [Zonenshain et al., 1990, Voronov, 1997] on the base of same geological evidence. In any case a good agreement of pole positions testifies that island arc terranes probably were compound a single island arc, which after deformed by strike-slips. The island arc system itself was located near equator (5°-15°N) and had sub-latitudinal orientation. As mentioned above paleomagnetic pole position for Vendian/Cambrian boundary is debated [Kirschvink, Rozanov 1984, Kirschvink et al., 1997, Smethurst et al., 1998, Kravchinsky et, 2001, Kazansky, 2002, Shatsilo et al., 2005 Metelkin et al., 2005a]. If we assume the west trend of Neoproterozoic segment of Siberian APWP [Metelkin et al., 2005a], that is in a good agreement with Neoproterozoic reconstructions, then the most plausible paleomagnetic poles for Late Vendian are those from [Kravchinsky et al., 2001, Kazansky, 2002] (see table 4 and 5). For the reconstruction (Fig. 13) we used the mean pole from Siberia at 560-540 Ma: 29.3°N, 59.7°E, A95=8.3 [Kazansky, 2002, Metelkin et al., 2005a]. This pole is closely located to Vendian-Cambrian poles from Kuznetsk Alatau and accurately fits the pole from Kiya terrane. Using this we assume that the island arc system was surrounded the western margin of Siberian continent at the Vendian/Cambrian boundary (Fig. 13). Deformation of this system at the end of Cambrian and Ordivician related to accretion process (as well later deformations during Late Paleosoic and perhaps Mesozoic also) connect to strike-slips that dominantly caused by rotation of Siberian plate. Due to the rotation the structures of periphery of the continent “lagged” and shifted, making up individual tectonic blocks which during the interaction underwent complex movements [Kungurtsev et al., 2001, Kazansky, 2002]. It is resulted in the modern collage that is characterized by variety in the strikes and unclear junctions of different structural elements of folded area. Due to the paleomagnetic data Siberian continent during Cambrian was drifting southward rotating clockwise [Didenko, Pechersky, 1993]. Such kinematics in stress environment on the boundary between continental and oceanic plates leads to the development of strike-slip faults along the periphery of the continent and subsequently to the deformation of island arc system. The displacements of island arc fragments can occur along the strike-slips in the back ark as well as along the oblique subduction zones [Kungurtsev et al., 2001]. Available paleomagnetic data for the island arcs do not statistically coincide for Late Cambrian (Table 5, Fig. 12). However, they are very close to each other and to the corresponding interval of APWP for Siberian craton (except the pole from Gold Kitat terrane). It should be mentioned that APWP version is used here for Siberia by [Didenko, Pechersky, 1993] that for Late Cambrian-Ordovician interval does not sufficiently differ from versions by [Smethrust et al., 1998, Cocks, Torsvik 2007].This suggests that up to the end of Cambrian, tectonic units of southwestern margin of Siberia have the mutual position close to the present day. Some differences in individual pole positions (Fig. 12) indicate that intensive deformation of paleoisland arc system and back arc basins under the strike-slip conditions that begin in Cambrian has continued in Post-Cambrian time also.

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Figure 12. a) Vendian - Cambrian paleomagnetic poles from island arc terranes of Siberian frame. Black dots with stars and confidence ovals represent mean poles from Siberia (see Table 5); b) The best fitting great circle for Vendian-Early Cambrian poles Comment: all pole numbers correspond to numbers in Table 5.

Figure 13. Paleotectonic reconstruction for Siberian frame in Late Vendian-Early Paleozoic, modified from [Kazansky, 2002]). 1-3 Siberian craton: 1 - marginal sea shelf deposits, 2 - riff deposits, 3 - Laguna-type deposits, 4 oceanic crust, 5 - accretionary and forearc complexes of island arc; 6 - complexes of magmatic arc; 7 back-arc basins, 8 - spreading zones, triangles show the position of MORB basalt of Dzhida zone based on paleomagnetic data by [Gordienko, Mikhaltsov, 2001] small circles show the position of WPOIBtype subalkaline basalt of Dzhida zone based on paleomagnetic data by [Gordienko, Mikhaltsov, 2001], thin dashed line indicates proposed absolute motion of oceanic crust over the hot spot, 9 - subduction zones, 10 - Late Cambrian accretionary complexes, contours show the positions pf island arc fragments of Vendian Cambrian paleoisland arc system: GK - Gold Kitat terrane, KI - Kiya terrane, TR - Tersa terrane, BT - Bateni terrane, GA - Gorny Altay terrane, NS - North Sayan terrane, KT - Kurtushiba terrane, ER - Eravna terrane.

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The main mechanism for driving sinistral strike-slips and controlled deformations of the Altay-Sayan accretional structure seems to be the process of “lagging” and slipping of individual elements within the periphery of Siberian plate as the result of the drift itself along with its clockwise rotation. So, as the result of the whole process the relative movements of Eravna terrane described by the strike-slip and position of Eravna in the modern structure of the Central Asia is apart from their primary neighbors. As well dextral strike-slip of Kurtushiba terrane southwestward along North Sayan terrane is resulted from this common process. The relative movement between terranes seems to be completed up to the end of Devonian only [Berzin, Dobretsov, 1994]. In Middle and Late Paleozoic strike-slips connected with the lag of accretional structures from periphery of Siberian craton are known in Gorny Altai and Western Mongolia also [Kungurtsev et al., 2001, Kazansky, 2002]. Late Cambrian paleomagnetic pole from Gold Kitat terrane might be coincide to Siberian one by 45°-50° clockwise rotation around Euler pole of 52°N 106°E. It is again very close to those we have determined for Vendian and Early Cambrian. In the framework of our model, this point represents Euler pole of Siberian plate rotation during early Paleozoic. In this case, the fact of particular interest is the trend of Vendian-Early Paleozoic poles from Kiya terrane (Fig. 14). APWP, constructed for Kiya terrane [Kazansky et al., 2003a] shows that during Vendian up to Ordovician (from ~ 540 to 480 Ma) the pole had a sublatitudal drift of SE direction due to the sufficient clockwise rotation of terrane, similar to as it is supposed now for Siberia. 540 Ma paleomagnetic pole from Kiya terrane is located near the Madagascar (the same pole position we suppose for Siberian continent), and that the pole is wandering to the southwestern coast of Australia and 500-480 Ma poles from Kiya and Siberia almost coincide. Finally, Vendian and Cambrian poles follows the arc around the Euler pole of 48°N 126°E, which is in a close proximity to the Euler pole of Siberian plate. We assume that the kinematics of Kiya terrane (Fig. 14) is very close to those of Siberian plate. Most likely, that Siberian plate and the area of island arc magmatism on its margin controlling by subduction drifted from the north to south, from equatorial (~ 10°N) latitudes to more moderate ones (~ 15°S) together. The rate is estimated not less than 1 °/Myr (Fig. 14). The southern drift was complicated by the ~ 50° or more clockwise rotation. The rotation became one of the reasons that determined the deformations along the periphery under the strike-slip environment. The proposed model (Fig. 14) explains the present day mosaic structure of Paleozoic accretionary zone of the southwestern frame of Siberian craton.

4. LATE PALEOZOIC EURASIA ASSEMBLY AND TRAP MAGMATISM INTO SIBERIA 4.1. Late Paleozoic Tectonic Introduction Late Paleozoic stage of Siberian history is infilled with the geological events. The most pronounced among them is the assemblage of Pangaea supercontinent [McElhinny, McFadden, 2000]. Up to the end of Paleozoic closure of Late Precambrian - Early Paleozoic oceans and collision between Siberian, Baltica and Kazakhstan paleocontinents [Sengor,

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Figure 14. APWP for Kiya terrane after [Kazansky et al., 2003a] in comparison with Siberian APWP (after [Didenko, Pechersky, 1993]) (upper panel) and kinematic parameters of Kiya terrane from Late Vendian to Early Ordovician (lower panel) .

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Natalin, 1996] made up the basic structure of Eurasian plate [Zonenshain et al., 1990]. One of the pronounced events for Siberia at the stage of supercontinent assemblage seems to be its collision with Kara microcontinent exposed in the northern part of the Taimyr fold belt in the Taimyr Peninsula and the Severnaya Zemlya Archipelago. Many researches support the idea that Kara is exotic to the Siberian craton and have been accreted to it only during the Late Paleozoic [Zonenshain et al., 1990, Uflyand et al., 1991, Vernikovsky et al., 1995, Bogdanov et al., 1998, Metelkin et al., 2005b, Cocks, Torsvik, 2007]. The paleomagnetic evidence [Metelkin et al., 2005b] clearly show that the Paleozoic tectonic evolution of the Kara microcontinent was dominated by the strike–slips associated with a transform margin that resulted in the collision with the Siberian craton in the Late Carboniferous to Permian. This interpretation provides a new foundation to explain the Paleozoic history of Arctic Siberia at the stage of Pangaea assemblage. The completion of large tectonic event of involving of Siberian continent into Pangaea assemblege at the Permian/Triassic boundary was manifested by dramatic explosion of intraplate magmatism resulted in formation of Siberian Large Igneous Province (LIP). Many researchers have considered the widespread Permo-Triassic magmatism of northern Eurasia to be a reflection of a plume or superplume [Sharma, 1997, Dobretsov, 1997, Yarmolyuk et al., 1997, Zolotukhin, 1998, Dobretsov, Vernikovsky, 2001]. The Siberian LIP is one of the largest known regions of plume magmatism in terms of the volume of magmatic products (basalt, tuff, dolerite and other associated rock types). Permo-Triassic trap magmatism is widely distributed on the Siberian platform [Zolotukhin, 1998], beneath a cover of Mesozoic– Cenozoic deposits in the West Siberian basin and in the southeastern Kara Sea [Dobretsov, 1997; Bogdanov et al., 1998], and also on the Taimyr Peninsula [Dobretsov, Vernikovsky, 2001]. Much research is devoted to the geologic aspects of Siberian Large Igneous Province [Zolotukhin, Al’mukhamedov, 1988, Lind et al., 1994, Al’mukhamedov et al., 1999, Dobretsov et al., 2005 and other]. One of the least known appearances of Siberian trap magmatism is the traps of Kuznetsk trough in the South Siberia. The paleomagnetic results from basalt of Kuznetsk traps are represented here and on the base of combination of geologic and paleomagnetic data its connection with traps from Noril’sk, West Siberia and Taimyr is demonstrated. The proposed correlation provides some new evidence on Siberian tectonic at Paleozoic/Mesozoic boundary.

4.2. Late Paleozoic Kara - Siberia Collision and Global Paleozoic Reconstruction The Taimyr–Severnaya Zemlya fold-thrust belt is situated in Arctic Siberia along the Kara Sea coast between the Ural–Novaya Zemlya fold belt to the west and the Verkhoyansk fold belt to the east (Fig. 15). It is subdivided into the southern (Siberian margin), central (Neoproterozoic accretionary belt) and northern (Kara microcontinent) domains separated by the major Pyasina–Faddey and Main Taimyr thrusts. The Taimyr margin of the Siberia has undergone at least two stages of deformation, i.e., Late Neoproterozoic and Late Paleozoic– Early Mesozoic [Zonenshain et al., 1990, Vernikovsky, 1996, Inger et al., 1999, Vernokovsky, Vernikovskaya, 2001]. The last is connected with Siberia - Kara collision [Vernokovsky et al., 1995, Metelkin et al., 2005b]. The geological complexes of Kara microcontinent exposed on the northern part of the Taimyr Peninsula and Severnaya Zemlya

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Archipelago. Continuity of geophysical data (aeromagnetic and gravity) suggests that structures in the Eraly Precambrian basement of microcontinent continue across much of the Kara shelf [Bogdanov et al., 1998]. The main structures in the Kara, including major dextral strike–slip faults, are sub-parallel to the arc of the collisional belt (Fig. 15). To the west, the plate is abruptly terminated by the N–S-trending St.Anna trough, which is expressed in the modern relief of the sea-floor as a neotectonic trench [Matishov et al., 1995]. The southern boundary of the Kara is marked by dextral strike–slip faults [Bogdanov et al., 1998], and the northern and northeast margins of the plate are truncated by the Nansen depression of the Arctic Ocean. The Taimyrian part of the Kara plate is represented by Neoproterozoic– Cambrian flysch-like deposits - rhythmically alternating sandstone, siltstones, and pelites, that can be interpreted as the continental slope sediments. The internal structure of this zone is complicated by Late Palaeozoic regional 300–265 Ma metamorphism and granite intrusion [Vernikovsky et al., 1995, Vernikovsky et al., 1998a]. The Neoproterozoic–Cambrian flyschlike deposits of Severnaya Zemlya Archipelago are covered by Ordovician–Devonian strata of shallow-water, lagoonal, and coastal-marine facies [Pogrebitsky, 1982, Vernikovsky, 1996]. The paleomagnetic results for Paleozoic complexes of Severnaya Zemlya Archipelago are given in [Metelkin et al., 2005b] in details. We shall restrict our consideration to tectonic analysis of the paleomagnetic data that can shed light upon Paleozoic history of Kara microcontinent as well as upon Paleozoic tectonics of the whole Siberia. Paleomagnetic poles for three consecutive time intervals, i.e., Late Cambrian–Early Ordovician (26.9°S 255.5°E A95=11.6), Middle–Late Ordovician (10.1°S 212.0°E A95=12.0) and Late Silurian (10.5°N, 183.5°E A95=8.8°) have been determined. The primary genesis of remanences obtained is supported by the fold test and therefore allows the construction of an APW path for the Kara microcontinent [Metelkin et al., 2005b]. The comparison of this APW path with the available paths for Siberia [Didenko, Pechersky, 1993 Cocks, Torsvik 2007] and Baltica [Torsvik et al., 1996] is used here for the illustration of independent character of Kara drift during Paleozoic and also to provide a rough idea of available paleomagnetic evidence of kinematics of main tectonic units of Eurasia during Paleozoic before their collision (Fig. 16). As it shown in Figure 16, Kara like as Siberia and Baltica during Paleozoic underwent predominantly northward drift. The APW path for Kara starting from margin of South America at around 25°S (Late Cambrian) and ending up at ca. 10°N in the West Pacific (Late Silurian). Late Paleozoic (Devonian to Permian) poles from Kara have not yet been obtained. But, it is quite clear that the wandering of Kara paleomagnetic poles (as well as terrane itself) fits an arc of the great circle with Euler pole of 60.5°S. 112.1°E. We believe that the reconstructed kinematics Kara (Fig. 16) has not changed up to the moment of collision. If one interpolates APW path of Kara for Late Paleozoic taking to account the stable legitimacies found in terrane motions in the beginning of Paleozoic, the concurrence of APW path’s of Siberia, Baltica and Kara will be achieved in an interval of 300-250 Ma (Fig. 16). It is completely corresponds to the geological evedence of Kara and Siberia collision [Vernikovsky et al., 1996] and close to the Eurasian part of Pangaea assembled.

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Figure 15. Tectonic scheme of the North Siberia and Kara Sea modified from [Metelkin et al., 2005b] Legend: 1-2 - Siberian craton: 1 – Archean and Paleoproterozoic basement, 2 - Phanerozoic cover (a), including Paleozoic and Early Mesozoic sediments of the South Taimyr Domain (b), 3 Neoproterozoic accretionary belt (Central Taimyr Domain): metamorphic terranes with 920-850 Ma granite (a), passive continental margin terranes with Neoproterozoic carbonate deposits (b), island arc and back arc terranes, ophiolite with 700-630 Ma plagiogranite (c), Vendian to Early Carboniferous sedimentary cover (d); 4 - Kara microcontinent (North Taimyr Domain): Neoproterozoic to Cambrian turbidites of the Kara continental slope (a), Paleozoic coastal-marine, lagoonal and continental sediments of the Kara cover (b); 5 - collisional granite 300-265 Ma; 6 - dolerites (a) and flood basalt with associated volcanic-sedimentary deposits (b) of the Permian-Triassic trap formation; 7 - MesoCenozoic trough's, suboceanic crust areas (a), and continental rifts (b); 8 - oceanic crust areas and rifts; 1 - major faults (a), including domain boundary (b).

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Figure 16. Paleomagnetic site mean directions in situ (a) and tilt corrected (b). APWP for Kara and it's comparison with Siberia and Baltica APWP's (c). And (d) Paleolatitudinal (top diagram) drift history and latitudinal (middle diagram) and angular (lower diagram) velocity of Kara over geological time (reference location is 79°N 97°E) and comparison with Baltica and Siberia drift and rotation history, after [Metelkin et al., 2005b].

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According to the paleomagnetic data, Siberia was gradually rotated clockwise during the Paleozoic, so that by Triassic time, its eastern margin faced north [Cocks, Torsvik, 2007]. This can be reconciled with the motion along a great circle arc and implies the presence of large-scale strike–slips. The initial paleolatitudinal convergence of Siberia and Kara occurred approximately during the Middle– Late Ordovician, indicating that the two plates were in the same geographic region by that time. However, their strongly divergent APW paths provide unequivocal evidence for their separate existence at that time. Furthermore, paleomagnetic data require a significant relative rotation between Siberia and Kara before the final collision, implying that they were separated by large strike–slips. According to [Torsvik et al., 1996], the APW path for Baltica during the Ordovician to Silurian indicates a northward drift from moderate southerly latitudes to subtropical latitudes. In the Late Silurian, the collision between Baltica and Laurentia caused a change in the drift direction [Torsvik et al., 1996], but by Devonian time, the northerly sense of horizontal motion was restored. At the beginning of the Paleozoic, the northwestern margin of Baltica was rotated towards the Taimyr margin of Siberia. The angular counterclockwise rotation of Baltica from the Cambrian until the middle Devonian was connected to a negligible clockwise rotation of Siberia. The average rotational velocity of Baltica’s motion exceeded 1°/Myr, i.e., was appreciably faster than the rotation of Kara and Siberia [Metelkin et al., 2005b]. The comparatively fast counter-clockwise rotation of Baltica in the Early Paleozoic correlates well with the expansion of Iapetus Ocean and with the postulated occurrence of large-scale transform zones between the approaching Baltica and Siberia plates. This tectonic model implies that Baltica was rotated almost 180° during the Early Paleozoic [Torsvik et al., 1996, Cocks, Torsvik, 2005]. The paleogeographic reconstructions (Fig. 17) comprise the results of integrated paleomagnetic and paleogeographic investigations [Metelkin et al., 2005b]. The Late Cambrian to early Ordovician time are defined by an active spreading between Laurentia on the one hand, and both Baltica and Siberia on the other [Pickering, Smith, 1995, Cocks, Torsvik, 2005]. We suppose a separation of Kara as an individual tarrane has occurred earlier, probably at the stage of Rodinia break-up. Rodinia breakup should be marked by rifting on the continental shelf margins and separation of plates into independent terranes, including small micro-plates such as Kara. Although, there are no paleomagnetic data from Kara terrane that can estimate its position in the structure of Rodinia, we suppose Kara position in Neoproterosoic close to Baltica [Li et al., 2008]. The arrangement of spreading zones that gave rise to the formation of Iapetus also resulted in the counter- clockwise rotation of Baltica and the formation of an extended transform zone on its margins. Cambrian there were at least some trilobite faunal links with other areas [Rushton et al., 2002] identified trilobites from Kara, which provided the faunal correlation at that age level between Siberia, Kara and Baltica. The northward drift of the Kara microcontinent was caused probably by the existence of an extensive system of transform faults between Siberia and Baltica in the Early Paleozoic. The formation of fault system occurred during rifting of these continental plates, with the strike–slip faults resulting from the subsequent relative rotation of the continents. During the Ordovician, Baltica underwent counterclockwise rotation due to rifting, whereas Siberia rotated in the opposite direction. At the same time, the Kara microcontinent drifted northward along a system of dextral strike–slip faults with a simultaneous counterclockwise rotation. Throughout the Middle to Late Ordovician, all three continents (Kara, Baltica and Siberia) were displaced towards the north and the Kara entered the tropics,

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causing a gradual change in sedimentary environment and a concomitant change in the deposition from siliciclastics to carbonate. The Late Ordovician paleolatitudes for Siberia and Kara, on the one hand, and Kara and Baltica, on the other, are practically indistinguishable, providing evidence for the inference of spatial proximity of these two paleobiogeographic provinces. Therefore, the presence in strata on Severnaya Zemlya of Ordovician fauna that are characteristic of both the Siberian and east European paleobiogeographic provinces [Bogolepova et al., 2001] is quite reasonable.

Figure 17. Paleogeographic scheme of drift history of the Kara microcontinent in relation to other continents from Early Paleozoic to time of Pangaea assembled, after [Metelkin et al., 2005b].

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By the end of the Ordovician and the beginning of the Silurian, the extensional tectonic setting was replaced by a compression regime, and oceans separating the three continents began to close. As a result of the tectonic events caused by closure of the ocean between Laurentia and Baltica, the Caledonian collision belt was formed at the end of Silurian [Torsvik et al., 1996]. The paleogeographic position of the continents at this time can be characterized as a subequatorial on the basis of paleomagnetic data [Torsvik et al., 1996; Smethurst et al., 1998; Didenko and Pechersky, 1993 Cocks, Torsvik, 2005, 2007] and carbonate deposits, including “Bahamian” type reefs. By the end of the Silurian, the Kara microcontinent was proximal to the margin of Siberia (their paleolatitudes coincide), but the Late Silurian pole position of Kara differs from that of Siberia. However, Late Paleozoic subduction complexes have not been found on Taimyr, and thus, early collisional events could be connected with transform or strike–slip faults and the discrepancy of paleomagnetic pole positions resulted from relative rotations about local pivots. Nevertheless, the presence of oceanic crust fragments between Siberia and Kara must not be ruled out. Large-scale transform strike–slip shear zones, which brought Kara into juxtaposition with Siberia during the Early Paleozoic, are inferred to have finally resulted in its collision with Siberia and the subsequent formation of nappe-overthrust structures of the Taimyr–Severnaya Zemlya fold belt [Metelkin et al., 2005b]. The final collision of continents occurred in the Late Carboniferous to Permian [Vernikovsky et al., 1995, 1998b, Vernikovsky, 1996, Bogdanov et al., 1998] as the result of strike–slip tectonics [Khramov, Ustritsky, 1990, Metelkin et al., 2005b]. The paleomagnetic evidence proposes that deformation of the Paleozoic margins of Siberia and Kara occurred as the result of differential rotations of these continental blocks.

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4.3. Paleomagnetic Evidence from Siberian Large Igneous Province Siberian Large Igneous Province involves the vast basaltic fields covering Siberian platform, bottom of Kara and Barents seas, and buried flows of West Siberian plate [Dobretsov, 2005]. One of the southern exposition of intraplate magmatism at the Permian/Triassic boundary is a trap formation of Kuznetsk trough [Kutolin, 1963, Kazansky et al., 2005]. The total volume of mantle, volcanic and plutonic rocks according to the different estimations exceeds 16×106 km3 [Dobretsov, 2005]. The traps unconformable overlays Proterozoic and Paleozoic formations where Permian sediments are the youngest. Sidementary layers within the trap formation are limited in number and contain Permian as well as Triassic floras, implies the position of Permian/Triassic boundary within the trap formation [Zolotukhin, Al’mukhamedov, 1988]. The isotope-geochronology determines rather narrow time interval of development of Siberian trap formation -248 - 251 Ma [Dalrymple et al., 1991, Baksi, Farrar, 1991, Renne, Basu, 1991, Claoue-Long et al., 1991; Campbell et al., 1992, Renne et al., 1995, Reichow et al., 2002; Kamo et al., 2003]. A wide distribution of trap formation along with the short time of its development, gives grounds for use of this event as an interregional marker for the correlation in Siberia and adjacent areas.

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Figure 18. Geological sketch map showing the distribution of Permo-Triassic Siberian trap Formation, simplified and modified from [Al’mukhamedov et al., 1999] with paleolatitude directions (a). Legend: 1 - Phanerosoic sedimentary cover; 2 - folded belts and uplifts of Precambrian basement; 3-5 – Trap Formation: 3 – basalt, 4 - basaltic tuff and tuffite, 5 - areas of intrusive trap development; 6 - rift structures of pre-Jurassic basement of West-Siberian plane; 7 - main faults, 8 - Paleolatitudes determined from Permian-Triassic remanence of traps from Kuznetsk trough, stereoplot (b) shows sitemean directions of ChRM of basalt from Kuznetsk trough [Kazansky et al., 2005]; 9 - the same for East Siberia from Paleomagnetic database [McElhinny, Lock, 1996], 10 - Permian-Triassic paleomagnetic directions. The star indicates paleolatitude determined from the core of SG-6 superdeep borehole [Kazansky et al., 2000]. (c) - correlation of magnetic polarity stratigraphy of different trap sequences of Siberia with “Magnetostratigtahpic scale of the USSR” (left) by [Molostovsky, Khramov 1984] and Magnetic polarity time scale (right) by [Opdyke, Channell, 1996]: I – SG-6 superdeep borehole from West Suberian Basin [Kazansky et al., 2000]: II - Noril’sk area , Siberian platform [Lind et al., 1994], III – West Taimyr [Gurevitch et al., 1995], IV - Kuznetsk trough [Kazansky et al., 2005]. Letters at corresponding intervals of magnetic polarity sequences denotes local straigraphic units (formations): ai - Aimal, kr - Korotchaev, hd - Hadyryukh, iv - Ivakino, sd - Sarydasay, lb - Labak, ml - Mal’tsevo. Comment: normal polarity interval (black) in the base of the Kuznetsk trough sequence corresponds to Permian sedimentary rocks [Kazansky et al., 2005].

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Paleomagnetic study of Siberian traps [Lind et al., 1994, Gurevitch et al., 1995, 2004, Westphal et al., 1998, Kravchinsky et al., 2002b, Kazansky et al., 2000, 2005, Veselovsky et al., 2003, Pavlov et al., 2007] revealed that the main stage of magmatic activity fell on 249251 Ma i.e. very close to Permian/Triassic boundary (Fig. 18). It is well known that the whole sequence of trap formation is characterized by normal polarity and only the lower part of Ivakino formation is reversely magnetized [Lind et al., 1994]. The age of Ivakino basalt due to the isotope geochronology is estimated as 248.5 ± 2.4 Ma [Dalrymple et al., 1991]. A close picture is observed in Western Taimyr where the reverse polarity in the deposits of Sarydasay formation in the lower part of section. [Gurevitch et al., 1995]]. The most complete paleomagnetic section of Late Permian - Early Triassic is composed from paleomagnetic study of SG-6 superdeep borehole in Urengoi-Koltogor graben of West Siberian rift system [Westphal et al., 1998, Kazansky et al., 2000]. Due to the paleomagnetic data, the deposition of volcano-sedimentary strata of borehole occurred from Upper Tatarian substage of Late Permian to Olenek stage of Early Triassic (250-245 Ma) [Kazansky et al., 2000]. Reversely magnetized rocks of middle part of Aimal formation are possible analogs of reversely magnetized traps of Kuznetsk trough (Fig. 18). Permian-Triassic boundary according to the paleomagnetic data [Kaзaнckий et al., 2000], is located just in the top of reverse zone in the middle part of Aimal formation. The correlation of magnetic polarity patterns from West Siberia, Norilsk and Kuznetsk trough with Magnetic Polarity Time Scale of the USSR [Molostovsky, Khramov, 1984] and Magnetic Polarity Time Scale by [Opdyke, Channel, 1996] allows to estimate in outline duration and intensity of trap magmatism in Siberia (Fig. 18). In the context of the correlation the trap eruption has initiated synchronously over all regions of Siberia from Kuznetsk trough in the south to Western Taimyr in the north [Al’mukhamedov et al., 1999]. Such a synchronism of magmatic activity over the vast territory can be governed by the influence of mantle superlume [Dobretsov, 2005]. However, the duration of the event and its intensity in each individual region is somewhat different and most likely is determined by a number of local geodynamic conditions. For example, the reversely magnetized succession from Kuznetsk trough which is correlated with the middle part of Aimal formation of West Siberia, to Ivakino formation of Norilsk and to Sarydasay formation of Western Taimyr and correponds to magnetozone R3P of Illavara hyperzone (Fig. 18). On the base of the correlation, we suppose that the development of trap formation in Kuznetsk trough was the most short-term event when compared with the other regions of Siberia. The total duration of the whole trap succesion here is less than 1 Myr. The volcanic activity in West Siberia was much more extended but less intensive than in the other regions. On the base of magnetic polarity pattern of 9 polarity zones from the 1 km basalt succession from SG-6 superdeep, the duration of the trap development ranges up to 5-6 Myr. In the other sections from the north of Siberian platform the quantity of polarity zones is less than three as a rule, however, these sections are much more thicker. The duration of the trap magmatism in the sections is correspondingly less than 2 Myr. Following the correlation, we suggest that all normally magnetized trap successions of Norilsk area and Labak formation of West Taimyr were erupted in the very beginning of Triassic during 2 Myr (Fig. 18). The geological bodies developed during a short time interval over the vast territory is quite suitable for the precise estimation of scale and kinematics of intraplate motions over the territory of Central Asia and Siberia in the end of Paleozoic - beginning of Mesozoic. The Figure 18 shows the distribution of available remanence directions for Late Permian- Early

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Triassic (from IAGA paleomagnetic database [McElhinny, Lock, 1996]). The basic part of this data set is the data from Siberian trap formation. Evidently, the paleolatitudes orientation over Siberian platfrom, Taiymyr and the eastern part of West Siberia (data form SG-6 [Kazansky et al., 2000]) are similar and directed along the present day meridian. In the same time, the paleolatitudes from Kuznetsk trough are oriented at an angle to Siberian ones (Fig. 18). The angular distance between the paleomagnetic pole position from Kuznetsk trough (60.0°N, 172.7°E, A95=4.0) and the other part of Siberian LIP (49.0°N 151.6°E A95=5.0) is 24° ± 7.2° of great circle arc. The most likely explanation of the difference is a strike-slip motion of Kuznetsk trough during or just after the development of trap formation. Probably the strike-slips are precisely the factor controlling the duration and intensity of trap magmatism over the territory. The strike-slip motions were realized along the number of bow-shaped strike-slip zones which were formed even in Early Paleozoic and resulted from “slipping and lagging” and subsequent deformation of the structures of Kuznetsk trough during the motion of Siberian craton with the clockwise rotation [Kazansky et al., 2005]. The deformation of Kuznetsk structures in the end of Paleozoic - beginning of Mesozoic is probably a particular case of global tectonic event for Northern Asia. The strike-slip deformations resulted form the clockwise rotation of Siberian tectonic domain of Eurasian plate can be responsible for the development of submeriadional system of graben structures in the basement of West Siberia that in turn has initiated the development of large MesozoicCenozoic sedimentary basin. The rotation is also determined by a predominant stress environment in southeast of Siberia during Mesozoic realized in repeated mountain buildings and deformations. The same idea was proposed by [Khramov, Radionov, 1980, Bazhenov, Mossakovsky, 1986], who even in the end of the previous century on the base of paleomagnetic data have shown the possible presence of large-scale strike-slip motions between Siberian and European domains of the Eurasian plate at the end of Paleozoic. Kinematics of the process is governed by the clockwise rotation of Siberian part of the Eurasian plate relative to European one. The Euler pole is quite close to our pole for Early Paleozoic. Most likely, the kinematics of Siberian plate preset even in Early Paleozoic still present in general during Late Paleozoic and is responsible for the development of a number of large regional structures at Permian/Triassic boundary. The kinematics was likely continuing in Mesozoic.

5. MESOZOIC INTRAPLATE MOTIONS AND ITS REFLECTS IN THE EURASIA STRUCTURE 5.1. Brief Review The main features of modern structure of North Asia have been formed up to the end of Paleozoic. For Mesozoic time the Siberian part of this plate can be considered as three large tectonic provinces: West Siberian, Central Asian, and Mongolo-Okhotsk [Berzin et al., 1994]. Within the limits of West Siberian tectonic province, the processes of intraplate riftogenesis resulted in evolution of the largest sedimentary basin, whereas in the southern and southwestern territories of Mongolo-Okhotsk tectonic province the development of oceanic basin has been continued and the subduction and collision processes there caused the

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deformation of Transbaikalian continental margin. At the same time the Central Asian province involving the western zone (including Altai-Sayan folded area, Mongolian Altai, Central and Eastern Kazakhstan) and the eastern zone (including Eastern Mongolia, Transbaikalia and southern part of Russian Far East) was developed between Siberian Platform and Mongolo-Okhotsk tectonic province [Belicnenko et al., 1994, Berzin et al., 1994, Gordienko, Kuz’min, 1999]. The assumption of amalgamation of the common Eurasian plate in the end of Palaeozoic became a basic prerequisite to create synthetic APW path for Eurasia as for a single rigid block during Mesozoic and Cenozoic [Besse, Courtillot, 1991, 2002]. The surprising thing is that Mesozoic in Siberia (except Early Triassic) is poorly paleomagneticaly investigated in terms of tectonic problems. No more than 10-15% from available paleomagnetic data set passes the paleomagnetic reliability criteria [Van der Voo, 1990] due to the absence of complete demagnetization procedure, unsatisfactory (according to modern requirements) isolation of magnetization components an lack of paleomagnetic fold tests. Besides, those data have the disadvantage of rather wide age limits for paleomagnetic poles sometimes exceeding 50 (!) Ma. The most part of paleomagnetic investigations of Siberian Mesozoic was oriented on the stratigraphic problems, which do not require a high precision in determination of paleomagnetic pole. Those data, despite to their relatively high reliability are unsuitable to solve the tectonic problems. Thus, the lack of paleomagnetic data suitable for tectonic analysis calls for the additional information from the adjacent regions. So, paleomagnetic poles from China and Europe recalculated for Siberia [Besse, Courtillot, 1991] are used for reconstructions of spatial position of Siberia and Eurasian plate as whole during Mesozoic and Cenozoic. However, even a cursory examination of Mesozoic geological structures and available paleomagnetic data from Siberia, Europe and Central Asia showed the fallacy in such reconstructions [Voronov, 1997, Bazhenov, Mossakovsky, 1986 etc.]. Those data, in total, resulted in the conception that the Eurasia during Mesozoic actually was not a plate with absolutely stable inner structure and gave the backgrounds to suggest the intraplate strike-slip motions both of local tectonic units within Central Asia belt and, possibly, of the whole assemblage of Siberian structures relative to European ones. The assumption of large-scale strike-slip zones set limits on the use of paleomagnetic poles from Europe and China for the paleomagnetic constrains for Siberia as well as for the whole Eurasia during Mesozoic. This section briefly describes our paleomagnetic results from Jurassic and Cretaceous rocks from Siberia necessary for the creation of paleomagnetic backgrounds for the geodynamic reconstructions of Siberia during Mesozoic. The studied objects are located in three different regions of Siberia: Transbaikalia (southern frame of Siberian platform), Minusa trough (south-western frame of Siberian platform) and Verkhoyansk trough (eastern margin of Siberian platform).

5.2. The Mongolo-Okhotsk Tectonic Province (Transbaikalia Region) The Transbaikalia region is dominated by the Late Mesozoic collision between the Mongolia - North China continent and the Siberia - Europe continent as the result of Mongolo-Okhotsk paleoocean closure [Zorin, 1999, Kravchinsky et al., 2002a].

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The products of Mesozoic bimodal volcanism fill a great number of depressions accociated with large-scale strike-slips [Gordienko, Klimuk, 1995]. Evolution of the depressions accompanied with predominantly trachibasaltic volcanism is connected with the mantle plum development and the processes of intracontinental rifting [Gordienko, Kuz’min, 1999] in the rear of active continental margin of Californian type [Gordienko et al., 2000] at the stage of ocean closure [Zorin, 1999]. The paleomagnetic sampling locations are shown in Figure 19. Tugnui volcanic province is one of the largest Mesozoic intracontinental rift depressions in Transbaikalia. The depression was formed as a result of intracontinental strike-slip motion along Tugnui-Konda fault zone. The bimodal volcanic and terrigenous series from Early Permian to Early Cretaceous age are widespread in the province. But the Late Jurassic epoch was a time of main volcanic activity [Gordienko, Klimuk, 1995]. The Ithetuy formation consists of subalcaline extrusive units interbedded with the beds of conglomerate, sandstone and siltstone. The Upper Jurassic (from Oxfordian to Kimmeridgian) age is based on K-Ar (150 ± 5 Ma) and Rb-Sr (153 ± 2 Ma) isotopic data [Gordienko et al., 1997, Gordienko, Klimuk, 1995]. Paleomagnetic study of trachibasalt allowed to isolate a stable ChRM direction (Table 6, Fig. 20). The ancient nature of the magnetization is confirmed by the positive paleomagnetic field tests [Metelkin, et al, 2007b]. Stable ChRM components in the conglomerate pebbles are randomly distributed: Robs. = 0.292 less than Rcrit. = 0.388, k=1.3, for n=17. The reversal test [McFadden and McElhinny, 1990] is statistically significant in classification ‘‘C’’ (the angular distance γ=9.2º is less than the critical angle γc=12.3º after tilt correction). Application of the fold test [McElhinny, 1964] for all site-mean directions from Tugnuy province gives a positive result: ks/kg=24.8 is higher than the critical value at the 99% confidence level (3.7) for n=8. The fold test by [Watson, Enkin, 1993] gives an optimum degree of untilting at 112.2% with 95% confidence limits at 104.6 and 119.6%. The direction–correction tilt test [Enkin, 2003] also gives the positive result DC Slope: 1.122 ± 0.142. The Margintui volcanic province is located between Dhida, Tchikoy and Khilok rivers of Transbaikalia (Fig. 19). Predominantly alkaline and subalcaline trachybasaltic lava fields with a several central type volcano structures are recognized in this province [Zhamoitsina, 1997]. The age of Margintuy basalt is based on K-Ar (156 ± 6 Ma) data and is close to OxfordianKimmeridgian boundary [Gordienko, Zhamoitsina, 1995]. These rocks are very like to the trachybasalt of Ithetuy formation by the chemical composition and structural position and can be correlated with Late Jurassic bimodal volcanic activity of itracontinental rifts evidence on the southern frame of Siberian platform. We have investigated one of these volcano structures named Dulan-Khara [Metelkin et al, 2007b]. The direction of recognized ChRM component here is not statistically different from those in basalt from Tugnui depression (Table 6, Fig. 20). But, due to monocline dipping of beds, the fold test for Margintui site-mean direction is inconclusive. The Maly Chamardaban volcanic province is located to the south from Lake Baikal along the left bank of the Dzhida river (Fig. 19). Late Jurassic bimodal volcanic rocks of the Ithetuy formation are widespread in the province. Ichetuy formation consists of trachybasalt, trachyte, trachyandesite with the sporadic thin layers of tuff and terrigenous rocks. The trachybasalt dominate here and formseries of lava flows from 1.5 to 10 more rarely to 30 m thick. The rarity of tuff and many interbedded horizons of thick lava flows indicate intensive interstitial eruption process during Late Jurassic [Litvinovsky et al., 1996]. The age of the Ichetuy

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trachybasalt based on Rb-Sr and K-Ar isotopic data [158 ± 4 Ma] is close to OxfordianKimmeridgian boundary [Shadaev et al., 1992]. The mean site ChRM direction (Fig. 21) of studied trachybasalt [Metelkin et al, 2007b] slightly differs from those in the basalt form Tugnuy and Margintui depression (Table 6). The fold test for sites of Maly Chamardaban province is inconclusive, due to the monocline dipping. We suggest the distinctions between paleomagnetic directions reflect one of following reasons: i] small-scale local rotation of investigated blocks during Cenozoic stage of deformation; ii] large secular variations of ancient geomagnetic field; iii] lack of correction for slope of volcanic cone.

Figure 19. Schematic structure of the Late Mesozoic-Cenozoic West Transbaikalian rift region, modified from [Yarmolyuk et al., 1998]). Legend: 1, 2 — depressions and grabens filled up chiefly by volcanic (1) and terrigenous (2) rocks; 3 — rift zone area; 4 — rift zone frame. Depressions (volcanic province) lettered as follows: B - Borgoi, ChKh - Chikoi-Khilok, GO - Gusinoe Ozero, M — Mogzon, MKh — Maly Khamar-Daban, MT — Margintui, T — Tugnui and U - Uda.

The combined analysis of Jurassic site-mean directions from the three volcanic provinces confirms the primary nature of magnetization. The remanence shows a significant increase in grouping upon tilt correction which is statistically significant (ks/kg=41.3/8.2>Fc at 99% confidence limit for n=18). The fold test by [Watson, Enkin, 1993] is positive as well: an optimum degree of untilting is achieved at 95.0% with 95% confidence limits at 90.2% and 100.4%. The mean paleomagnetic pole of 63.6°N, 166.8°E is calculated as an average of virtual paleomagnetic poles (VGP) from each studied locations coincide 150-160 Ma pole defined by [Kravchinsky et al., 2002a] for Badin formation of Mogzon depression (Transbaikalia). Such a good agreement is additional evidence of Late Jurassic age of the remanence.

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Figure 20. Typical orthogonal plots and NRM decay plots from stepwise thermal demagnetization of the Sukhara trachybasalt (Tugnui province), plots (a) and of Dulan-Khara trachybasalt (Margintui province), plots (b). After [Metelkin et al., 2007b]

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Table 6. Paleomagnetic directions from Late Jurassic basalt of Transbaikalia Section, rock, sampling site

n

In situ D (º) I (º)

Tilt corrected D (º) I (º)

39.3 30.2 22.8 357.7 16.0 34.1 191.2 12.9 24.6

43.5 28.7 54.6 12.5 60.9 42.3 208.9 17.9

62.3 65.7 76.2 80.0 77.8 73.9 -70.2 79.0

36.9

73.6

52.1 16.9 17.0 15.3 346.0 46.8

74.6 75.2 67.6 69.4 71.1 68.1

22.1

72.2

k

α95

36.0 30.4 29.2 201.4 191.4 191.4 29.5 72.4 4.4 109.3

8.7 10.2 12.6 2.7 3.5 3.5 11.3 5.4 29.7 5.3

129.9 110.5 266.2 163.5 204.1 92.4 97.5 98.4

5.9 6.4 3.4 6.0 4.7 8.0 6.8 6.8

Tugnui VTS Sukhara, trachybasalt, 04s03 Sukhara, trachybasalt, 04s04 Sukhara, trachybasalt, 04s05 Sukhara, trachydolerites, 04s06 Sukhara, trachydolerites, 04s08 Sukhara, trachybasalt, 04s09 Butsygyr, trachydolerites, 04s10 Butsygyr, trachydolerites, 04s11

9 8 6 15 10 10 7 11

Mean for depression

8/8

-22.4 -17.9 59.9 60.5 47.9 34.1 -84.9 59.1 40.9

Margintui VTS Dulan-Khara, basalt, 00s14 Dulan-Khara, basalt, 00s15 Dulan-Khara, basalt, 00s16 Dulan-Khara, basalt, 00s17 Dulan-Khara, basalt, 00s18 Dulan-Khara, basalt, 00s19 Mean for depression

6 6 8 5 6 5 6/6

55.1 33.5 29.1 28.8 10.1 51.8 35.4

64.7 66.9 59.5 61.5 66.9 58.5 63.8

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Maly Khamar Daban VTS Armak, basalt, 01s10b Armak, basalt, 01s10c Armak, basalt, 01s10d Armak, basalt, 01s10e

Mean for depression

11 13 8

58.6 57.7 45.8

63.2 64.8 64.5

78.0 78.5 69.9

53.7 55.4 57.3 60.

50.3 113.9 75.8

6.5 3.9 6.4

12

53.0 53.9

69.7 65.6

79.4

5

76.5

56.8

37.3 460.0 462.3

7.2 4.3 4.3

4/4

Comment: n - number of samples used in statistics (for depression means: numerator -number of sites used in statistics, denominator - number of studied sites); D - paleomagnetic declination; I – paleomagnetic inclination, k – precision parameter (Fisher statistics); а95 – radius of 95% confidence limit. Coordinate systems: for site means tilt corrected only, for depression means upper line - in situ system; lower line - tilt corrected.

The Early Cretaceous rocks of Khilok formation make up the Chikoi-Khilok depression south from Ulan-Ude in the basin of Chikoi and Khilok rivers (Fig. 19). The volcanic rocks are exposed along the margins of depression (Fig. 22) and represent series of less then 15 m thick trachybasaltic lava flows divided by layers of sandstone and conglomerate [Gordienko et al., 1999]. The Ar-Ar geochronology indicates that the most volcanism took place during a short period from 122 up to 113 Ma [Gordienko et al., 1999]. Well-defined ChRM directions (Fig. 22) both of normal and reversal polarity were isolated during the paleomagnetic study

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[Metelkin et al, 2003]. The magnetic polarity pattern of Khilok formation is in a good agreement with age estimations provided by Ar-Ar dating and supports the suggestion of an earlier extrusion of shoshonite lava [Gordienko et al., 1999]. Due to 39Ar/40Ar dating the time of shoshonite volcanism is 122 ± 0.6 Ma, while the paleomagnetic study documents only reverse polarity in shoshonite. According to GPTS [Opdyke, Channel, 1996] the Early Cretaceous is characterized by a predominant normal polarity (Chron C34 – AptianSantonian). The first short reverse polarity interval (CM0) appears between 120 and 121 Ma (Aptian/Barremian boundary). The trachybasalt are somewhat younger 115.5±1.2 Ma and are characterized by the normal polarity. The corresponding polarity-means differ by 178.0° (γ=2.0° which is less than critical angle γc=12.3°) rendering the reversal test positive with “C” classification by [McFadden, McElhinny, 1990]. The Chikoi-Khilok locality mean direction on the basis of 13 sites (Table 7) passes the positive fold test [McElhinny, 1964] at 95% confidence level (ks/kg=2.10>Fc=1.98). The fold test simulation using [Watson, Enkin, 1993] method for all site-mean directons from Chikoi-Khilok province gives an optimum degree of untilting close to 100% (82.5%±12.7%) and indicates that the remanence is pre-tilting. The direction-correction fold test by [Enkin, 2003] gives a completely positive result DC Slope: 0.825 ± 0.345. As well, the absence of regional overprint of Khilok formation is proved by the positive conglomerate test. The population of remanence directions from 28 pebbles have a precision parameter is quite low k=1.2. The normalized vector resultant of 0.226 is much less than the critical value of 0.301 [Marida, 1972].

Figure 21. Typical orthogonal diagrams and NRM decay plots from results of stepwise thermal demagnetization of Armak trachybasalt (Maly Khamardaban volcanic province). After [Metelkin et al., 2007b]

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Figure 22. Geological scheme (a) of Thikoi-Khilok depression, modified from [Gordienko et al., 1999]. Legend: 1 - Quaternary deposits; 2 – basalt of Itchetuy formation (J3); 3 – volcano-sedimentary rocks of Khilok Formation (K1); 4 – sedimentary and coal-bearing deposits of Gusinoeozero series (K1); 5 – Cenozoic basalt; 6 – Proterozoic-Paleozoic complexes in the basement and frame of the depression; 7 – faults; 8 – unconformity boundaries; 9 – paleomagnetic sampling locations: 1 – Beregovaya, 2 – Bichura, 3 – Mateta, 4 – Potanino. Typical orthogonal plots of stepwise demagnetization of basalt from Thikoi-Khilok depression with corresponding k(T) decay plots (b), after [Metelkin et al., 2003].

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206

Table 7. Paleomagnetic directions from Early Cretaceous volcanic and sedimentary rocks of Transbaikalia Section, rock, sampling point

n

In situ D (º) I (º)

Tilt corrected D (º) I (º)

300 310 312 314 323 91.7 13.6 331.6 349.9 198.9 104.7 22.7 169.2 124.1

204 218 226 230 222 44.1 31.9 30.8 170 184 32 4.1 23.6

-55.9 -61.5 -62.9 -63.7 -68.4 59.6 53.9 60.3 -78.3 -62.6 69.9 65.9 83.4

30

65.9

14.5 12.3 12 7.9 29.2 18.3 333.4

67.1 65.4 75 65.1 71.5 74.8 74.7

10.7

71.1

52.1 223 241.8 232.4 200

68 -52 -66.6 -65.2 -64.1

45.2

63.9

k

α95

30.4 529.7 392.1 652 16.8 159.1 35.5 38.8 328.7 92.1 63.7 67.7 106.9 26.7 56.1

8.9 2.1 2.8 3.6 19.2 4.8 11.4 9 3.7 5.8 6.1 8.2 5 8.2 5.6

57.9 67.3 171.3 76.5 86.2 217.6 99.4 68.7 138.5

6.4 6.8 3.7 8.8 6 4.1 4.6 7.3 5.1

37.6 213.3 42.4 217.2 29.6 74.3 76.2

8.5 3.8 10.4 3.5 14.3 8.8 8.9

Chikoi-Khilok Depression Beregovaya, sandstone, 00-26b Beregovaya, shoshonite, 00-07 Beregovaya, shoshonite, 00-08 Beregovaya, shoshonite, 01-26а Beregovaya, shoshonite, 01-26с Bichura, trachybasalt, 00-09 Bichura, trachybasalt, 00-10 Bichura, trachybasalt, 00-11 Maleta, trachybasalt, 01-14а Maleta, trachybasalt, 01-14b Potanino, trachybasalt, 01-15а Potanino, trachybasalt, 01-15b Potanino, trachybasalt, 01-15c Mean for depression

10 10 8 4 5 7 6 8 6 8 10 6 9 13/13

-70.2 -62.4 -58.4 -56.8 -59.2 86.2 81.2 86.1 -86.7 -76.7 79.2 85.6 75.8 78.1

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Borgoi Depression Lower, trachybasalt, 01s01 Lower, trachybasalt, 01x01 Upper, trachybasalt, 01s03 Upper, trachybasalt, 01x03 Dabkhor, teschenite, 01s02 Dabkhor, teschenite, 01x02 Guntui, teschenite, 01s04

10 8 10 5 8 7 11

Mean for depression

7/7

0.1 359.4 337 345.1 9.3 356.4 339.7 352.8

54.3 52.5 65.8 56.6 70.1 72.1 70.1 63.5

Uda Depression Amgalanta, trachydolerites, 01x32 Amgalanta, trachybasalt, 01x33 Ashanga, trachybasalt, 01x34a Ashanga, trachybasalt, 01x34b Bulym, trachybasalt, 01x35 Mean for depression

9 8 6 9 5 5/5

10.7 203 219.8 210.7 181.8 19.8

73.1 -57.2 -72.3 -69.8 -60.8 67.2

Comment: n - number of samples used in statistics (for depression means: numerator -number of sites used in statistics, denominator - number of studied sites); D - paleomagnetic declination; I – paleomagnetic inclination, k – precision parameter (Fisher statistics); а95 – radius of 95% confidence limit. Coordinate systems: for site means tilt corrected only, for depression means upper line - in situ system; lower line - tilt corrected.

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Figure 23. Geological scheme (a) of Borgoi depression, modified from [Vorontsov et al., 1997]) Legend: 1 – subvolcanic techenite bodies: DKh – Dabkhor Lopolith; laccoliths: Gn – Guntui, C – Central, Bl – Belozero, Bu – Bayanundur, DKhN – Northern Dabkhor; 2 – basaltoid of Khilok Formation (K1), 3 – sandstone, 4 – rhyolite body, 5 – pre-Mesozoic basement, 6 – Quaternary deposits, 7 – paleomagnetic sampling locations: 1 – lower section, 2 – upper section, 3 – Dabkhor; 4 – Guntui. Typical orthogonal plots of stepwise demagnetization of basalt from Borgoi depression with corresponding k(T) decay plots (b), aftre [Metelkin et al., 2004b]

The Borgoi depression is located on the left riverside of the Dzhida basin, about 60 km to the west from Chikoi-Khilok and Tugnui volcanic province (Fig. 19). This depression has a brachysyncline structure and is filled by Early Cretaceous volcano-sedimentary deposits that referred to Khilok formation (Fig. 23). Two types of volcanic rocks are recognized within the

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depression: thin basaltic and trachybasaltic lava flows interbeded with the sediments and intrusions (mainly laccoliths, dikes and sills are also present). The K-Ar geochronology suggests that the volcanic activity in the Borgoi depression took place between 102 and 136 Ma comprising two stages with the periods of active volcanism and prolonged hiatuses in activity [Vorontsov et al., 1997]. The earliest extrusion is presented by basalt with an age of 136-132 Ma. The second stage of volcanism is dated as 110 - 120 Ma and is presented by the trachybasalt-teschenite association that includes thin lava flows and subvolcanic intrusions [Vorontsov et al., 1997]. We have studied volcanic rocks of both stages [Metelkin et al, 2004b]. Direction of ChRM does not differ between studied trachybasaltic lava flows and teschenite intrusions (Fig. 23, Table 7). Despite the approximately monoclinal nature of the lava flows at these localities, and absence of variations in bedding attitudes for teshenites of laccoliths, the site-mean directions show their best grouping in stratigraphic coordinates upon incremental unfolding and application of the direction-correction tilt test [Enkin, 2003] gives a positive result (DC Slope: 1.169 ± 0.898), thus supporting the ancient age of remanence, most likely close to 120 Ma. The Uda volcanic province is located at 150 km eastward from Ulan-Ude along the right bank of the Uda river (Fig. 19). The Early Cretaceous volcanic rocks are exposed as small fragments along Uda riverside (Fig. 24). Generally, the sections are composed of a succession of thin trachybasaltic lava flows but sometimes are presented by the sedimentary rocks inerbedded with the sporadic lava flows or sill-like bodies. The geochemical investigations and K-Ar geochronology from this area suggest that the trachybasalt were formed about 131126 Ma [Ivanov et al., 1995] and probably correspond to Khilok formation. Four of five studied trachybasaltic lava flows show reversed ChRM direction and one is normal (Table 7). The vector population used for the reversal test [McFadden, McElhinny, 1990] includes 9 samples of the normal polarity and 28 samples of the reversal polarity. The angular distance γ=6.5 is less than the critical value γc=9.7 that means the test is positive with “B” classification. Summarizing of paleomagnetic data for all Early Cretaceous sites from Chikoi-Khilok, Borgoi and Uda volcanic provinces testifies prefolding origin of ChRM. The mean directions for each province show a significant increase in grouping upon tilt correction which is statistically significant (ks/kg=116.4/18.2>Fc at 99% confidence level for n=3). Application of the fold test [Watson, Enkin, 1993] for the site-mean directons from all provinces gives an optimum degree of untilting close to 100% (90.1%±5.7%) and indicates that the remanence is pre-tilting. Altogether there are fourteen sites (individual basaltic lava flows) where the normal polarity was observed and ten sites demonstrate the reversal polarity. These with a positive reversal test [McFadden, McElhinny 1990] in classification “B” (the angular distance γ=6.6 is less than the critical angle γc=7.7) after tilt correction, suggests that the geomagnetic secular variation has been averaged sufficiently. Mean paleomagnetic pole of 72.3°N, 186.4°E A95=6.0 is calculated by averaging of individual site VGPs and correspods to ~ 120 Ma. We believe that this pole can be used for the reconstruction of Siberian spatial position as whole because the basement of Transbaikalian frame where studied depressions are located, has been finished up to the end of Silurian - beggining of Devonian and after this the region was developed as a marginal part of Siberian plate [Gordienko, Kuz’min, 1999, Zorin, 1999].

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Figure 24. Geological scheme of Uda depression modifeid from [Metelkin et al., 2004b] (a) Legend: 1 - Quaternary deposits; 2 – volcano-sedimentary rocks of Khilok formation (K1); 3 - preMesozoic basement; 4 - – paleomagnetic sampling locations: 1 – Amgalanta 01х32, 2 - Amgalanta 01х33, 3 – Ashanga 01х34а, 4 - Ashanga 01х34b, Bulym 01х35 Typical orthogonal plots of stepwise demagnetization of basalt from (b) after [Metelkin, et al, 2004b].

5.3. Implication of Trasbaikalia Paleomagnetic Evidence to Tectonic of Mongolo-Okhotsk Ocean Cloused Mesozoic paleomagnetic poles from Transbaikalia statistically differ from the same-age paleomagnetic poles from Europe and SE Asia (Table 8, Fig. 25). Thus, on the assumption of Late Jurassic paleomagnetic pole positions from North China and Mongolia [Gilder et al., 1997, Zhao et al., 1990], the discrepancy between the expected and observed paleomagnetic directions for Siberia exceeds 10° in inclination and more than 20° in declination. Jurassic paleolatitude differences for Northern China and Mongolia from the one side and Siberia from the other one suggest the existence of open oceanic basin about 1000 km in width between these tectonic units. To achieve the modern tectonic configuration of the region, it needs at least 6.8° (~ 750 km) block motion along the latitude. Such a large distance between the tectonic units can be attributed to the deformation with thicknessing of continental crust

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as the result of collision after the closure of Mongolo-Okhotsk ocean, or this difference more likely reflects the width of this ocean. The second assumption seems to be more realistic. The closure process and subsequent collision can result in the sufficient local rotations of heterogeneous tectonic units within the interaction zone of continental domains [Kravchinsky et al., 2002a]. However, the kinematic parameters (Table 8) testify the presence of regional large-scale motions reflecting the strike-slips between the main continental domains of Eurasia. On the base of available data we suggest that the convergence between SE Asia blocks (N.China, Monholia et al.) and Siberia during Mesozoic is situated by clockwise rotation of Siberia through 10° to 30° (Table 8). As well, the indicated rotation is interpolated to Northern Asia as whole and suggested by comparison of Mesozoic paleomagetic poles frpm Siberia and Europe. The angular displacement R (rotation) of Siberia relative to Europe is 21.4±14.5 and is quite close to the rotation of Siberia relative to SE Asia blocks (Table 8, Fig. 25). Most likely that both rotations are reflecting a single global tectonics. The geological implication of this tectonics in Transbaikalia appears to be intensive bimodal volcanism, which is abundant within the depressions of pull-apart type.

Figure 25. Mesozoic poles from Transbaikalia in comparison with APWP for Eurasia (European tectonic domain of Eurasia, after [Besse, Courtillot, 2002]) and APWP for North China block (after [Zhao et al., 1996; Gilder, Courtillot 1997]). Thin dotted curves are the small circles passing through Siberian and European poles with the same age and centered on Euler Pole (see Table 8). Stereoplots (below) show the distribution of site-mean directions of ChRM for 120 Ma (Table 7) and 155 Ma (Table 6) pole.

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Thus, available paleomagnetic data suggest that during the end of Jurassic the MongoloOkhotsk ocean was not completely closed (Fig. 26). Gradual closing of the ocean was propagating from the west to the east [Kravchinsky et al., 2002a] under the sufficient sinistral strike-slip conditions between Siberian and European tectonic domains of Eurasia plate, which was caused by a clockwise rotation of Siberia (Fig. 26). Table 8. Correlation of Late Mesozoic paleomagnetic directions and pole positions from Siberia with expected directions and poles recalculated from Europe and Asia and kinematic parameters of Siberian drift and rotation relative to main tectonic units of Eurasia Block

Pole

Age, Ma

Lat

Long

A95

References

Plat

D

I

53.4

12.1

69.6

α95

R

F

Late Cretaceous SIB

75

82.2

188.5

6.1

Metelkin et al., 2007c

3.9

EUR

75

81.3

188.6

7.2

Besse, Courtillot, 2002

52.9

14.3

69.3

4.6

1.4±11.5

-0.3±6.9

NCB

K2

81.1

194.0

11

Zhao et al., 1996

52.0

14.1

68.7

7.2

1.2±15.3

-1.1±8.1

50.2

28.9

67.4

3.8

Expected for Siberia at 55.0°N / 90.2°E

Early Cretaceous SIB

120

72.3

186.4

6.0

Metelkin et al., 2004b

EUR

120

78.2

189.4

2.4

Besse, Courtillot, 2002

50.7

18.7

67.7

1.6

9.4±7.5

0.1±4.8

NCB

К1

78.6

202.6

6.2

Gilder, Courtillot. 1997

48.2

17.2

65.9

4.2

10.9±9.7

-2.4±6.0

MON

K1-2

77.3

215.2

7.5

Hankard et al. 2005

45.3

17.3

63.6

5.3

10.8±10.4 -5.2±6.6

63.6

166.8

8.5

Metelkin et al., 2007b

56.5

44.4

71.7

5.2

7.0

Kravchinsky 2002a

Expected for Siberia at 50.6°N / 107°E

Late Jurassic

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SIB

155

Expected for Siberia at 50.9°N / 106.5°E SIB

155

64.4

161.0

et

al.,

59.1

42.9

73.3

4.1

1.2±15.1

2.6±8.0

EUR

150

75.0

159.9

6.6

Besse, Courtillot, 2002

57.9

23.0

72.6

3.9

21.4±14.5

1.3±7.9

NCB

J3

74.4

222.8

5.9

Gilder, Courtillot. 1997

42.2

19.0

61.2

4.4

25.4±12.7

-14.4±7.6

MON

J3

68.5

231.6

9.5

Zhao et al., 1990

36.1

21.8

55.6

7.9

22.7±14.2

-20.5±9.4

Comment:. VGP — paleomagnetic pole: Lat/Long and α95 — geographic latitude/longitude and 95% confidence oval; Plat — paleolatitude, D — declination, I — inclination, α95 — 95% confidence oval, R and F — quantitative characteristics of motion of Siberia relative to a corresponding tectonic block in degrees (calculated by an algorithm used in PMSGC v.4.1 program (Enkin, 1994)): R — rotation angle: plus - clockwise, and minus - counterclockwise. F — latitudinal displacement (along longitude poleward): plus - northward, and minus - southward.

The proposed model suggests the presence of large scale strike-slip zones along the periphery of Siberia, most likely as the result of reactivation of more ancient sutures within the structure of Central Asia belt. It should be noted, that a similar tectonics for Central Asia was reconstructed for Permian/Triassic boundary [Kazansky et al., 2005] and the scale of the motions decreased in time step-by-step. Thus, the difference in latitudes and meridional orientation between Siberian and European provinces for Permian/Triassic can be estimated

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no less that as 30° [Kazansky et al, 2005] whereas for Late Jurassic it is about 20° and for Early Cretaceous only 9.4°±7.5° (Table 8, Fig. 25). Early Cretatceous paleomagnetic pole from Siberia almost coincide to the referent poles for Europe as well as for SE Asia, thus testifies the complete closure of Mongolo-Okhotsk oceanic basin up to this time (Fig. 26).

Figure 26. Paleotectonic reconstruction for the time of Mongolo-Okhotsk ocean closure, after [Metelkin et al., 2004b]. SIB – Siberian Domain, EUR – European Domain , КAZ – Kazakhstan Domain, NA - North America continent , NSB – North China block , SCB – South China block, ТAR - Tarim block, MON Mongolia block, OChB - Okhotsk - Chukcha volcanic belt, UAB - Upper Amurian volcanic belt, МОS - Mongolo-Okhotsk Suture, TRZ – Transbaikalia rift-related zone, Rectangles attributary show locations of Mesozoic grabens and depressions.

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5.4. The Late Mesozoic Intraplate Magmatism of Minusa Depression (Central Asian Tectonic Province) At the end of Cretaceous, we assume some stabilization of tectonics related to the intraplate motions. This testified by our paleomagnetic data from Minusa depression located southwestward from Siberian craton (Fig. 9). A specific province of alkaline basaltic magmatism here is represented by the necks and dikes with abundant xenoliths of mantle material [Golovin et al, 2000]. In some sense this makes the intrusions more closely resemble to volcanic pipes or diatrems. The host rocks for the diatrems are volcano-sedimatary rocks of Devonian age overlaying accretionary-collisiona structure of the depression basement that was formed during the closure of Paleoasian ocean during Early Paleozoic [Berzin, Kungurtsev, 1996]. Late Cretaceous diatrems are distributed as the close groups of two or more individual bodies accompanied with dolertie dikes (Fig. 27). According to their chemical composition, the basalt of intrusions is correlated with intracontinental type [Malkovetz, 2001]. 39Ar/40Ar dating determines extrusion as a very short event at 77 ± 5 Ma [Bragin et al., 1999, Malkovetz, 2001]. We have studied 16 intrusions including 13 diatrems and 3 associated dikes of basaltic composition (Table 9). The results of rock- and paleomagnetic studies as well reversal and baked contact tests prove that stable remanence corresponding to intrusions cooling time [Metelkin et al., 2007c].

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Table 9. Paleomagnetic directions form Late Cretaceous intrusions of Minusa trough Diatreme Tri Brata Bezymyannaya Intikol’ Tergeshskaya Krasnoozerskaya Satellit Sestra Kongarovskaya Borazhul’skaya Chabaldak Bele Tochilnaya Tochilnaya 2 Dike 1 Dike 2 dolerite baked contact rocks Dike 3

Age, Ma 75±2.4

77±1.9 77±3.9 74±2 75±6.2 74±5.5 77±5 79±2 76±1

n 8 9 9 16 30 19 19 29 20 9 10 21 13 17 13 7 6 7

D (º) 5.4 14.8 6.5 15.7 7.1 17.4 180.1 183.7 164.4 178.5 203.4 191.6 205.3 196.7 213.2 208.1 218.4 228.5

I (º) 72.6 78.9 67.2 71.0 72.0 66.1 -62.5 -59.4 -64.4 -68.8 -60.5 -69.6 -58.5 -76.8 -65.9 -67.6 -63.7 -81.6

k 51.4 41.3 63.7 42.8 42.1 56.6 67.9 99.1 51.3 53.5 42.4 113.2 44.3 61.1 48.7 55.1 40.6 159.1

α95 7.8 8.1 6.5 5.7 4.1 4.5 4.1 2.7 4.6 7.1 7.5 3.0 6.3 4.6 6.0 8.2 10.6 4.8

Comment: n - number of individual samples used in statistics; D - paleomagnetic declination; I – paleomagnetic inclination, k – precision parameter (Fisher statistics); а95 – radius of 95% confidence limit. , Age -39Ar/40Ar age according to [Bragin et al., 1999; Mal’kovets, 2001]

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Figure 27. Geographical location and geologic structure of Minusa Trough after [Metelkin et al., 2007c] Legend: 1 — Late Cretaceous diatremes and dolerite dikes, 2 — Quaternary deposits, 3 — Visean deposits, predominantly greenish-gray and yellow-gray sandstone, 4 — Tournaisian limestone, sandstone, siltstone, and mudstone, 5 — Famennian red sandstone, siltstone and mudstone, 6 — Frasnian variegated and red mudstone, siltstone, and sandstone, 7 — Givetian limestone, dolomite, gypsum, gray and yellow mudstone, and marl, 8 — undifferentiated volcanogenic complex of Lower and Middle Devonian: porphyrites, tuffs, conglomerates with layers of sandstone and siltstones. Below shown representative orthogonal plots of thermal demagnetization of basalt from different bodies, for details see [Metelkin et al., 2007c]

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215

Figure 28. Distribution of stable remanence in Late Cretaceous intrusions of Minusa trough (see Table 9). Below shown correlation of 39Ar/40Ar dated [Bragin et al., 1999; Mal’kovets, 2001] magnetic polarity intervals (see table) with Magnetic Polarity Time scale [Gradstein et al., 1995] Black indicates normal polarity, white - reversed; vertical segments denote confidence limits for 39Ar/40Ar dates.

Due to the explosive character of extrusion of the diatremes there are some problems in performance of the baked contact test. Exocontact zones are represented by eruptive breccia and generally are poorly exposed. However, the contacts zones of small dikes with Devonian sedimentary rocks sometimes are quite suitable for paleomagnetic sampling. We have studied exocontact of the dike located in 4 km northward of Krasnozoyrskaya diatrme (Fig. 27). The host sedimentary rocks are baked and changed their color. The mean directions of stable remanence in dolerite from the dike and backed rocks from the contact zone do not statistically differ (Table 9): the angular deviation of γ=5.8° is less the critical value γc=12°, while the remanence in the host rocks far from the contact are sufficiently different [Kazansky et al, 1996, Metelkin et al, 2007c]. Normal polarity was recognized in 6 and reversed polarity in 9 diatrems (Table 9, Fig. 28). The corresponding polarity-means differ by 176.2° (γ=3.8° that is less than critical

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angle γc=6.8°) rendering the reversal test positive with “B” classification [McFadden, McElhinny, 1990]. The normally magnetized intrusions most likely is attributed to C33 Chrone (79-75 Ma). The intrusions with the reversed polarity correspond to an age of 74 Ma ago (i.e. Kongarovo, Sestra and porobably Tochilnaya diatrems), which is correlated to a short reverse polarity interval within Chron C32 or to Chron C33 in the beggining of Campanian stage (i.e. Bele and probably Boradzhul diatrems). In the last case the age of those diatrems cannot be younger that 79 Ma (Fig. 28). Paleomagnetic pole of 82.8°N, 188.5°E, A95=6.1 within the confidence limits does not differ from Late Cretaceous pole of European APWP (Fig. 25). It means, that intraplate motions and corresponding crustal deformations in Central Asia, which we suggest for Mesozoic have already finished up to the end of Cretaceous, or most plausibly their scales are rather small, less than the accuracy of paleomagnetic method.

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5.5. Lena Region of Siberian Platform (Verkhoyansk Trough) and Summary of Mesozoic Tectonic and Paleomagnetic Evidence for Siberia The third object of our paleomagnetic study is located in the lower and middle course of the Lena river, in the limits of border parts of Vilyui and Verkhoyansk troughs at the east margin of Siberian platform (Fig. 29). We have studied sedimentary succession comprised of 9 stratigraphic units (formations) from Middle Jurassic to Early Cretaceous [Metelkin et al, 2008]. The detailed stratigraphy allows define the age of studied successions up to the stratigraphic stage [Parfenov, Kuz’min 2001]. The deformations of Late Mesozoic strata filling the Verkhoyansk trough reflects the youngest stage of East Siberia collision events linking to overthrusting of Verkhoyansk orogen up to the end of Cretaceous [Parfenov et al., 1995]. As a result of this deformation several large flat-topped structures with the steep attitudes up to 40° and more were formed (i.e. Chekurovka anticline where we have sampled the main part of Late Mesozoic section). Stepwise thermal demagnetization of terrigenous rocks from Verkhoyansk isolates stable ChRM directions that are characterized by a steep (from 70° to 85°) inclinations typical for Jurassic and Cretaceous of Siberia (Fig 29). However, ChRM declination in Early Cretaceous sandstone is about 70°, while in Middle Jurassic up to 140° (Table 10). The site-mean direction on the basis of 11 sites of Early Cretaceous rocks passes the positive fold test [McElhinny, 1964] at 99% confidence level (ks/kg=5.90>Fc=2.94). The fold test simulation using [Watson, Enkin, 1993] method gives an optimum degree of untilting close to 100% (82.8%±6.0%) and indicates that remanence is pre-tilting. The directioncorrection fold test by [Enkin, 2003] gives a completely positive result (DC Slope: 0.825 ± 0.197). Application of the fold test [McElhinny, 1964] for the Middle Jurassic site-mean directions gives a positive result also: ks/kg=116.8 is much higher than the critical value at the 99% confidence level for n=4. The fold test by [Watson, Enkin, 1993] gives an optimum degree of untilting at 95.6% with 95% confidence limits at 102.1 and 89.6%. The direction– correction tilt test [Enkin, 2003] also gives the positive result DC Slope: 0.958 ± 0.164.

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Table 10. Paleomagnetic directions and pole positions from Late Mesozoic deposits of Verkhoyansk trough (Lena River). Place, sampling site, Formation

Age (~ Ma)

n

In situ D (º) I (º)

Tilt corrected D (º) I (º)

9

333.7

82.0

57.5

9

40.5

87.9

7

74.5

10

VGP Long dp/dm

k

α95

76.5

61.8

6.6

68.0

204.3

12.2/11.3

67.9

80.2

50.7

7.3

68.8

183.5

14.0/13.4

76.7

56.8

62.9

49.1

8.7

52.3

226.5

13.7/10.7

89.7

74.4

89.1

84.4

127.1

4.3

68.1

158.6

8.5/8.4

9

86.8

66.4

118.6

85.6

53.5

7.1

65.4

146.3

14.1/14.0

10

338.9

79.5

65.9

70.3

70.3

5.8

57.8

212.5

10.0/.87

10

90.1

62.4

67.7

81.4

57.9

6.4

70.0

179.3

12.4/12.0

8

81.9

63.6

43.4

80.4

48.9

8.0

76.2

194.9

15.4/14.8

6

155.8

76.7

111.4

77.3

69.4

8.1

51.1

160.9

15.1/14.1

10

60.4

65.9

98.1

84.3

30.4

8.9

66.6

156.7

17.5/17.3

5

57.3

30.3

66.5

80.1

428.4

3.7

69.3

186.2

7.1/6.8

10

58.9

58.9

129.6

85.3

278.3

2.9

64.0

144.1

5.7/5.7

10

67.3

50.9

163.6

85.3

171.3

3.7

61.9

133.1

7.3/7.3

10

213.3

85.7

132.3

82.6

111.2

4.6

55.9

142.5

9.0/8.8

10

189.3

85.5

144.2

83.0

127.1

4.3

55.3

137.3

8.4/8.2

Lat

Early Cretaceous Kazarma River mouth, K1apt S4, Ogoneryuryakh (120) Fm. Kazarma River mouth, K1apt S3, Nadbulun Fm. (125) Cape Obukh, K1brm S22, Nadbulun Fm. (128) Cape Chucha, K1hau-brm S20, Chonkogor Fm. (130) Cape Chucha, K1hau S20, Chonkogor Fm. (132) Cape Chucha, K1hau S20, Chonkogor Fm. (135) Cape Chucha, K1vlg S18, Kigilyakh Fm. (136) Cape Chucha, K1vlg S17, Kigilyakh Fm. (138) Zhigansk Settlement, K1ber-vlg S24, Ygnyr Fm. (140) Cape Chekurov, K1ber-vlg S15, Khairgas Fm. (140) Cape Chekurov, K1ber S14, Khairgas Fm. (142)

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Middle Jurassic Cape Chekurov, S10, Chekurov Fm. Cape Chekurov, S8, Chekurov Fm. Cape Kystatym, S1, Kystatym Fm. Cape Kystatym, S2, Kystatym Fm.

J2bt (165) J2bt (165) J2bt (166) J2bj-bt (168)

Comment: Age – rock age (in brackets: absolute age in Ma accepted for the pole according stratigraphycal position of rock unit), : n - number of individual samples used in statistics; D paleomagnetic declination; I – paleomagnetic inclination, k – precision parameter (Fisher statistics); а95 – radius of 95% confidence limit.; Lat – VGP latitude (N degrees): Long – VGP longitude (E degrees.), dp/dm – semiaxes of VGP confidence oval.

The distribution of virtual geomagnetic poles (Table 10) is shown in Figure 30. A gradual northeastern shift of pole positions from Batian to Aptian is easily observed. The Jurassic and Cretaceous paleomagnetic poles from Siberian frame reported earlier, within the confidence limits coincide with those obtained for the inner part of the platform (Fig. 30). It is very important as in proposed models we postulate the absence of any significant movements between Siberian craton and it’s nearest southwestern folded frame at least since Late Jurassic. This assumption give grounds to use the paleomagnetic poles from Transbaikalia and Minusa together with Verkhoynsk poles for calculation of Siberian APW (Table 11). The

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Mesozoic APW path calculated for Siberia is shown in Figure 30. It is obvious that Siberian APW path in general follows the European one. The common features for both curves are the westward drift of poles during Jurassic with the subsequent sharp turn and the northern drift during Cretaceous. The similarity in the polar pathes reflects the common tectonic history of both Eurasian domains during Mesozoic. However, there are the principle differences in APW pathes. In particular pre-Late Cretaceous poles from Siberia are shifted relative to European ones and occupied more southern position. The angle between the corresponding poles decreases gradually from Jurassic to the end of Cretaceous. Such systematic deviation of Siberian poles from the European referent APWP suggests the presence of large-scale intraplate strike-slip motions of a whole assemblage of Siberian structures relative to European ones resulted form the clockwise rotation of Siberian domain within the “Stable Eurasia”.

Figure 29. Geological sketh map of the eastern margin of Siberian platform (a), after [Metelkin et al., 2008]. Legend: (1–9) Geological complexes: (1) -Cenozoic, (2) Upper Cretaceous, (3) Lower Cretaceous, (4) Jurassic, (5) Triassic, (6) Permian, (7) Devonian–Carboniferous, (8) Cambrian, (9) Precambrian; (10) sampling sites: (1) Zhigansk Settlement, (2) Cape Kystatym, (3) Cape Obukh, (4) Kazarma River mouth, (5) Kyusyur Settlement, (6) Cape Chucha, (7) Cape Chekurov. Typical orthogonal diagrams and NRM(T) plots based on results of stepwise thermal demagnetization of Lower Cretaceous (above panel) and Middle Jurassic (below panel) sandstone from the Verkhoyansk trough (b), after [Metelkin et al., 2008]..

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Table 11. The key paleomagnetic poles from Siberia used for APWP construction (see Fig. 30) Study object Late Cretaceous Diatreme of Minusa trough Early Cretaceous basalt of Transbaikalia (Khilok Fm.) Early Cretaceous sediments of Verkhoyansk Trough Late Jurassic basalt of Transbaikalia (Ichetuy Fm.) Late Jurassic basalt of Transbaikalia (Badin Fm.) Middle Jurassic sediments of Verkhoyansk Trough

Age, Ma 74-82 110130

n/N

Test

243/1 6 193/2 5

Rb, C+

Paleopole

References

Lat 82.8

Long 188.5

A95 6.1

T 75

Metelkin et al., 2007a

72.3

186.4

6.0

120

Metelkin et al., 2004b

67.2

183.8

7.8

135

Metelkin et al., 2008

140120

93/11

Rb, F+, G*+ F+

150160

156/1 8

Rc, F+, G*+

63.6

166.8

8.5

155

Metelkin et al., 2007b

150160 170160

86/12

Ro, F+

64.4

161.0

7.0

155

40/4

F+

59.3

139.2

5.7

165

Kravchinsky et al., 2002a Metelkin et al., 2008

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Comment: n/N - number of samples/number of sites used in pole calculation; Test -paleomagnetic tests: R - reversal test, where “b” and “c” indexes correspond to [McFadden, McElhinny, 1990] classification, “о” - means test inconclusive, F+ - positive fold test, С+ - positive baked contact test, G*+ - positive conglomerate test (intraformational conglomerate); paleomagnetic poleT - age, accepted for the pole.

To estimate a scale of the motion, an Euler pole that provide the best fit of Siberian poles with corresponding poles from Europe was calculate. In doing this we follow the conditions proposed by [Zonenshain et al, 1990], who was probably first to estimate the scale of the possible rotations of Siberia in Mesozoic on the base of migration of Mesozoic intraplate magmatism within the southern and southwestern margin of Siberian Platform. They are: i) the Euler pole position must be inside the Siberian craton; ii) the rotation of the platform must be clockwise. The first approximation of Euler pole which satisfies the conditions above points 60°N, 115°E and shows a good agreement (less than 10°) with Euler poles reported earlier [Bazhenov, Mossakovsky, 1986, Zonenshain et al, 1990, Voronov, 1997] for Siberia in Mesozoic, and also with our Paleozoic Euler pole [Kazansky, 2002]. Most likely, the kinematics of Siberian plate was inheritung even from Early Paleozoic and has essentially held up to the end of the Mesozoic. The best fitting for Middle and Late Jurassic poles with reference APWP for Europe is achieved through 45º (for 165 Ma) and 28° (for 155 Ma) while for Cretaceous through 17º (for 135 Ma) and 12° (for 120 Ma) rotation around the pole, respectively. The complete fit of the Late Cretaceous paleomagetic pole (for 75 Ma) with the European referent APWP testifies that the active tectonic processes connected with the intraplate strike-slip motions should be terminated. An average velocity of rotation during Jurassic-Early Cretaceous most likely did not exceed 0.7° per Ma. This data allows a rough estimation of Late Mesozoic strike-slips as first thousands kilometers (up to 500 km). Tectonic implication of the process seems to be opening and further evolution of the West-Siberian sedimentary basin, stress deformation within Altai-Sayan region and development of a number of rift-related depressions in Transbaikalia.

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Figure 30. Mesozoic pole positions from Siberia and Europe, аfter [Metelkin et al., 2008] (a) distribution of virtual geomagnetic poles (black dots) from Jurassic–Cretaceous terrigenous complexes of the Verkhoyansk Trough (Table 10). The black line with large white dots demonstrates averaged positions of these poles: APWP is constructed using the running mean method (averaging window 20 Ma, middle poles, spacing 5 Ma). Large black dots designate paleomagnetic pole positions available from structures surrounding the southwestern Siberian Craton (Table 11) and pole from Siberian Craton for 200 Ma (arbitrarily accepted pole #4417 from T2–J1 sandstone of the Lena River area from the IAGA Global Paleomagnetic Database (http://www.ngu. no/dragon/palmag/paleomag.htm) (b) Positions of averaged key Mesozoic paleomagnetic poles from the Siberian region (Siberian APWP, see Table 11) compared with the reference APWP available for the European region [Besse, Courtillot, 2002]. Numerals near poles indicate their ages. Ovals correspond to the 95% confidence limits for the corresponding pole.

CONCLUSION The tectonic history of the Siberian continental plate during the Neoproterozoic, Paleozoic and Mesozoic in global case is connected with the amalgamation and break-up of

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two supercontinents. We have reviewed Siberia's geological and paleomagnetic evidence that define successive change in the paleogeographic positions of the Siberian plate and the main tectonic features on the time frames during this nearly one billion year period, and conclude that in Siberia the transformation of the one tectonic event into another is often determined by intensity and scale of strike-slip motions. The Neoproterozoic stage corresponds to the Rodinia break-up [Li et al., 2008]. Combined analysis of available geological and paleomagnetic data suggest that at the Meso/Neoproterozoic boundary, the Siberia craton was part of the Rodinia supercontinent and may have represented a giant promontory in the southeast of the supercontinent. A similar viewpoint was discussed in [Pisarevsky et al., 2008]. In present-day coordinates Siberia was an extension of Laurentia in such a manner that the western margin of Siberia was a continuation of the western margin of Laurentia. Our paleomagnetic data show that during the Neoproterozoic, disintegration of the continental masses of Siberia and Laurentia was gradually developing from east to west along the southern (in modern coordinates) margin of Siberia under the predominant influence of strike slips, which have initiated rotation of Siberia [Metelkin et al., 2007]. The whole disconnection of Siberia has happened more than 100 Ma later than the beginning of the development of the destruction zones, zones of riftogenesis with associated magmatic activity in the southern margin of Siberia as it was proposed by [Yarmoluk, Kovalenko, 2001]. Neoproterozoic transform-strike-slip kinematics of development and evolution of oceanic basins around Siberia during the break up of Rodinia has determined dynamics of subsequent accretionary-collision events. Siberia was a substantial and independent terrane collage from the Neoproterozoic at about 750 Ma until close to the Permian–Triassic boundary time at 250 Ma [Cocks, Torsvik, 2007]. During this time interval, the Siberian plate underwent a predominantly northern drift from the equatorial latitudes of the Southern hemisphere (~ 10°S) in Precambrian to high latitudes of the Northern hemisphere (~60°N) at the end of the Paleozoic [Smethrust et al., 1998, Cocks, Torsvik, 2007]. According to the paleomagnetic data, Siberia during that time was gradually rotating predominantly clockwise at more than 180°, so that by the Triassic, the Siberian eastern margin faced north [Cocks, Torsvik, 2007]. The late Neoproterozoic stage is connected with the transformation of the passive continental margin in the west, north [Vernikovsky et al., 2003] and probably south [Khain et al., 2003] of Siberia into the active continental margin with development of the Late Neoproterozoic island arc systems. The stage of accretion of the Neoproterozoic island arc to the Siberian paleocontinent has been going on in the pre-Vendian [Vernikovsky et al., 2004]; however, even at the end of the Vendian the regime of active continental margin was again resumed at least in the southwestern Siberian plate [Sengor et.al., 1993, Mossakovsky et.al., 1993, Dobretsov et al., 2003]. Much of the Early Paleozoic island arc terranes make up the mosaic framework of the Central Asia fold belt on the western margins of the Siberian craton [Berzin et al., 1994]. But based on the available geologic and paleomagnetic evidence, we conclude that these island arc terranes are composed of fragments of a primary single and stretched island arc system which situated along the western and south-western (in modern coordinates) margins of Siberia. Reorganization and transformation of the arc system at the stage of accretion to the Siberian continent is connected with large-scale strike-slips and rotation of the Siberian plate. The rotation has resulted in “slipping and lagging” of periphery structures with subsequent complex displacement. Finally, the mosaic accretionary structure of the western and

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southwestern margin of the Siberian plate was completely organized even at the CambrianOrdovician boundary [Berzin, Dobretsov, 1994, Kungurtsev et al., 2001]. We conclude that strike-slip tectonics and deformation of new-generated crust in the west of Siberia were continuing up to the end of the Paleozoic [Fillipova et al., 2001, Van der Voo et al., 2006]. Large-scale transform-strike-slip movements during the Paleozoic are known not only in the west but also in the north of Siberia. According to paleomagnetic data from Paleozoic sediments of the Kara plate [Metelkin et al., 2005], the microcontinent was located between Baltica and Siberia and drifted northwards from moderate latitudes (about 40°S) in the southern hemisphere to subequatorial latitudes (about 10°N) in the northern hemisphere with a simultaneous counter-clockwise rotation of more than 65°. These motions of the Kara are interpreted as to have been related to large-scale transform strike–slip fault zones [Metelkin et al., 2005]. We conclude that the approach and subsequent collision of the Kara microcontinent with Siberia in the Late Carboniferous to Permian time occurred as a result of strike–slip tectonics. Deformation of the Paleozoic margins of Siberia and Kara resulted from differential rotations of these continental blocks. By the end of the Paleozoic the closure of the Precambrian - Early Paleozoic oceans and collision of Siberia Baltica, Kazakh Terrane Assemblage and Kara resulted in composition of the main structure of the modern Eurasian plate. Siberia along with the other continental masses was included into the composite structure of the Eurasian plate and formed the Laurasian part of the Pangea supercontinent. This key moment in the tectonic history of Siberia has been manifested by the dramatic trap eruption well known as the Siberian Large Igneous Province. Our paleomagnetic correlations testify that the Siberian Large Igneous Province occurred extremely fast. The duration of the intensive magmatic phase in different regions of LIP varies from 1 to 5 Ma and was controlled in the south (Kuznetsk trough) and probably in the west (West Siberia) by large-scale strike-slip faults. Much of the old terrane into Siberia, as well as Permian-Triassic traps on the Siberian frames, is now masked by substantial, almost not deformed Mesozoic and Cenozoic sediments, the West Siberia province for example. And many authors considered the Mesozoic to Cenozoic interval to be for Siberia a time of completely stable domain of the Eurasian continent. Available paleomagnetic data for the Siberian tectonic domain show significant diversities both in paleolatitudes and paleomeridians for Siberia compared with those from Europe and China. On the base of combined geological evidence [Voronov, 1997] and our paleomagnetic data, we can conclude that the Eurasian continent in the Mesozoic was not a rigid plate with an absloutely stable inner structure. We have shown that the Mesozoic reorganization of the structure of the Central Asian mobile belt, that “sewing” of the structures of Siberian and East-European ancient continental masses was directly connected with strike-slip motions. Similar ideas were proposed by [Bazhenov, Mossakovsky, 1986, Natal'in and Sengor, 2005, Van der Voo, 2006]. According to our tectonic model based on paleomagnetic evidence, deformation of the Central Asian crust during the Mesozoic resulted from interplate strike-slip motions that were governed by clockwise rotation of the Siberian domain relative to the other tectonic domains of the Eurasian plate (Fig. 31). Geologic implication of Mesozoic strike-slip tectonics appears to be: strain environment and rift-related intracontinental grabens on the basement of West Siberia Mesozoic sedimentary basin as well as dynamics of its development during the Mesozoic form the one side and stress environment resulting in crust deformation and Mesozoic orogeny in the south western

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(Central Asia tectonic province) margin of Siberian craton from the other hand. New paleomagnetic evidence from Transbaikalia in the framework of our tectonic model allows us to describe the kinematics of the Mongolo-Okhotsk ocean closure. [Zorin, 1999; Kravchinsky et al., 2002]. Progressive closure of the ocean from west to east [Kravchinsky et al., 2002] was controlled by significant sinistral strike-slip motion of Siberian domain. Geological implication of this process in Transbaikalia is represented by intensive bimodal volcanism that related with depressions with well developed rift-related structures like pull-apart.

Figure 31. Late Paleozoic - Early Mesozoic paleotectonic reconstruction of Eurasia showing sinistral transpression between the converging Siberia and Baltica resulted from clockwise rotations and intraplate shifts of Siberian tectonic domain. Adopted and modified from [Natal’in and Sengor, 2005] and [Van der Voo et al., 2006].

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Thus, our paleomagnetic results from Siberia show that strike-slip motions play a critical role in tectonics of Siberian plate at the main stages of its history. As a rule, kinematics of late preceding tectonic stage in many respects was determined by kinematics of the earlier one. It is of first importance that the pole of rotation of the Siberian plate (in plate coordinate system) remains nearly constant (about 50-60°N 110-120°E) during the whole Phanerozoic. Most likely, that main kinematics of Siberian plate that initiated even at the end of Precambrian-Early Paleozoic was preserved up to the end of Mesozoic and probably in Cenozoic. Cenozoic motions are rather small and are out of accuracy of the paleomagnetic method, however GPS data confirm our suggestions. It, in particular, comes from comparison of Paleozoic and Mesozoic rotation pole positions based on paleomagnetic data with virtual rotation pole position for rotation of Siberia relative to its southern folded frame (Amur plate) obtained from GPS [Timofeev et al., 2008] data. The poles do not differ in confidence limits of paleomagnetic method. The nearly constant position of the pole of rotation of the Siberian craton relative to its marginal structures (in the Siberian plate coordinate system) testifies to the perpetual rotation of the Siberian domain within the structure of the Eurasian plate. The clockwise rotation of the Siberian tectonic domain during the Paleozoic and Mesozoic actually represents a global process, which connected with over-Earth plate motion. Moreover, one can see the gradual retardation of the rotation — since the end of the Cretaceous, the motion becomes less than the accuracy of the paleomagnetic method and the virtual velocity (by GPS data) is 10 times smaller than those in the Early Mesozoic. The proposed scale of the Neoproterozoic movements is estimated at more than one thousand kilometers. Despite the scale, Mesozoic displacements are much smaller (first hundred kilometers), they play a critical role in the development of the present-day structure of South and West Siberia.

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ACKNOWLEDGMENTS We thank Rob Coe and Xixi Zhao, University of California Santa Cruz, and Trond Torsvik for the facilities and use of equipment in the paleomagnetic laboratories of Santa Cruz and Lund. This work is supported by integration grants 7.10.1, 7.10.2. and by the Siberian Branch of the Russian Academy of Sciences and by grant 07-05-01026 from the Russian Foundation of basic research.

REFERENCES Al’mukhamedov, A.I., Medvedev, A.Yu., Kirda, N.P., 1999. Comparative analysis of geodynamic settings of the Permo-Triassic magmatism in East Siberia and West Siberia. Russ. Geol. Geophys. 40(11), 1550–1561. Baksi, A.K., Farrar, E., 1991. 40Ar/39Ar dating of whole rock basalts (Siberian Trapps) in the Tungusska and Noril’sk areas, USSR. EOS 72, p.570.

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Bazhenov, M.L., Mossakovsky, A.A., 1986. Horizontal movements of the Siberian Platform in the Triassic: paleomagnetic and geological evidence. Geotektonika 1, 59–69 (in Russian). Belichenko, V.G., Sklyarov, E.V., Dobretsov, N.L., Tomurtogoo, O. 1994. Geodynamic map of the Palaeoasian ocean: eastern segment. Russ. Geol. Geophys. 35 (7–8), 29-40. Berzin, N.A. and L.V. Kungurtsev, 1996 Geodynamic interpretation of Altai-Sayan geological complexes. Russ. Geol. Geophys. 37(1), 63–81. Berzin, N.A. and N.L. Dobretsov, 1994. Geodynamic evolution of Southern Siberia in late Precambrian-early Paleozoic time. In: Coleman, R.G. (Ed.), Reconstruction of the PaleoAsian Ocean, VSP Intern. Sci. Publ., The Netherlands, 45-62 Berzin, N.A., Coleman, R.G., Dobretsov, N.L., Zonenshain, L.P., Xiao, X.C., Chang, E.Z., 1994. Geodynamic map of the western Palaeoasian ocean. Russ. Geol. Geophys.35 (7–8), 8–28. Besse, J., Courtillot, V., 1991. Revised and synthetic apparent polar wander paths of African, Eurasian, North-American and Indian true polar wander since 200 Ma. J. Geophys. Res. 96, 4029–4050. Besse, J., Courtillot, V., 2002. Apparent and true polar wander and geometry of the geomagnetic field over the last 200 Myr. J. Geophys. Res. 107 (B11), 1–31. Bogdanov, N.A., Khain V.E., Rosen, O.M., Shipilov, E.V., Vernikovsky, V.A., Drachev, S.S., Kostyuchenko S.H., 1998. Tectonic Map of the Kara and Laptev Seas and North Siberia (scale 1:2,500,000). Explanatory notes. Moscow, Inst. Lithosphere of Marginal Seas, 116 pp. Bogolepova, O.K., Gubanov, A.P., Raevskaya, E.G., 2001. The Cambrian of the Severnaya Zemlya archipelago, Russia. Newsletter Stratigraphy, 39, 73– 91. Bragin, V.Y., Reutsky, V.N., Litasov, K.D., Malkovets, V.G., Travin, A.V., Mitrokhin, D.V., 1999a. Paleomagnetism and 40Ar/39Ardating of Late Mesozoic volcanic pipes of Minusinsk depression (Russia). Physics and Chemistry of the Earth 24 (6), 545–549. Buslov, M.M., Saphonova, I.Yu., Watanabe, T., Obut, O.T., Fujiwara, Y., Iwata, K., Semakov, N. N., Sugai, Y., Smirnova, L.V., Kazansky, A.Yu. and Itaya, T. 2001. Evolution of the Paleo-Asian Ocean (Altai-Sayan Region, Central Asia) and collision of possible Gondwana-derived terranes with the southern marginal part of the Siberian continent. J. Geosci. 5, 203-224 Campbell I.H., Czamanske G.K., Fedorenko V.A., Hill R.I., Stepanov V. 1992. Synchronism of the Siberian Trapps and the Permian-Triassic boundary. Science 258, 1760-1763 Claoue-Long, J.C., Zichao, Z., Gougan, V., Shaohua, D. 1991. The age of the PermianTriassic boundary. Earth Planet. Sci. Lett. 105, 182 - 190. Cocks L.R.M., Torsvik T.H. 2005. Baltica from the late Precambrian to mid-Palaeozoic times: the gain and loss of a terrane’s identity. Earth-Science Reviews 72, 39–66 Cocks, L.R.M., Torsvik, T.H., 2007. Siberia, the wandering northern terrane, and its changing geography through the Palaeozoic. Earth-Science Reviews 82, 29–74 Condie, K.C., Rosen, O.M. 1994. Laurentia–Siberia connection revisited. Geology 22, 1994, 168–170. Dalrymple, G.B., Czamanske, G.K., Lanphere, M.A., Stepanov, V. and Federenko V., 1991. 40 Ar/39Ar ages from samples from Noril’sk -Talnakh ore bearing intrusions and the Siberian flood basalts, Siberia. EOS 72, 570.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Copyright © 2009. Nova Science Publishers, Incorporated. All rights reserved.

226

D.V. Metelkin, A.Yu. Kazansky and V.A. Vernikovsky

Dalziel, I.W.D., 1991. Pacific margins of Laurentia and East Antarctica–Australia as a conjugate rift pair: evidence and implications for an Eocambrian supercontinent. Geology 19, 598–601. Didenko, A., Pechersky, D., 1993. Revised paleozoic apparent polar wander paths for E. Europe, Siberia, N. China and Tarim Plates. Abstracts of L.P. Zonenshain Memorial Conference on Plate Tectonics, Moscow, p.47. Didenko, A.N., Mossakovsky, A.A., Pechersky, D.M., Ruzhentsev, S.V., Samygin, S.G., Kheraskova, T.N., 1994. Geodynamics of the Central-Asian Palaeozoic oceans. Russ. Geol. Geophys. 35 (7-8), 59–75. Diehl, J.F., Haig, T.D., 1994. A paleomagnetic study of the lava flows within the Copper Harbor conglomerate, Michigan: new results and implications. Can. J. Earth Sci. 31, 369–380. Dobretsov, N.L., 1997. Permian–Triassic magmatism and sedimentation in Eurasia as a result of a superplume. Dokl. Earth Sci. 354 (4), 497. Dobretsov, N.L., 2005. 250 Ma large igneous provinces of Asia: Siberian and Emeishan traps (plateau basalts)and associated granitoids. Russ. Geol. Geophys. 46(9), 847-868 Dobretsov, N.L., Buslov, M.M., Vernikovsky, V.A., 2003. Neoproterozoic to Early Ordovician evolution of the Paleo-Asian Ocean: implications to the break-up of Rodinia. Gondwana Res. 6 (2), 143– 159. Dobretsov, N.L., Vernikovsky, V.A., 2001. Mantle plumes and their geological manifestations. Int. Geol. Rev. 43, 771– 787. Enkin, R.J., 2003. The direction-correction tilt test: an all-purpose tilt/fold test for paleomagnetic studies. Earth Planet. Sci. Lett. 212, 151–166. Ernst, R.E., Buchan, K.L., 1993. Paleomagnetism of the Abitibi dyke swarm, southern Superior Province, and its implications for the Logan Loop. Can. J. Earth Sci. 30, 1886– 1897. Filippova, I.B., Bush, V.A., Didienko, A.N., 2001. Middle Paleozoic subduction belts: The leading factor in the formation of the Central Asian fold-and-thrust belt. Russ. J. Earth Sci. 3(6), 405–426. Frost, B.R., Avchenko, O.V., Chamberlain, K.R., Frost, C.D., 1998. Evidence for extensive Proterozoic remobilization of the Aldan Shield and implications for Proterozoic plate tectonic reconstructions of Siberia and Laurentia. Precamb. Res. 89, 1–23. Gallet, Y., Pavlov, V.E., Semikhatov, M.A., Petrov, P.Yu., 2000. Late Mesoproterozoic magnetostratigraphic results from Siberia: paleogeographic implications and magnetic field behaviour. J. Geophys. Res. 105, 16481–16499. Gilder S., Courtillot V., 1997 Timing of North-South China collision from new middle to Late Mesozoic paleomagnetic data from the North China Block, J. Geophys. Res. 102, 17,713– 17,727. Gladkochub, D.P., Wingate, M.T.D., Pisarevsky, S.A., Donskaya, T.V., Mazukabzov, A.M., Ponomarchuk, V.A., Stanevich, A.M., 2006. Mafic intrusions in southwestern Siberia and implications for a Neoproterozoic connection with Laurentia. Precamb. Res. 147, 260– 278. Golovin, A.V., Sharygin, V.V., Mal’kovets, V.G., 2000. Evolution of melt during crystallization of the Bele pipe basanites (North Minusa depression). Russ. Geol. Geophys. 41(12), 1710–1731.

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Paleomagnetic Evidence for Siberian Plate Tectonics

227

Gordienko, I.V., 2006. Geodynamic evolution of late Baikalides and Paleozoids in the folded periphery of the Siberian craton. Russ. Geol. Geophys.47(1), 51-67. Gordienko, I.V., Bayanov, V.D., Klimuk, V.S., Ponomarchuk, V.A., Travin, A.V., 1999 The composition and 40Ar/39Ar age of volcanogenic rocks of the Chikoi-Khilok rift valley in Transbaikalia. Russ. Geol. Geophys. 40(4), 566–575. Gordienko, I.V., Klimuk, V.S, 1995. Bimodal volcanism of the Tugnui Rift Depression (Transbaikalia). Russ. Geol. Geophys. 36(5), 22–36. Gordienko, I.V., Klimuk, V.S., Ivanov, V.G., Posokhov, V.F., 1997. New Data on Composition and Age of Bimodal Volcanic Series of the Tugnui Riftogenic Depression, Trans-Baikal Region. Dokl. Earth Sci. 353(2), 273-277 Gordienko, I.V., Klimuk, V.S., Quan Heng, 2000. The Upper Amur volcanoplutonic belt in Eastern Asia: structure, composition, and geodynamic setting. Russ. Geol. Geophys. 41(12), 1602–1618. Gordienko, I.V., Kuz’min, M.I., 1999. Geodynamics and metallogeny of the MongoloTransbaikalian region. Russ. Geol. Geophys. 40 (11), 1522–1538. Gordienko, I.V., Zhamoitsina, L.G., 1995. The margintui zeolite deposit. In: Transbaikalian Deposits. Chita, vol. 1, book 2, 234–239. (in Russian) Green, J.C., Bornhorst, T.J., Chandler, V.W., Mudrey, M.D., Myers, P.E., Pesonen, L.J., Wilband, J.T., 1987. Keewanawan dykes of the Lake Superior region: evidence for evolution of the middle Proterozoic mid-continent rift in North America, in: Halls, H.C., Fahrig, W.F. (Eds.), Mafic Dyke Swarms. Geol. Assoc. Can. Spec., 289–302. Gurevitch, E.L., Heunemann, C., Radko, V., Bachtadse, V., Pozzi, J.P., Feinberg, H., Westpfal, M., 2004. Paleomagnetism and magnetostratigraphy of the Permo-Triassic Siberian traps. Tectonophysics 379, 211–226. Gurevitch, E.L., Westphal, M., Daragan-Suchov, J., Feinberg, H., Pozzi, J.P., Khramov, A.N., 1995. Paleomagnetism and magnetostratigraphy of the traps fromWestern Taimyr (northern Siberia) and the Permo-Triassic crisis. Earth Planet. Sci. Lett. 136, 461–473. Halls, H.C., 1974. A paleomagnetic reversal in the Osler Volcanic Group, northern Lake Superior. Can. J. Earth Sci. 11, 1200–1207. Halls, H.C., 1976. A least squares method to find a remanence direction from converging remagnetization circles. Geophys. J. R. Astron. Soc. 5, 297– 304. Halls, H.C., Palmer, H.C., 1981. Remagnetization in Keewanawan rocks: Part II. Lava flows within the Copper Harbor Conglomerate. Can. J. Earth Sci. 18, 1395–1408. Halls, H.C., Pesonen, L.J., 1982. Paleomagnetism of Keewanawan rocks, in: Wold, R.J., Hinze, W.J. (Eds.), Geology and Tectonics of the Lake Superior Basin. Geol. Soc. Amer. Mem., vol. 156, pp. 173–201. Hankard, F., Cogne, J.P., Kravchinsky, V., 2005. A new Late Cretaceous paleomagnetic pole for the west of Amuria block (Khurmen Uul, Mongolia). Earth Planet. Sci. Lett. 236, 359– 373. Harlan, S.S., Geissman, J.W., Snee, L.W., 1997. Paleomagnetic and 40Ar/39Ar geochronologic data from late Proterozoic mafic dykes and sills, Montana and Wyoming, USGS Prof. Pap., 16–25. Heaman, L.M., LeCheminant, A.N., Rainbird, R.H., 1992. Nature and timing of Franklin igneous event, Canada: implications for a Late Proterozoic mantle plume and the breakup of Laurentia. Earth Planet. Sci. Lett. 109, 117–131.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Copyright © 2009. Nova Science Publishers, Incorporated. All rights reserved.

228

D.V. Metelkin, A.Yu. Kazansky and V.A. Vernikovsky

Hoffman, P.F., 1991. Did the breakout of Laurentia turn Gondwanaland insideout? Science 252, 1409–1412. Hyodo, H., Dunlop, D.J., 1993. Effect of anisotropy on the paleomagnetic contact test for a Grenville dyke. J. Geophys. Res. 98, 7997–8017. Hyodo, H., Dunlop, D.J., McWilliams, M.O., 1986. Timing and extent of Grenvillian overprinting near Temagami. Geol. Soc. Can. Spec. Pap. 31, 119–126. Inger, S., Scoot, R.A., Golionko, B.G., 1999. Tectonic evolution of the Taimyr Peninsula, northern Russia: implications for Arctic continental assembly. J. Geol. Soc., London, 156, 1069– 1072. Irving, E., Park, J.K., Roy, J.L., 1972. Paleomagnetism and the origin of the Grenville Front. Nature 236, 344–346. Ivanov, V.G., Yarmoluyk, V.V., Smirnov, V.N., 1995 New data on the age of volcanism manifestation in the Late Mesozoic-Cenozoic West Transbaikalia volcanic region. Dokl. Earth Sci. 345(5), 648-652 Kamo, S.L.,Czamanske, G.K.,Amelin,Y., Fedorenko,V.A., Davis, D.W., Trofimov,V.R., 2003. Rapid eruption of Siberian flood-volcanic rocks and evidence for coincidencewith the Permian–Triassic boundary and mass extinction at 251 Ma. Earth Planet. Sci. Lett. 214, 75–91. Kazansky, A.Yu., 2002. Evolution of structures of western margin of Siberian Platform after paleomagnetic data. Abstract of ScD thesis, UIGGM SB RAS, Novosibirsk, (in russian), 40 pp. Kazansky, A.Yu., Buslov, M.M. and D.V. Metelkin, 1998. Evolution of the Paleozoic accretion-collision structure of Gorny Altai: correlation of paleomagnetic and geological data. Russ. Geol. Geophys. 39(3), 297-306. Kazansky, A.Yu., Kazansky, Yu.P., Saraev S.V., Moskvin V.I. 2000 The Permo-Triassic boundary in volcano-sedimentary section of the West Siberian plate according to paleomagnetic data (from studies of the Tymenskaya superdeep borehole SDB-6). Russ. Geol. Geophys. 41(3), 323-335 Kazansky, A.Yu., Kungurtsev, L.V., Bragin, V.Yu., 1996. Paleomagnetic directions of Devonian complexes of eastern Altai-Sayan Folded Area. In: Paleomagnetism and magnetism of rocks. Moscow, 48–50 (in Russian) Kazansky, A.Yu., Metelkin, D.V., Bragin, V.Yu., Kungurtsev, L.V., 2005. Paleomagnetism of the Permian-Triassic traps from the Kuznetsk Basin, southern Siberia. Russ. Geol. Geophys. 46(11), 1089–1102. Kazansky, A.Yu., Metelkin, D.V., Kungurtsev, L.V. and A.V. Lavrenchuk 1999. New paleomagnetic data on the Early Cambrian of West Sayan. Russ. Geol. Geophys. 40(4), 526-545 Kazansky, A.Yu., Metelkin, D.V., Kungurtsev, L.V. and P.A. Kizub, 2003a. Kinematics of the Martaiga block of the Kuznetsk-Alatau paleoisland arc during the Late Vendian Early Ordovician as inferred from paleomagnetic data. Russ. Geol. Geophys. 44(3), 181197. Kazansky, A.Yu., Stupakov, S.I., Simonov, V.A. and D.V. Metelkin, 2003b. Geodynamics of ophiolites of the Srednyaya Ters’ massif (Kuznetsk Alatau) inferred from paleomagnetic data. Russ. Geol. Geophys. 44(10), 1000-1010. Khain, E.V., Bibikova, E.V., Salnikova, F.B., Kröner, A., Gibsher, A.S., Didenko, A.N., Degtyarev, K.E., Fedotova, A.A., 2003. The Palaeo-Asian ocean in the Neoproterozoic

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Paleomagnetic Evidence for Siberian Plate Tectonics

229

and early Palaeozoic: new geochronologic data and palaeotectonic reconstructions. Precambrian Research 122, 329–358. Kheraskova T. N. and E. V. Gavrilova, 1996. Upper Riphean Cambrian Carbonates of the Batenevskii Range (Kuznetsk Ala Tau): Implications for Past Tectonic and Sedimentation Environment. Geotectonics 30(3), 217-228 Khomentovsky, V.V., 2002. Baikalian of Siberia (850–650 Ma). Russ. Geol. Geophys. 43(4), 299–318. Khramov, A.N., Rodionov, V.P., 1980. Palaeomagnetism and reconstruction of palaeogeographic position of the Siberian and Russian plates during the Late Proterozoic and Paleozoic. J. Geomagn.Geoelectr. 32(3), 23-37. Khramov, A.N., Ustritsky, V.I., 1990. Paleopositions of some northern Eurasian tectonic blocks: paleomagnetic and paleobiologic constraints. Tectonophysics, 184, 101– 109. Kirschvink, J.L., Ripperdan, R.L., Evans, D.A., 1997. Evidence for a large-scale reorganization of Early Cambrian continental masses by inertial interchange True Polar Wander. Science 277, 541–545. Kirschvink, J.L., Rozanov, A.Yu., 1984. Magnetostratigraphy of lower Cambrian strata from the Siberian Platform: a palaeomagnetic pole and a preliminary polarity time-scale. Geol. Mag. 121, 189–203 Kravchinsky, V.A., Cogne, J.-P., Harbert, W.P., and M.I. Kuzmin, 2002a. Evolution of the Mongolo-Okhotsk Ocean as constrained by new palaeomagnetic data from the Mongol.Okhotsk suture zone, Siberia. Geophys. J. Int. 148, 34-57. Kravchinsky, V.A., Konstantinov, K.M., Cogne, J.P., 2001. Paleomagnetic study of Vendian and early Cambrian rocks of South Siberia and Central Mongolia: was the Siberian platform assembled at this time? Precamb. Res. 110, 61–92. Kravchinsky, V.A., Konstantinov, K.M., Courtillot, V., Savrasov, J.I., Valet, J.-P., Cherniy, S.D., Mishenin, S.G., Parasotka, B.S., 2002b Palaeomagnetism of East Siberian traps and kimberlites: two new poles and palaeogeographic reconstructions at about 360 and 250 Ma. Geophys. J. Int. 148, 1–33. Kravchinsky, V.A., Sorokin, A.A., Courtillot, V. 2002c. Paleomagnetism of Paleozoic and Mesozoic sediments from the southern margin of Mongolo-Okhotsk ocean, far eastern Russia. J. Geophys. Res. 107 (B10), 1–22 Kungurtsev, L.V., Berzin, N.A., Kazansky, A.Yu. and D.V. Metelkin, 2001. Tectonic evolution of the southwestern framing of the Siberian platform in the Vendian-Cambrian according to paleomagnetic data. Russ. Geol. Geophys. 42(7), 1042-1051 Kutolin, V.A. Trap formation of the Kuznetsk basin. Izd. AN SSSR, Novosibirsk, 117 pp. (in russian) Lavrenchuk, A.V., Metelkin, D.V., Belonosov, I.V., 2005. New petrologogeochemical and paleomagnetic data on Neoproterozoic dike complexes of Sayan-Yenisei margin of Siberian craton. Vestnik Tomskogo Universiteta. Application: Proc. of Sci. Conf. “Petrology of magmatic and metamorphic complexes”, Tomsk, 100–105. (in Russian) Lewchuk, M.T., Symons, D.T.A., 1990. Paleomagnetism of the late Precambrian Coldwell Complex, Ontario, Canada. Tectonophysics 184, 73–86. Li, Z.X., Bogdanova, S.V., Collins, A.S., Davidson, A., Waele, B. De, Ernst, R.E., Fitzsimons, I.C.W., Fuck, R.A., Gladkochub, D.P., Jacobs, J., Karlstrom, K.E., Lul, S., Natapov, L.M., Pease, V., Pisarevsky, S.A., Thrane, K., Vernikovsky, V., 2008.

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230

D.V. Metelkin, A.Yu. Kazansky and V.A. Vernikovsky

Assembly, configuration, and break-up history of Rodinia: A synthesis. Precamb. Res. 160, 179–210 Li, Z.X., Zhang, L., Powell, C.M., 1995. South China in Rodinia: part of the missing link between Australia-East Antarctica and Laurentia? Geology 23, 407–410. Lind, E.N., Kropotov, S.V., Czamanske, G.K., Gromme, S.C. and Fedorenko, V.A., 1994. Paleomagnetism of the Siberian flood basalts of the Noril’sk area: a constraint on eruption duration. Int. Geol. Rev., 36, 1139–1150. Litvinovsky, B.A., Zanvilevich, A.N., Shadaev, M.G., Lyapunov, S.M., 1996. Contribution of fraction crystallization into the formation of a bimodal trachybasalt-trachyte series: Maly Khamar-Daban volcanotectonic structure, Transbaikalia. Petrologiya 4(1), 26–45. Mal’kovets, V.G., 2001. Composition and structure of Mesozoic upper mantle below North Minusa Depression (according to data of study of mantle xenoliths from alkali-basaltoids explosion pipes). Abstract of PhD Thesis. UIGGM SB RAS, Novosibirsk, 24 pp. (in Russian) Mardia, K.V., 1972. Statistics of Directional Data. Academic Press, London. 357 pp. McCabe, C., Van der Voo, R., 1983. Paleomagnetic results from the upper Keweenawan Chequamegon Sandstone: implications for red bed diagenesis and Late Precambrian apparent polar wander of North America. Can. J. Earth Sci. 20, 105–112. McElhinny, M.W., 1964. Statistical significance of the fold test in paleomagnetism. Geophys. J. R. astr. Soc. 8, 338–340. McElhinny, M.W. and Lock, J., 1996. IAGA paleomagnetic databases with access, Surv. Geophys., 17, 575–591. McElhinny, M.W., McFadden, P.L., 2000. Paleomagnetism Continents and Oceans. Academic Press, San Diego. 386 pp. McFadden, P.L., 1990. A new fold test for paleomagnetic studies. Geophys. J. Int. 103, 163 – 169. McFadden, P.L., McElhinny, M. W., 1990. Classification of reversal test in paleomagnetism. Geophys.J.Int. 103, 725-729. McFadden, P.L., McElhinny, M.W., 1988. The combined analysis of remagnetization and direct observation in paleomagnetism. Earth Planet. Sci. Lett., 87, 161– 172. McWilliams, M.O., Dunlop, D.J., 1978. Grenville paleomagnetism and tectonics. Can. J. Earth Sci. 15, 687–695. Meert, J.G., Torsvik, T.H., 2003. The making and unmaking of a supercontinent: Rodinia revisited. Tectonophysics 375, 261–288. Merkulov, V.P., 1982 Paleomagnetic investigation of Upper Proterozoic and Cambrian deposits from eastern slope of Kuznetsk Alatau. Abstract of PhD thesis, Tomsk, 20 p. (in russian) Metelkin D.V., Vernikovsky V.A., Kazansky A.Yu., Bogolepova O.K., Gubanov A.P., 2005b. Paleozoic history of the Kara microcontinent and its relation to Siberia and Baltica: paleomagnetism, paleogeography and tectonics. Tectonophysics 398, 225-243 Metelkin, D. V., Gordienko, I. V., Zhao X., and V.S. Klimuk, 2003 Early Cretaceous Geodynamics of the Transbaikal Region: Paleomagnetic Aspect. Dokl. Earth Sci. 393A (9), 1221-1226 Metelkin, D.V., Belonosov, I.V., Gladkochub, D.P., Donskaya, T.V., Mazukabzov, A.M., Stanevich, A.M., 2005c. Paleomagnetic directions from Nersa intrusions of the Biryusa

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Paleomagnetic Evidence for Siberian Plate Tectonics

231

terrane, Siberian Craton, as a reflection of tectonic events in the Neoproterozoic. Russ. Geol. Geophys. 46(4), 395–410. Metelkin, D.V., Gordienko, I.V. and Xixi Zhao, 2004b. Paleomagnetism of Early Cretaceous volcanic rocks from Transbaikalia: argument for Mesozoic strike-slip motions in Central Asian structure. Russ. Geol. Geophys. 45(12), 1349–1363. Metelkin, D.V., Gordienko, I.V., Klimuk, V.S. 2007b. Paleomagnetism of Upper Jurassic basalts from Transbaikalia: new data on the time of closure of the Mongolo-Okhotsk Ocean and Mesozoic intraplate tectonics of Central Asia. Russ. Geol. Geophys. 48(10), 825–834 Metelkin, D.V., Kazansky, A.Yu. and L.V. Kungurtsev, 2000. Kuznetsk Alatau structure in Middle - Late Cambrian from paleomagnetic data. Russ. Geol. Geophys. 41(6), 772-784. Metelkin, D.V., Kazansky, A.Yu., Bragin, V.Yu., Tsel’movich, V.A.,. Lavrenchuk, A.V., Kungurtsev, L.V., 2007c. Paleomagnetism of the Late Cretaceous intrusions from the Minusa trough (southern Siberia) Russ. Geol. Geophys. 48 (2), 185–198 Metelkin, D.V., Kazansky, A.Yu., Gordienko, I.V., Mikhal’tsov, N.E., 2006. Preliminary paleomagnetic data from volcano-sedimentary formations of Eravna terrane. In: Geodynamic evolution of Central Asia mobile belt Litosphere (from ocean to continent). Proceeding of scientific meeting Iss.4 v.2, Irkutsk, 16-19. (in russian) Metelkin, D.V., Kazansky, A.Yu., Kungurtsev, L.V., 1997. Paleomagnetism and Geodynamics of Cambrian Island Arc Complexes of West Sayan (Russia). In: Paleomagnetism of Collision Belt, v.1, Geoscience Laboratory Project, GSP, Islamabad, Pakistan, 101-112 Metelkin, D.V., Vernikovsky, V.A., 2003. Preliminary paleomagnetic data from the Neoproterozoic Central Taimyr Accretionary belt (Arctic Siberia) and Siberia-Laurentia connection. in: The Fourth International Conferenceon Arctic Margins (ICAM IV). Dartmouth, Nova Scotia, Canada, p. P-15. Metelkin, D.V., Vernikovsky, V.A., and A.Yu. Kazansky, 2007a. Neoproterozoic evolution of Rodinia: constraints from new paleomagnetic data on the western margin of the Siberian craton. Russ. Geol. Geophys. 48(1), 32-45 Metelkin, D.V., Vernikovsky, V.A., Belonosov, I.V., 2004a. Paleomagnetism of volcanogenic complexes from the Predivinsk terrane of the Yenisei Ridge: Geodynamic implications. Dokl. Earth Sci. 399(8), 1080–1084. Metelkin, D.V., Vernikovsky, V.A., Kazansky, A.Yu. and I. V. Belonosov, 2005a. The Siberian Craton in the Structure of the Supercontinent Rodinia: Analysis of Paleomagnetic Data. Dokl. Earth Sci. 404(7), 1021-1026 Metelkin, D.V., Vernikovsky, V.A., Kazansky, A.Yu., Kashirtsev, V.A., Bragin, V.Yu., Kungurtsev, L.V., 2008. The Mesozoic Apparent Polar Wander Path for the Siberian Domain of the Eurasian Plate. Dokl. Earth Sci. 418(1), 62–67 Molostovsky, E.A., Khramov, A.N., 1984. Paleomagnetic Phanerozoic scale and problems of magnetostratigraphy. In: Proceedings of the 27-th IGC. Stratigraphy, section C01. Reports, v.1, Nauka, Moscow, 16-23. (in russian) Mossakovsky, A.A., Ruzhentsev, S.V., Samygin, S.G., Kheraskova, T.N., 1993. Central Asian fold belt: geodynamic evolution and history of formation. Geotectonics 6, 3–33. Murthy, G., Gower, C., Turrett, M., Pa’tzold, R., 1992. Paleomagnetism of the Eocambrian Long Range dykes and Double Mer Formation from Labrador, Canada. Can. J. Earth Sci. 29, 1224–1234.

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D.V. Metelkin, A.Yu. Kazansky and V.A. Vernikovsky

Natal'in, B.A., Sengör, A.M.C., 2005. Late Palaeozoic to Triassic evolution of the Turan and Scythian platforms: the pre-history of the palaeo-Tethyan closure. Tectonophysics 404, 175–202 Opdyke, N.D., Channel, J.E.T., 1996. Magnetic stratigraphy. Academic Press., NY, 346 p. Palmer, H.C., Baragar, W.R.A., Fortier, M., Foster, J.H., 1983. Paleomagnetism of Late Proterozoic rocks, Victoria Island, North-west Territories, Canada. Can. J. Earth Sci. 20, 1456–1469. Palmer, H.C., Davis, D.W., 1987. Paleomagnetism and U-Pb geochronology of volcanic rocks from Michipicoten Island, Lake Superior, Canada: precise calibration of the Keweenawan polar wander track. Precamb. Res. 37 (2), 157–171. Parfenov L.M. Prokopiev A.V., Gaiduk V.V. 1995. Cretaceous frontal trusts of the Verkhoyansk fold belt, Eastern Siberia. Tectonics 4(2), 342-358 Parfenov, L.M. and M.I. Kuz’min (Eds.) 2001. Tectonics, Geodynamics, and Metallogeny of the Sakha Republic (Yakutia) Territory. Nauka/Interperiodika, Moscow, 571 pp. (in Russian). Parfenov, L.M., Bulgatov, A.N., Gordienko, I.V., 1995. Terranes and accretionary history of the Transbaikal Orogenic Belt. Int. Geol. Rev. 37, 736–775. Park, J.K., 1981. Analysis of multicomponent magnetization of the Little Dal Group, Mackenzie Mountains, Northwest Territories, Canada. J. Geophys. Res. 86, 5134–5146. Park, J.K., 1984. Paleomagnetism of the Mudracked formation of the Precambrian Little Dal Group, Mackenzie Mountains, Northwest Territories, Canada. Can. J. Earth Sci. 21, 371– 375. Park, J.K., Aitken, J.D., 1986. Paleomagnetism of the late Proterozoic Tsezotene Formation of northwest Canada. J. Geophys. Res. 91, 4955– 4970. Park, J.K., Norris, D.K., Larochelle, A., 1989. Paleomagnetism and the origin of the Mackenzie Arc of northwestern Canada. Can. J. Earth Sci. 26, 2194–2203. Pavlov, V.E., Courtillot V., Bazhenov, M.L., Veselovsky, R.V. 2007 Paleomagnetism of the Siberian traps: New data and a new overall 250 Ma pole for Siberia. Tectonophysics 443, 72–92 Pavlov, V.E., Galle, I., 1999. Reconstruction of mutual location of Siberia and Laurentia in the late Mesoproterozoic from paleomagnetic data. Geotectonics 6, 16–28 Pavlov, V.E., Gallet, Y., Petrov, P.Yu., Zhuravlev, D.Z., Shatsillo, A.V., 2002. Uy series and late Riphean sills of the Uchur-Maya area: isotopic and palaeomagnetic data and the problem of the Rodinia supercontinent. Geotectonics 36, 278–292. Pavlov, V.E., Gallet, Y., Shatsillo, A.V., 2000. Palaeomagnetism of the upper Riphean Lakhanda Group of the Uchur-Maya area and the hypothesis of the late Proterozoic supercontinent. Fizika Zemli 8, 23–34. Pickering, K.T., Smith, A., 1995. Arcs and backarcs basin in the Early Paleozoic Iapetus Ocean. Isl. Arc, 4, 1– 67. Pisarevsky, S.A., Komissarova, R.A., Khramov, A.N., 2000. New paleomagnetic result from Vendian red sediments in Cisbaikalia and the problem of the relationship of Siberia and Laurentia in the Vendian. Geophys. J. Int. 140, 598–610. Pisarevsky, S.A., Natapov, L.M., 2003. Siberia in Rodinia. Tectonophysics 375, 221-245. Pisarevsky, S.A., Natapov, L.M., Donskaya, T.V., Gladkochub, D.P., Vernikovsky, V.A., 2008. Proterozoic Siberia: A promontory of Rodinia. Precambrian Res. 160, 66–76.

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Paleomagnetic Evidence for Siberian Plate Tectonics

233

Pogrebitsky, Yu.E. (Ed.), 1982. Geology of Severnaya Zemlya Archipelago. Leningrad, Sevmorgeo, 152 pp. (in Russian). Powell, C.M., McElhinny, M.W., Li, Z.X., Meert, J.G., Park, J.K., 1993. Paleomagnetic constraints on timing of the Neoproterozoic breakup of Rodinia and the Cambrian formation of Gondwana. Geology 21, 889–892. Powell, C.M., Pisarevsky, S.A., 2002. Late Neoproterozoic assembly of East Gondwana. Geology 30, 3–6. Powell, C.M., Roots, S.R., Veevers, J.J., 1988. Pre-breakup continental extension in East Gondwanaland and the early opening of the eastern Indian Ocean. Tectonophysics 155, 261–283. Rainbird R.H., Stern R.A., Khudoley A.K., Kropachev A.P., Heaman L.M. and V.I. Sukhorukov, 1998. U-Pb geochronology of Riphean sandstone and gabbro from southeast Siberia and its bearing in the Laurentia-Siberia connection. Earth Plan.Sci.Lett. 164, 409-420. Reichow, M.K., Saunders, A.D.,White, R.V., Pringle, M.S., Al'Mukhamedov, A.L., Medvedev, A.I., Kirda, N.P., 2002. 40Ar/39Ar dates from the West Siberia basin: Siberia flood basalt province doubled. Science 296, 1846–1849. Renne, P.R., Basu, A.R., 1991. Rapid eruption of the Siberian traps flood basalts at PermoTriassic Boundary. Science 253, 176-179. Renne, P.R., Zhang, Z.C., Richards, M.A., Black, M.T., Basu, A.R., 1995. Synchrony and causal relation between Permian–Triassic boundary crises and Siberian flood volcanism. Science 33, 93–101. Roy, J.L., Robertson, W.A., 1978. Paleomagnetism of the Jacobsville Formation and the apparent polar wander path for the interval 1100–670 m.y. for North America. J. Geophys. Res. 83, 1289–1304. Rushton, A.W.A., Cocks, L.R.M., Fortey, R.A., 2002. Upper Cambrian trilobites and brachiopods from Severnaya Zemlya, Arctic Russia, and their implications for correlation and biogeography. Geological Magazine 139, 281–290. Sears, J.W., Price, R.A., 2000. New look at the Siberian connection: no SWEAT. Geology 28, 423–426. Sengor, A. M. C., B. Natal’in, and V. Burtman, 1993. Evolution of the Altaide tectonic collage and Paleozoic crustal growth in Eurasia. Nature 34, 299–307. Sengor, A.M.C., Natal’in, B.A., 1996. Paleotectonics of Asia: fragments of a synthesis. In: Thomson, M.R.A., Reinemund, J.A. (Eds.), World and Regional Geology Series. Cambridge Univ. Press, Cambridge, 486–666 Shadaev, M.G., Posokhov, V.F., Drobetskoi. E.R., 1992. New data on the age of the Ichetui suite in western Transbaikalia (Rb-Sr and K-Ar data). Russ. Geol. Geophys. 33(5), 32– 35. Sharma, M., 1997. Siberian traps. In: Mahoney, J.J., Coffin, M.F. (Eds.), Large Igneous Provinces: Continental, Oceanic, and Planetary Flood Volcanism, Geophysical Monograph, vol. 100, 273–295. Shatsillo, A.V., Didenko, A.N., Pavlov, V.E., 2005. Two competing Paleomagnetic directions in the Late Vendian: New data for the SW Region of the Siberian Platform. Russ. J. Earth Sci. 7(4), 3–24. Simonov, V.A., Dobretsov, N.L. and M.M. Buslov, 1994. Boninite series in structures of the Paleo-Asian Ocean. Russ. Geol. Geophys. 35(7-8), 182-199.

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Sklyarov, E.V., Gladkochub, D.P., Mazukabzov, A.M., Donskaya, T.V., and A.M. Stanevich, 2002 Geological complexes in the margin of the Siberian Craton as indicators of the evolution of a Neoproterozoic Supercontinent Russ J Earth Sci. 4(3), 171–186. Sklyarov, E.V., Gladkochub, D.P., Mazukabzov, A.M., Menshagin, Y.V., Watanabe, T., Pisarevsky, S.A., 2003. Neoproterozoic mafic dike swarms of the Sharyzhalgai metamorphic massif (southern Siberian craton). Precamb. Res. 122, 359–376. Smethurst, M.A., Khramov, A.N., Torsvik, T.H., 1998. The Neoproterozoic and Palaeozoic palaeomagnetic data for the Siberian platform: from Rodinia to Pangea. Earth Sci. Rev. 43, 1–24. Sovetov, Yu.K., Komlev, D.A., 2005. Tillites at the base of the Oselok Group, foothills of the Sayan Mountains, and the Vendian lower boundary in the southwestern Siberian Platform. Strat. Geol. Corr. 13, 337–366. Sovetov, Yu.K., Blagovidov, V.V., Luchinina, V.A., Romashko, A.I., 2000. Vendian sediments on the Western Yenisei Ridge. Dokl. Earth Sci. 372, 630–635. Symons, D.T.A., 1992. Paleomagnetism of the Keewanawan Chipman Lake and Seabrook Lake carbonatite complexes, Ontario. Can. J. Earth Sci. 29, 1215–1223. Symons, D.T.A., Chiasson, A.D., 1991. Paleomagnetism of the Callander Complex and the Cambrian apparent polar wander path for North America. Can. J. Earth Sci. 28, 355–363. Timofeev, V.Yu., Ardyukov, D.G., Kazansky A.Yu., Metelkin D.V., Boyko E.V., Bragin, V.Yu., 2008. Siberian platform rotation at different geological epochs (GPS and paleomagnetic data) In: Proceedings of the Fourth International Exhibition and Scientific Congress “GEO-Siberia”, v.3, part 2, Novosibirsk, 279-284. (in Russian). Torsvik, T.H., Smethurst, M.A., Meert, J.G., Van der Voo, R., McKerrow, W.S., Sturt, B.A., Brasier, M.D., Walderhaug, H.J., 1996. Continental breakup and collision in the Neoproterozoic and Paleozoic — a tale of Baltica and Laurentia. Earth Sci. Rev. 40, 229– 258. Uflyand, A.K., Natapov, L.M., Lopatin, V.M., Chernov, D.V., 1991. On the tectonic nature of Taimyr. Geotectonics, 25 (6), 76– 93. Van der Voo, R., 1990. The reliability of paleomagnetic data. Tectonophysics 184, 1– 9. Van der Voo, R., Levashova, N.M., Skrinnik, L.I., Kara, T.V., Bazhenov, M.L., 2006. Late orogenic, large-scale rotations in the Tien Shan and adjacent mobile belts in Kyrgyzstan and Kazakhstan. Tectonophysics 426, 335–360 Vernikovskaya, A.E., Vernikovsky, V.A., Sal’nikova, E.B., Kotov, A.B., Kovach, V.P., Travin, A.V., Palessky, S.V., Yakovleva, S.Z., Yasenev, A.M., Fedoseenko, A.M., 2003. Neoproterozoic postcollisional granitoids of Glushikha complex, Yenisei Ridge. Petrologiya 11 (1), 53–67. Vernikovsky, V.A., 1996. Geodynamic Evolution of Taimyr Folded Area. Novosobirsk Publ. SB RAS. 203 pp. (in Russian). Vernikovsky, V.A., Neimark, L.A., Ponomarchuk, V.A., Vernikovskaya, A.E., Kireev, A.D., Kuzmin, D.S., 1995. Geochemistry and age of collision granitoids and metamorphites of the Kara microcontinent (Northern Taimyr). Russ.Geol. Geophys. 36 (12), 50– 64. Vernikovsky, V.A., Salnikova, E.B., Kotov, A.B., Kovach, V.P., Travin, A.V., Yakovleva, S.Z., Berezhnaya, N.G., 1998b. The age of postcollision granitoids of the North Taimyr: U–Pb, Sm–Nd, Rb–Sr and Ar–Ar data. Dokl. Earth Sci., 363 (9), 1191–1196.

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Vernikovsky, V.A., Vernikovskaya, A.E., 2001. Central Taimyr accretionary belt (Arctic Asia): Meso-Neoproterozoic tectonic evolution and Rodinia breakup. Precamb. Res., 110, 127– 141. Vernikovsky, V.A., Vernikovskaya, A.E., Chernykh, A.I., Melgunov, M.S., 1996. Petrology and geochemistry of Taimyr Riphean ophiolites. Russ. Geol. Geophys. 37(1), 113–129. Vernikovsky, V.A., Vernikovskaya, A.E., Nozhkin, A.D., Ponomarchuk, V.A., 1994. Riphean Ophiolites of the Isakov belt (Yenisey Ridge). Russ. Geol. Geophys. 35 (7– 8), 146– 156 Vernikovsky, V.A., Vernikovskaya, A.E., Pease, V.L., Gee, D.G., 2004. Neoproterozoic orogeny along the margins of Siberia. In: Gee, D.G., Pease, V.L. (Eds.), The Neoproterozoic Timanide orogen of Eastern Baltica. Geol. Soc. London Mem. 30, 233– 247. Vernikovsky, V.A., Vernikovskaya, A.E., Sal’nikova, E.B., Kotov, A.B., Chernykh, A.I., Kovach, V.P., Berezhnaya, N.G., Yakovleva, S.Z., 1999. New U-Pb data on the formation of the Predivinsk paleoisland-arc complex (Yenisei Range). Russ. Geol. Geophys. 40 (2), 255–259. Vernikovsky,V.A.,Vernikovskaya, A.E. 2006 Tectonics and evolution of granitoid magmatism in the Yenisei Ridge. Russ. Geol. Geophys. 47(1), 32–50. Vernikovsky,V.A.,Vernikovskaya, A.E.,Kotov, A.B., Sal’nikova, E.B.,Kovach, V.P., 2003. Neoproterozoic accretion-collisional events on the western margin of the Siberian Craton: new geological and geochronological evidence from the Yenisey Ridge. Tectonophysics 375, 147–168. Veselovsky, R.V.,Gallet,Y., Pavlov,V.E., 2003. Paleomagnetismof traps in the Podkamennaya Tunguska and Kotuy River valleys: implications for the post-Paleozoic relative movements of the Siberian and East European platforms. Phys. Solid Earth 39 (10), 856–871. Voronov, P.S. (Ed.) 1997. Role of shear tectonics in the lithosphere structure of the Earth and terrestrial planets. Nauka, St.Petersburg, 591 p. (in Russian) Vorontsov, A.A., Yarmoluyk, V.V., Ivanov, V.G., Smirnov, V.N., 1997. Late Mesozoic magmatism of the Borgoi Depression in Western Transbaikalia (age and composition). Russ. Geol. Geophys. 38(8), 1345–1351. Watson, G.S. and Enkin, R.J., 1993. The fold test in paleomagnetism as a parameter estimation problem, Geophys. Res. Lett., 20, 2135–2137. Watts, D.P., 1981. Paleomagnetism of the Fond du Lac formation and the Eileen and Middle River sections with implications for Keewanawan tectonics and the Grenville problem. Can. J. Earth Sci. 18, 829–841. Weil, A.B., Van de Voo, R., Mac Niocaill, C., Meert, J.G., 1998. The Proterozoic supercontinent Rodinia: paleomagnetically derived reconstruction for 1100 to 800 Ma. Earth Planet. Sci. Lett. 154, 13–24. Westphal M., Gurevich E.L., Samsonov B.V., Feinberg H., Pozzi J.P. 1998 Magnetostratigraphy of the Lower Triassic volcanics from deep drill SG in Western Siberia: evidence of long-lasting Permo-Triassic activity. Geophys. J. Int. 134, 254-266. Wingate, M.T.D., Giddings, J.W., 2000. Age and palaeomagnetism of the Mundine Well dyke swarm, Western Australia: implications for an Australia-Laurentia connection at 755 Ma. Precamb. Res. 100, 335–357.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

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Wingate, M.T.D., Pisarevsky, S.A., Evans, D.A.D., 2002. Rodinia connections between Australia and Laurentia: no SWEAT, no AUSWUS? Terra Nova 14, 121–128. Yarmolyuk, V.V., Kovalenko, V.I., 2001. Late Riphean breakup between Siberia and Laurentia: Evidence from intraplate magmatism, Dokl. Earth Sci. 379, 525–528. Yarmolyuk, V.V., Vorontsov, A.A., Kovalenko, V.I., Zhuravlev, D.Z., 1997. Isotopic inhomogeneity of source of Late Paleozoic intraplate magmatism in Central Asia. Russ. Geol. Geophys. 38, 1178–1183. Zhamoitsina, L.G., 1997. Mesozoic basalt volcanism and zeolite mineralization of Western Transbaikalia (by example of the Margintui volcanic field). Russ. Geol. Geophys. 38(8), 1352–1361. Zhao, X., Coe, R.S., Zhou, Y.X., Wu, H.R. & Wang, J., 1990. New palaeomagnetic results from northern China: collision and suturing with Siberia and Kazakhstan. Tectonophysics, 181, 43–81. Zhao. X., Coe. R.S., Gilder. S.A., Frost. G.M., 1996. Palaeomagnetic constrains on the palaeogeography of China: implications for Gondwanaland. Austr. J. Earth Sci. 43, 643– 672. Zolotukhin V.V., Al’mukhamedov A.I. 1988 Traps of Siberian Platform. In: Macdougall, J.D. (Ed.), Continental Flood Basalts. Kluver Academic, Dordrech, 273- 310. Zolotukhin, V.V., 1998. The heat effect of trap injection on the Siberian Platform in the context of the plume concept. Russ. Geol. Geophys. 39, 1061–1065. Zonenshain, L.P., Kuzmin, M.I., Natapov, L.M., 1990. Geology of the USSR: a plate tectonic synthesis. Geodynamic Monograph. Amer. Geoph. Union, Washington Ser. 21, 242 pp. Zorin, Yu.A., 1999. Geodynamics of the western part of the Mongolia.Okhotsk collisional belt, Trans-Baikal region (Russia) and Mongolia. Tectonophysics 306, 33-56

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In: Geomorphology and Plate Tectonics Editors: D. M. Ferrari, A. R. Guiseppi

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Chapter 9

GEODYNAMICS OF INDIAN FREE-BOARD: ARCHEAN-PROTEROZOIC COLLISION ZONES AND UNDERLYING LITHOSPHERE AND ITS RAPID DRIFT D.C. Mishra* and M. Ravi Kumar National Geophysical Research Institute, Hyderabad, India

ABSTRACT

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Bouguer anomaly map of India has provided several medium and short wavelength anomalies that are discussed vis-à-vis regional and local tectonics. Fold Belts signifying Archean-Proterozoic collision zones similar to present day collision zones like Himalayas are characterized by linear gravity highs due to thrusted high density rocks flanked by gravity lows due to low density Proterozoic metasediments on one side and granitic intrusions and crustal thickening on the other side representing foreland basins and subduction related magmatism, respectively. These characteristics have helped to divide the Indian Shield under various cratons and fold (mobile) belts and probable directions of their convergence during their collision. There have been large scale rifting and convergence in Northern and Eastern India during Paleo and Meso-Neo Proterozoic periods, respectively while the western and southern India is dominated by similar activities during Neo Archean-Paleo Proterozoic period. Most of the Proterozoic collision of Indian cratons were direct giving rise to large scale thrusts except between Western and Eastern Dharwar cratons that was oblique and soft producing only a shear zone. Direction of convergence between various cratons of Indian Shield during ArcheanProterozoic period is all most opposite to the present day convergence across Himalayan Fold and Thrust Belts that is in conformity with the direction of movement based on paleomagnetic studies. Archean-Proterozoic fold belts being along the margins of large cratons probably help them to maintain their relative elevation in spite of millions of years of erosion and isostatic uplift. Large wavelength gravity anomalies are related to the present day lithospheric structures that suggest the average depth of lithosphere under Indian continent as 160-180 km that reduces to 140 km under lithospheric upwarp along the Himalayan front. The lithospheric mantle is primarily occupied by low density rocks of 3250 kg/m3 compared *

Correspondense to: E-Mail: [email protected]

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D.C. Mishra and M. Ravi Kumar to surrounding rocks of 3300 kg/m3. These rocks may represent subducted Tethyan/Indian lithosphere and is supported from high velocity in seismic tomography. These low density rocks appear to be responsible for uplift of S. Indian Shield and present day fast movement of the Indian plate due to their buoyancy. It is further aided by the absence of high velocity keel of the Indian cratons as suggested from receiver function analysis. Gravity highs of lithospheric mantle in NW and SE India may represent the thinning of lithosphere or mafic intrusives during the break up of the Indian plate from Gondwana land caused by plumes. The part of lithospheric and crustal gravity highs in northern India under Ganga basin south of Himalayas can be attributed to lithospheric and crustal upwarp and associated intrusives due to flexure of the Indian plate. Spectral analysis of CHAMP satellite magnetic data also suggest a magnetic discontinuity at a depth of 150-160 km that represent the presence of cold subducted Indian/Tethyan lithosphere at this level where temperature is lower compared to the Curie point geotherm.

Keywords: Archean-Proterozoic Collision, Lithosphere, Indian plate, Spectrum, Gravity, CHAMP satellite magnetic

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1. INTRODUCTION Forces that are important on regional scale of plates and are significant for plate tectonics mostly operate in the lithosphere and below it. It is, therefore important to understand the nature of rock types in this section. Indian plate primarily consist of Indian continent and surrounding oceans that are relatively young formed after the break up of India from Antarctica at about 120-118 Ma. However, the Indian continent is composed of several cratons and fold belts (mobile belts) that belong to Archean-Proterozoic period. Therefore, though the geodynamics of Indian plate starts from the break up of Gondwanaland but its history is not complete without referring the cratons and fold belts of Indian continent and the processes that formed them. Plate tectonics was largely developed to account for observables in oceans like Sea floor spreading magnetic anomalies and mountain building processes over adjoining continents along subduction zones. It, therefore firstly accounted for about 200 Ma that is the oldest reported sea floor magnetic anomalies and age of the ocean. However, continents being much older (Archean-Proterozoic period) required either another theory or extension of the same plate tectonics theory with some variant to explain various processes observed over them. In this regard the first effort to extend plate tectonics backwards in times during Archean-Proterozoic period was made only after a few years of discovery of plate tectonics based on rock types and structures specially in regard to Archean greenstone belts (Windley, 1973; Burke et al., 1973, Tarney et al., 1976). The most important signatures of Archean-Proterozoic convergence and their signatures are two fold, namely (i) Exposed up thrusted lower crustal mafic/ultramafic rocks in the collision zones or at shallow depths in upper crust delineated from high density, high seismic velocity and high conductivity of these rocks and (ii) Exposed arc and back-arc magmatic rocks within the present day cratons towards the subducted side in association with crustal thickening and dipping reflectors in the upper mantle. These two characteristics invariably gave rise to paired gravity anomalies, viz high due to the first kind of signatures and low due to second type. Gibb and Thomas (1976) analysed gravity anomalies from several cratons and

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Geodynamics of Indian Free-Board: Archean-Proterozoic Collision Zones

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.

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suggested that highs will be observed over younger Proterozoic rocks while lows are observed over older Archean rocks. Fountain and Salisbury (1981) also emphasized the occurrences of paired gravity anomalies over known Archean-Proterozoic collision zones from different parts of the world. Mishra et al. (2000) analysed gravity anomalies from various parts of the Indian Shield and suggested that linear gravity highs of small wavelength characterize the Proterozoic fold belts caused by high density intrusives (thrusts) while (medium-large wavelength) lows are observed over the adjoining Archean cratons due to metasediments and related magmatic intrusions and back arc basins. It has also been suggested that initially during Archean period, cratons must have been smaller that grew due to accretion of rocks associated with collision and collision related activities.

Figure 1a. Tectonic map of India showing various cratons and fold belts (modified after ONGC, 1968) with arrows indicating direction of convergence during geological periods. Thick arrows in north (SWNE) indicate Cenozoic convergence across Himalayan Fold Belt while thin one indicates ArcheanProterozoic convergence between various cratons.

Based on magnetic anomalies in the Indian Ocean, the inferred speed of the Indian plate is about 4.8 cm/yr (Royer and Patriat, 2002) that is one of the fastest among the various plates. The cause for this fast speed of the Indian plate has been a matter of great speculation among the geoscientists that has been attributed to thin lithosphere caused by plumes by Kumar et al. (2007) while Raval (1993) attributed it to thick lithosphere driven by plumes and

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Negi et al. (1987) attributed it to thin lithosphere due to frictional heating. Based on S-wave receiver function analysis, Kumar et al. (2007) have estimated lithospheric thickness of about 100 km while Priestley et al. (2006, 2008) based on surface wave form tomography suggested a thickness of about 160 km under Indian continent increasing to about 320 km under Tibet. Based on thick lithosphere under Tibet, McKenzie and Priestley (2008) suggested that Tibet may be a craton in making. Kieselev et al. (2008) suggested crustal thickness of 31 km under Eastern Dharwar Craton (EDC) and 55 km under Western Dharwar Craton (WDC) (Fig 1a) and did not notice any change in S-wave velocity between 50 and 250 km. They also suggested absence of high velocity keel under Indian cratons that characterizes most of the cratons world over. Li et al. (2006) provided tomographic image below Tibet suggesting a high velocity from 80 km upto 300 km. They also suggested high velocity zone under Indian continent from 60 km to 200 km that represents the lithosphere. However, the high velocity is further noticed below 600 km (Lebedev and Van der Hilst, 2008) that represents the subducted Tethyan lithosphere. In light of these controversies about Indian lithosphere and subducted Tethyan lithosphere, large wave length gravity anomalies observed over India, are analysed to obtain density characteristics of rocks in lithosphere and its consequences.

2. SPECTRAL ANALYSIS OF GRAVITY FIELD

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Spectral analysis of potential fields (Mishra, and Pedersen, 1982; Fedi et al., 1997) can be used to obtain the average depth to the sources and the corresponding frequency bands can be used to separate the observed fields in to different components originating from different levels. Accordingly the transform of the observed gravity fields (g(k)) for a layered model with relief can be expressed as g (k) = 2πGρ.

∑ exp – ⏐k⏐ z . Δz (k) k

(1)

Where z is the average depth and ρ is the density of the layer. Δz(k) is the transform of the relief of the layer with ⏐k⏐ representing the frequencies given by k = 1, 2 …. n/2 or n-1/2 depending on whether the number of observations (n) is odd or even numbers. In case the relief of the layer is less than its average depth and uncorrelated, Δz (k) = 1 and therefore ln (g (k)) versus k provides straight line segments with slopes equal to the average depth of relief of the layer. However model studies (Mishra and Pedersen, 1982) have shown that spectral depths are 10-15% over estimate of the average depth of the relief and therefore, provide the upper bound of depth estimates. In case of two dimensional maps, k2 = kx2 + ky2 where kx and ky are frequencies in x and y directions and therefore the two dimensional computed spectrum is averaged radially to provide radial spectrum versus combined frequencies k. In case of multilayered cases, they are separated in different wave bands with respective linear segments that can be used to estimate average depths and separate the observed field in groups by corresponding wave band filters (Naidu and Mathew, 1998).

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Figure 1b. A schematic representation of cratons and fold belts of Indian Peninsular Shield. Cratons: BC = Bhandara-Bastar Craton, BKC = Bundekhand Craton, DC = Dharwar Craton, EDC = Eastern Dharwar Craton, SC = Singhhum Craton, WDC = Western Dharwar Craton, Fold Belts: ADFB = Aravalli-Delhi Fold Belt, EGFB = Eastern Ghat Fold Belt, SFB = Satpura Fold Belt, CGGC = Chotanagpur Granite Gneisic Complex. Thrusts/Shear Zones: CIS = Central Indian Shear, CSZ = Cauvery Shear Zone, DT = Delhi Thrust, GBF = Great Boundary Fault, GS = Gangavalli shear: NE extension of PCSZ, MBSZ = Moyar-Bhavani Shear Zone, MS = Mettur Shear: NE extension of MBSZ, NPSZ = North Purulia Shear Zone, NSL = Narmada-Son Lineament, PCSZ = Palghat-Cauvery Shear Zone, SPSZ = South Purulia Shear Zone, SZ = Shear Zone between WDC and EDC, TL = Tapti Lineament, TZ = Transition Zone. Geological Provinces/Basins: BG = Bijawar Group of rocks, CB = Cuddapah Basin, CL = Closepet Granite, DVP = Deccan Volcanic Province, GB Godavari Basin and MKG = Mahakoschal Group of rock, SM = Sausar Meta-sediments, SGT = Southern Granulite Terrain, SRMB = South Rewa Mahandadi Basin and VB = Vindhyan Basin. Periods: APt1 = Neoarchean-Paleoproterozoic, Pt1 = Paleoproterozoic, Pt2 = Mesoproterozoic and Pt3 = Neoproterozoic. Profiles: Profile I = Nagaur (NA)-Jhalawar (JH), Profile II = Mungwani (MU)-Rajnandgaon (RG), Profile III = Hirapur (H)-Mandla (M), Profile IV = Across Singhbum Thrust and Craton, Profile V = Bhandara-Bastar Craton to Dharwar Craton across Godavari Proterozoic Basin, Profile VI = Kavali (KA)-Udipi (UD), Profile VII = Kuppam (KU)-Palani (PA) extended towards north and to the coast across H13 and L14, respectively (Fig 2b), NB = Northern Block, north of PCSZ and SB = Southern Block, south of PCSZ.

2. GEOLOGY AND TECTONICS The observed gravity field is controlled to a great extent by geology and tectonics. Fig 1a is a simplified tectonic map of India. The northern part of India is occupied by Himalayan

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Fold Belt and associated thrusts. The Himalayan fold belt consist of several thrusts such as Main Central Thrust (MCT), Main Boundary Thrust (MBT) and Himalayan Frontal Thrust (HFT) from north to the south formed approximately during 20 Ma, 10 Ma and 3-2 Ma, respectively due to collision between the Indian and the Eurasian plates. MCT is characterized by crystalline basement rocks that are thrusted over Proterozoic metasediments along MBT which are thrusted over Paleozoic and Mesozoic sediments. HFT has thrusted Quaternary sediments over alluvium of Ganga basin that represents a foreland basin of Himalayan orogeny. Further north is the Indus Tsangpo Suture Zone (ITSZ) between the Indian and the Eurasian plates and Tibet is a part of the latter. Ganga basin is a foreland basin of Himalayan orogeny with thick sediments of 3-5 km overlying the basement. Aravalli-Delhi and Satpura Fold Belts of Proterozoic period (Fig 1a & b) occupy the western and the central parts, respectively with Ganga and Vindhyan basins lying in between them. The NE-SW trends of the northern part of India (Aravalli-Delhi Fold Belt-ADFB) changes to NW-SE in the southern part (Dharwar Craton) across Satpura (ENE-WSW) Fold Belt (SFB). Important geological units of ADFB and SFB and of the Bhandara and the Singhbhum cratons and their ages are described in Table 1 that also serves a comparison between them. South of 15oN the structural trends are N-S which are abetted against NE-SW trend at about 12-13oN changing to E-W at about 10-11oN. These structural trends define the major tectonic units. The Eastern and the Western Ghats occupy the two coasts lines, the former representing the Proterozoic fold belt. It is interesting to note that Archean-Proterozoic fold belts in the tectonics are reflected as high lands. The Southern Indian Shield is occupied by Archean cratons with Proterozoic and Gondwana basins in between (Fig 1b). They are described in detail below while describing their gravity anomalies.

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3. BOUGUER ANOMALY MAP OF INDIA The terrain corrected Bouguer anomaly map of India prepared based on uniform distribution of data at 5.0 km grid interval representing complete Bouguer anomaly with accuracy better than ±1.5 mGal (GSI-NGRI, 2006) is given in Figs 2a & b. Bouguer anomalies are largely positive (Figs 1a & b and 2a & b) over fold belts such as Aravalli, Satpura and Eastern Ghat that are high lands in the Indian continent indicating thinner crust under them compared to isostatically balanced crust based on topography. Short wavelength gravity highs are caused by shallow high density rocks. Bouguer anomaly is mostly negative over Himalayas (L1) and South Indian Shield (L8) including Western Ghats indicating thick crust due to isostatic compensation of topography. Fold Belts being largely occupied by Proterozoic rocks flanked by cratons will be examined for signatures of Archean-Proterozoic collision zones that are discussed below in detail. The various Bouguer anomalies described below with respect to tectonics and geology (Fig 1a & b) are shown in Fig 2a & b as H and L indicating gravity highs and lows with following numbers referring to individual anomalies.

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Table 1. Some Important Tectonic Events and Intrusives of ADFB and SFB and Adjoining Cratons (Fig 1b) Age

ADFB (Sinha Roy, 1988 and Choudhary et al., 1984)

NeoProerozoic

Post Delhi magmatism: Einpura grnite and Malani volcanics: 0.80.7 Ga Back arc basins with bimodal volcanics: 0.90.8 Ga End of Delhi orogeny: 1.0 Ga Deformation and thrusting of Delhi rocks: 1.1 Ga Delhi rifting and Delhi supergroup of rocks: 1.5 Ga

MesoProterozoic

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PaleoProterozoic

Archean

End of Aravalli orogeny: 1.6 Ga Granite of north Delhi fold belt and base metal mineralization: 1.7-1.6 Ga Darwal and Amet granite: 1.9-1.7 Ga Sandmata lower crustal granulite rocks, thrusting: 1.9-1.8 Ga Aravalli rifting and supergroup of rocks: 2.2-2.1 Ga Berach granite: 2.5 Ga Untala and Gingla granite: 2.9 Ga Banded gneissic complex: 3.5 Ga

SFB: Central Part of SFB and Bastar Craton (Sarkar et al. 1981 and Jain et al. 1991)

SFB: Eastern Part and Singhbhum Craton: (Acharyya, 2003b)

End of Sausar orogeny: 1.0 Ga Southern granulite rocks: 1.0Ga Mangikota volcanics: 1.0 Ga Kairagarh volcanics: 1.4 Ga Sausar meta sediments and gneisses/migmatite complex 1.5 Ga

End of Singhbhum orogeny: 0.9-1.0 Ga Southern granulite belt in CGGC Gangpur granite intrusive 1.0 Ga Mayurbhanj granite 1.2 Ga Chankradarpur granitegneiss 1.5-1.1 Ga Anorthosite gabbro 1.5 Ga Ultramafic intrusions northern granulite belt in CGGC 1.6-1.5 Ga Kohan group 1.6-1.5 Ga Dalma-ChandeliDhanjori volcanics. Similar to back arc basins 1.7 Ga

End of Mahakoshal orogeny: 1.6 Ga Dormation of Mahakoshal rocks and northern granulite rocks: 1.6 Ga Sakoli and Nandagon bimodal volcanics of back arc type: 2.2 Ga Dongargarh and Malanjkhand K-granite, Island ar type: 2.3 Ga Granite intrusions: 2.41.6 Ga Mahakoshal group of rocks: 2.4 Ga Unclassified granite and gneisses (Amgaon, Sukma etc.): 3.0-3.5 Ga

Dhaibhum stage Chaibasa stage

Singhbhum granite (2.95 Ga) Older metamorphic group (3.3 Ga)

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Figure 2a and b. Complete Bouguer anomaly map showing gravity highs and lows marked as H and L, respectively and the following numbers indicate the individual anomalies associated with different tectonic units as described in the text (a) North of 20oN and (b) South of 20oN.

4.1. Cenozoic Tectonics in Northern Part The northern part of India and its tectonics is largely controlled by collision of the Indian and the Eurasian plates at about 50 Ma with compressional forces in SW-NE direction (Royer

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and Patriat, 2002). This collision has produced Himalayan Fold Belt with several thrusts that gave rise to high mountains of Himalayas and Ganga basin in front of it as a foreland basin. 1. Himalayas (L1, H1; Fig 2a) a) It is characterized by regional gravity lows (L1) (-250 to -350 mGal) with increasing elevation indicating isostatic compensation related to crustal thickening caused by the collision of the Indian and the Eurasian plates. However, isostatic anomaly along a profile (Banerjee and Satya Prakash, 2003) being high over Himalayas and low over Himalayan fore deep and S. Tibet suggest under compensation in the case of former and over compensation in latter cases that makes Himalayan front sandwiched between two over compensated sections considerably active both tectonically and seismically. b) Relative short wavelength Bouguer anomaly highs (H1) of 10 to 20 mGal (Fig 2a) along Himalayan Fold Belt and Indus Tsangpo Suture Zone (ITSZ) between two plates suggest high density thrusted rocks along them. These are SW verging thrusts indicating SW-NE convergence (Fig 1a). It may be noted that these small wavelength gravity highs are better reflected in free air anomaly (Mishra et al., 2008) compared to Bouguer anomaly due to the effect of crustal thickening in the latter that produces gravity lows which over shadows the highs due to shallow bodies. However, the gravity low, L1 due to crustal thickening is better reflected in Bouguer anomaly map compared to free air anomaly suggesting the importance of both maps for specific purposes.

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2. Ganga Basin (L2, H2; Fig 2a) a) Bouguer anomalies are negative with minimum value of -150 to -200 mGal in a plain region with elevation of a few hundred meters. Therefore, these anomalies are primarily caused by shallow sources of 3-5 km thick sediments. b) There are basement ridges and depressions shown by relative gravity highs (H2) and lows (L2), respectively which in most cases are extensions of structures from Indian Peninsular Shield towards the north. Gravity high, H2 for example, represents a basement ridge which is an extension of basement rocks under western margin of the Vindhyan basin (L5). The examination of gravity anomalies of Himalayas that represent an active present day collision zone between the Indian and the Eurasian plates suggest that it is characterized by linear gravity highs due to thrusted high density rocks with adjoining lows towards the north and the south caused by crustal thickening and sediments of the foreland basin, respectively. The same criteria can be used to decipher Archean-Proterozoic collision zones between cratons. However, with passing time (on million years scale), the crustal thickness decreases due to constant erosion and uplift and so is the gravity low caused by it. Therefore, the ratio of gravity high to low is much more (1-2) in case of Archean-Proterozoic collision zones compared to the present day orogenic belts (0.1-0.01) as in case of Himalayas and Tibet.

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4.2. Archean-Proterozoic Collision Zones of Indian Shield Indian Shield consists of several Archean cratons and intervening Proterozoic fold (mobile) belts. Gravity signatures due to Archean Proterozoic Fold Belts are examined with reference to Fig 1b and Figs 2a & b. As described above for Himalayas, gravity highs over fold belts and adjoining lows due to crustal thickening and foreland basins along with other geophysical/geological data sets available from these regions shall be examined in this regard.

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(i) Aravalli-Delhi Fold Belt (ADFB, H3) and Western Rajasthan (H4): a) It is characterized by Paleo-Meso-Proterozoic rocks (Fig 1b; Table 1). Based on geological records, Sinha Roy (1988) suggested two stages of convergence in this section viz. Aravalli and Delhi orogenies during Paleo and Meso-Proterozoic periods. It shows gravity highs both in free air anomaly (∼50 mGal) and Bouguer anomaly (∼10 mGal) with high elevation. Gravity highs are, therefore, caused by shallow high density sources. b) Crustal model along a profile Nagaur-Jhalawar (Profile I, Fig 1b; Mishra et al, 2000) constrained from seismic section (Tewari et al., 1997) suggest high density ophiolite rocks along the western gradient and a high density body in the lower crust under Delhi Groups of rocks towards the west responsible for the gravity high (H3). The eastern gradient of this gravity high coincides with a east verging thrust (Zahazpur Thrust) and most of the base metal mineralized zones of this region coincide with this gradient (Prasad et al., 1999). This indicates that this thrust has acted as conveyor belt for these minerals. Such thrusts in fold belts provide important regional setting for mineralized zones. c) The linear gravity lows west of the gravity high (H3) are caused by magmatic rocks of Erinpura granite of Neo-Proterozoic period and several small back arc basins with bimodal volcanics in between that suggest a Meso-Neo-Proterozoic rifting and collision between Bundelkhand craton towards the east and western Rajasthan block with convergence and subduction from the east to the west as shown in Fig 1a by thin arrow east of ADFB.. d) Western Rajasthan shows semicircular gravity highs both in free air (∼80 mGal) and Bouguer anomaly (∼50 mGal) indicating shallow high density rocks. Similar gravity highs have also been reported from the eastern Pakistan under Indus fore deep that can be attributed to mafic intrusives due to crustal upwarp caused by flexure of the Indian plate. Their connection to gravity highs of Saurashtra, Kutch and offshore also indicate that some of them might be related to the break up of Indian plate from Africa during Jurassic period that gave rise to several known Mesozoic basins in this region.

(ii) Satpura Fold Belt (SFB, H6 - H8) a) The SFB is characterized by rocks of Paleo-Neo Proterozoic period (Fig 1b, Table 1) and shows gravity highs both in free air and Bouguer anomaly with increasing elevation that indicate lack of isostatic compensation and gravity

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anomalies are caused by high density rocks in the upper crust. Modelling this anomaly along Profile II (Fig1b) suggested a high density body at a depth of 810 km (Mishra et al., 2000) coinciding with a high conductive body (Sarma et al., 1996) that suggested lower crustal rocks at shallow depth in this section and crustal thickening southwards under Bhandara craton. b) Seismic profile Hirapur-Mandla (Profile III, Fig 1b) across SFB (Kaila et al., 1987) being studied extensively was extended further north and south to cover Bundelkhand and Bhandara cratons, respectively and gravity field along this profile was modeled (Fig 3, Arora et al., 2007). It provided a relatively shallow crust (40-41 km) under SFB increasing to about 44 km on either sides with several high density intrusives (G1-G3) under exposed Deccan trap. They are associated with Mahakoshal Group of Rocks between the North and the South Narmada Faults (NSL, Fig 1b) along northern margin of the SFB (G1); upper crustal intrusive under SFB (G2) and along Central Indian Shear (G3). The high density intrusive, G1 is supported from high velocity in seismic section as a horst (Sain et al., 2000) which suggest thrusted lower crustal rocks. Seismic section does not extend to G2 and G3. G1 and G2 are also supported from high conductivity (Gokaran et al., 2001). Exposed granulite rocks along CIS suggest that high density rocks of G3 may represent lower crustal rocks. c) North verging thrusts G1, G2, G3 and island arc type magmatism of Bhandara craton (Yedekar et al., 1990) suggest collision of Bundelkhand and Bhandara cratons in the central part of the SFB with convergence and subduction from the north to the south as shown in Fig 1a north of the SFB. The Bijawar (H5) and Mahakoshal Group of rocks (northern part of H6, Fig 2) showing high density suggest mafic and ultramafic rocks which represent rifting phase of Bundelkhand craton during Paleo Proterozoic period (Table 1) and Vindhyan sediments of Meso-Neo Proterozoic were deposited on the platform formed due to this rifting as a foreland basin during the convergence similar to present day Ganga basin. Mahakoshal Group of rocks occupied a rifted margin which were subsequently uplifted that may be related to convergence and collision phase. Occurrences of porcellanite in the lower part of the Vindhyan basin also suggest igneous activities during this period (Chakraborti et al., 2007) which is a common feature of rifted margins. d) Mishra (2006) suggested the extension of this collision zone along central part of the SFB towards the east upto Singhbhum craton (H17 and L17) and towards the west upto the west coast of India (H7) with Singhbhum thrust and Tapti lineament as plausible sutures, respectively in these sections. Table 1 provides the comparison of rock types of Singhbhum craton with central part of the SFB and ADFB indicating similarity between them. It is indicated by similar nature of gravity anomalies with gravity highs over the Singhbhum thrust (H17) and the Tapti lineament (H7) and gravity lows towards south (L17 & L8) suggesting high density lower crustal rocks and crustal thickening as in the central part. The gravity anomalies of ADFB and SFB are joined in the western part forming an arcuate shaped collision zone between Bundelkhand craton in center and western Rajasthan towards the west and Dharwar-Bhandara-Singhbhum cratons towards the south and NE-SW convergence between them (Fig 1a). Rajasekhar and

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Mishra (2008) have suggested the extension of the SFB further eastward upto Shillong Plateau (H8) that has been considered to be part of SFB extending upto Eastern Himalayan front. Table 1 shows that there may have been two stages of rifting and convergence along the ADFB and the SFB related to Aravalli and Delhi orogenies and Mahakoschal and Sausar orogenies related to Central Indian shear/suture, respectively

Figure 3. Gravity profile across SFB (Profile III, Fig 1b) and computed crustal density model showing exposed geology and important tectonics at the top of the model and causative sources below it. BCBundelkhand Craton, VS-Vindhyan Sediments, B-Bijawar Group of rocks exposed in adjoining section, NNF-Narmada North Fault, NSF-Narmada South Fault, MK-Mahakoshal Group of rocks, DT-Deccan Trap, SMB-Satpura Mobile (Fold) Belt, Gn-Gneisses, CIS-Central Indian Suture, G1, G2 represent subsurface high density lower crustal rocks and G3 is exposed lower crustal granulitic rocks along CIS.

(iii) Godavari Proterozoic Basin (L7 and Adjoining Gravity Highs) a) This section is characterized by Gondwana (Permian-Triassic) sediments (Raju, 1986) underlain by Proterozoic metasediments of Meso Proterozoic period (Rao, 1987) that are exposed on either sides of the Central Godavari basin (Fig 1b). b) North of the exposed Proterozoic rocks is the Bastar Craton that consists of several basins of Meso Proterozoic period. The contact of Bastar Craton with the Proterozoic metasediments of Godavari Proterozoic basin consist of Bhopal Patnam Granulite belt of 1.6 Ga. The southern part of the Godavari Proterozoic basin is in contact with the Dharwar craton that is characterized by Karimnagar granulite belt of 2.4-2.2 Ga at its contact (Santosh et al., 2004). However, the latter shows a thermal event of 1.6 Ga that has been reported from Karimnagar dykes in the vicinity of the granulite belt (Rao et al., 1990). c) This section is characterized by a central gravity low (L7, Fig 2b) and adjoining gravity highs along the shoulders that have been attributed to Gondwana sediments and high density intrusives, respectively (Mishra et al., 1999).

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d) A gravity profile (profile V, Fig 1b) and modeled crustal section is given in Fig 4a that shows a paired regional gravity anomaly of a regional high (H) over the Godavari Proterozoic and exposed Granulite rocks and regional low (L) over adjoining cratons due to crustal thickening. The crustal thickening might be related to under plating as density of this body (3.1 g/cm3) is higher compared to normal lower crust. The gravity high H is attributed to a high density intrusives in the upper crust (2.8 g/ cm3). Short wave length anomalies, A-F are related to shallow bodies of high and low densities that are not geodynamically significant. e) Gravity high over Proterozoic terrane caused by high density bodies in the upper crust and exposed granulite lower crustal rocks and gravity lows over Archean craton caused by crustal thickening and superimposed gravity highs and lows over it due to shallow high and low density intrusives, respectively suggest collision tectonics of Meso Proterozoic period between Bastar and Dharwar Craton that gave rise to this mobile belt with Bhopalpatnam granulite belt of this period. This convergence is approximately N-S direction that might be related to convergence along the SFB towards north of it as discussed above.

Figure 4a. Observed and computed Bouguer anomaly along profile V (Fig 1b) with the modelled crustal section. Regional field shows a high over Proterozoic metasediments and exposed granulite rocks and low over adjoining cratons that are modelled due to high density body (+0.19 g/cm3) in the upper crust and low density body (-.12 g/cm3) in upper mantle, indicating crustal thickening, respectively. Upper section shows the geology along the profile.

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f)

Airborne magnetic anomaly of large amplitude (∼ 550 nT, Fig 4b) at a height of about 9000 (∼ 2.7 km a.m.s.l) along Southern margin of the Proterozoic rocks (Karimnagar Granulite belt) also suggest mafic intrusive of high susceptibility 3.0x10-3 emu at a depth of about 5.3 km below m.s.l that may represent thrusted lower crustal granulite block. The remanant magnetization of this body, Inclination= -40o and declination= 300o required to match the observed and the computed field is typical of Meso Proterozoic rocks (Vindhyan sediment, Mishra, 1965) in this region indicating the period of collision and thrusting. It is also similar to those reported for dykes of the same period in this region (Rao et al., 1990).

Figure 4b. Airborne magnetic anomaly flown at 2.7 km a.m.s.l over southern part of Proterozoic Godavari basin suggesting a depth of 5.3 km below surface for a susceptibility of 3.0x10-3 emu and remanance magnetisation: Inclination= -40o, declination= 300o.

(iv) Peninsular Shield (L8-L12; H11-H12) and Connection to Madagascar g) The Southern Peninsular shield is primarily characterized by several gravity lows (L9-L12) with in a large wavelength gravity low (L8). The large wavelength

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gravity low (L8) has been primarily attributed to the thickening of the crust under S. Indian Shield and Western Ghats due to isostasy and low bulk density of crustal rocks (Arora et al., 2007). Small wavelength gravity lows can be attributed to shallow low density rocks such as granitic intrusions in this region (Tiwari et al., 2001; Krishna Brahmam and Kanungo, 1976). h) There is a significant gravity high, H11 (Fig 2b) between the western and the eastern Dharwar cratons which extends almost from the Transition zone between the Dharwar Cratons and the Southern Granulite Terrain (Bangalore) upto west coast of India under Deccan Volcanic province (Fig 1a &b). A gravity profile (Kavali-Udipi, Profile VI, Fig 1b) across Peninsular Shield from Fig 2b is given in Fig 5, that has been extended in Madagaskar based on Pilli et al. (1997) assuming juxtaposition of Madagascar along the west coast of India (Mishra and Prajapati, 2003). This profile shows three pairs of large wavelength gravity highs and lows referred to as XX’, YY’ and ZZ’ that are geodynamically significant. These highs and lows are modeled due to high density thrusted rocks T1, T2 and T3 while lows are primarily modeled due to crustal thickening, respectively constrained from seismic section along the same profile in India (Kaila et al., 1979). These sets of anomalies and bodies in Archean-Proterozoic terrane indicate collision tectonics. Some small wavelength anomalies are modeled due to shallow/exposed bodies. The crustal model related to XX’ pertains to Eastern Ghat Fold Belt (H15-H17) that represents a collision zone of Meso Proterozoic period as discussed in the next section. However, the other two sets of anomalies YY’ and ZZ’ pertains to the shear zone between the Eastern and the Western Dharwar Craton and western margin of Madagascar, respectively related to Meso-Neo Archean period. i) The WDC is characterized primarily by schist belts (Fig 1b) of Meso-Neo Archean period (Anil Kumar et al., 1996). They usually show large gravity lows such as L11 which are attributed to crustal thickening to a maximum of 42-44 km and low bulk density of crustal rocks due to granitic intrusions associated with schist belts (Arora et al., 2007). j) Various granitic batholiths of Neo Archean to Paleo-Proterozoic period of EDC (Jayananda et al., 2000) might have formed as subduction related magmatism between the western and the Eastern Dharwar cratons along the shear zone between them. However, the signatures of this shear zone on surface are not that prominent as in case of the SFB, ADFB or EGFB. Therefore, it may be considered as soft collision between the two that might have resulted from an oblique convergence (Chadwick et al., 2000). The schist belts of WDC and associated magmatism may represent back arc basins or marginal basins prior to it during Meso-Neo Archean period due to convergence of cratons of Madagascar and WDC.

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Figure 5. Observed gravity field and computed crustal model across Dharwar Craton (Profile VI, Fig. 1b) and its extension in Madagascar. The gravity field across Dharwar Craton and Madagascar are from Singh et al. (2002) and Pilli et al. (1997) respectively. It shows three sets of paired regional gravity anomalies; XX’, YY’ and ZZ’ attributed mainly to high density lower crustal rocks along the thrusts T1, T2 and T3 and crustal thickening. The short wave length anomalies L1, L2 and H1, H2, H3 are modelled due to shallow bodies. Densities of various layers and shallow bodies are given in figure as 2.70 g/cm3 etc which are adopted based on seismic velocities in Indian continent (Kaila et al., 1979; Reddy et al., 2000).

(v) Southern Granulite Terrain (SGT) (L13-L15; H13-H14) a) The terrain south of Dharwar Craton after Transition Zone is known as SGT (Chetty et al., 2006). It is largely occupied by lower crustal granulite rock and several deep seated intrusives of Neo-Archean-Paleo Proterozoic period. It is also characterized by several shear zones and thrusts such as Moyar-Bhavani Shear Zone (MBSZ), Palghat Cauvery Shear Zone (PCSZ), etc. These two major shear zones enclose the linear Cauvery Shear Zone (CSZ) also known as Palghat gap as it represents a geomorphological low land (Fig 1b). The terrane south of the CSZ is also characterized by Pan African event of Cambrian times. b) The most important gravity anomaly in this section are the linear highs over Transition zone and the CSZ (H13 and H14, Fig 2b) and adjoining lows L13 and L14 towards the south which are related to high density rocks in these sections and crustal thickening respectively (Mishra and Rao, 1993; Singh et al., 2003) that is also supported from seismic section (Reddy et al, 2003). The pairs of

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airborne magnetic anomaly associated with the MBSZ and PCSZ are attributed to trusted lower crustal rocks along these thrusts/shear zones which join to Mettur and Gangavalli shear zones, respectively towards the east forming arcuate shaped thrusts (Mishra and Vijaykumar, 2005). c) The high amplitude broad Bouguer anomalies (H13) north of transition zone from east to the west coast between the SGT and the Dharwar craton indicate thrusted high density lower crustal rocks along transition zone as there are no other known features of this orientation in this section which can give rise to this anomaly. A gravity profile across H13 and H14 from Palani to Kuppam (Profile VII, Singh et al., 2003) was extended north and westwards to cover the gravity high, H13 and gravity low, L14, respectively that is given in Fig. 6. It shows two sets of regional paired gravity anomalies, viz. H1, L1 and H3, L3 along with some short wave length high and low (A & B) related to shallow sources. This profile is modeled constrained from a seismic profile (Reddy et al., 2003). Gravity highs, H1 and H3 are modeled due to high density rocks (2.8 & 2.82 g/cm3) in the upper crust that may represent lower crustal rocks and gravity lows are caused by crustal thickening upto 47-48 km. These two signatures in conjunction, viz. high density lower crustal rocks and crustal thickening are indicative of Archean-Proterozoic collision zones that has given rise to various shear zones and deep seated intrusives of anorthosites, carbonatites, etc. In this case these anomalies and corresponding model suggest that transition zone (H13) and Cauvery shear zone (H14) and associated high grade rocks formed due to this collision.

Figure 6. The geotransect Kuppam-Palani (Profile VII, Fig 1b) and its extension upto about 13o30’N towards north and upto coast towards south. The crustal model from Kuppam-Palani (Singh et al., 2003) based on seismic constraints (Reddy et al., 2003) is extended to cover entire section based on observed and computed gravity fields for the entire section. It shows two sets of paired gravity anomalies H1, L1 and H3, L3 with highs (H1, H3) related to high density mafic bodies H1’ and H3’ along Transition Zone and Cauvery Shear Zone respectively and lows (L1, L3) are related to crustal thickening towards south of TZ and PCSZ (L1’, L3’). The gravity high A and B are modeled due to exposed lower crustal rocks with mafic/ultramafic intrusives (A’) and a low-density granite body (B), respectively.

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D.C. Mishra and M. Ravi Kumar d) Geomorphological gap of Palghat gap (CSZ; H14) might be a latter phenomenon due to subsidence along the preexisting margin faults of MBSZ and PCSZ during Miocene and subsequent to it (Mishra and Vijai Kumar, 2005). e) The large amplitude gravity low (L14) over Cardomam hills is part of the Western Ghats gravity lows L9 and L11 that are caused by crustal thickening along Western Ghats due to isostatic compensation (Mishra and Rao, 1993). f) The Pan African event reported from south of CSZ may be related to the formation of Rodinia super continent.

(vi) Eastern Ghat Fold Belts and Adjoining Proterozoic Basins (H15 - H17;

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L12 – L13) and Extension in Sri Lanka a) The Eastern Ghat Fold Belt (EGFB) of Meso Proterozoic period (1.4-1.0 Ga, Paul et al., 1990) is largely characterized by gravity highs along east coast of India (H16-H17) which extends from south of Bhubaneshwar up to Chennai and further south up to southern tip of India as H15 (Mishra et al., 2006). It extends even in the central part of Sri Lanka as gravity high (Fig 7a, Hatherton et al., 1975) related to Highland complex of Meso Proterozoic period almost same as EGFB. Highland complex consist of Kadugannawa complex that is characterized by mafic intrusives of about 1.0 Ga (Brown and Kriegsman, 2003). This map is corrected for the geoid low in the Indian ocean (Marsh, 1979) to remove the negative bias due to deep seated sources from the mantle. Inset of Fig 7b shows the spectrum of this Bouguer anomaly map that suggest three layers at depths of 34, 9 and 4.7 km representing Moho, upper crustal and basement sources. An EW gravity profile across this gravity high (Fig 7b) suggest high density intrusive similar to that modeled for EGFB with crustal thickening towards the east from about 35 km upto 40-41 km. An average crustal thickness of 35 km based on Bouguer anomaly is also inferred by Tantrigoda and Geekiyanage (2008). b) The gravity high due to the EGFB (X, Fig 5) is related to west verging thrusted block of high density rocks (T1). The adjoining low (X’) west of it (L12, Fig 2b) is related to crustal thickening under eastern part of the Proterozoic Cuddapah basin that represent a foreland basin to EGFB orogenic belt. The thrusted block and adjoining crustal thickening suggest collision of Indian Peninsular Shield presumably with Antarctica during Meso-Proterozoic period as suggested from the similarity of rocks in two sections. Similarly, L13 related to contact of Bastar craton with EGFB may also represent crustal thickening as in the case of L12.

5. LITHOSPHERE UNDER INDIAN CONTINENT Lithospheric sources are defined by large wavelength gravity anomalies. It is, therefore, essential to know the spectral characteristics of the Bouguer anomaly map of India and obtain large wavelength component from it.

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Figure 7a. Geoid corrected Bouguer anomaly map of Sri Lanka with geological boundaries superimposed on it. XX’ is Profile along which gravity anomaly is modelled as given in Fig. 7b. Spectrum vs wave number of Geoid corrected Bouguer anomaly is given in the inset, which shows three linear segments of slopes corresponding to 34, 9 and 4.7 km which may represent depth to Moho and sources in the upper crust.

5.1. Spectrum of Bouguer Anomaly Map of India As discussed above, Bouguer anomaly map of India (Figs 2a and b) shows linear gravity highs due to fold belts and lows due to sedimentary basins. However, there are some large wavelength anomalies as gravity low L8 over S. Indian Peninsular Shield whose sources are deep seated. To investigate these deep seated sources, spectral analysis of this map was undertaken (Section 2.0). Spectrum of Bouguer anomaly map of India (Fig 2a and b) and its northern (20oN upwards, Fig 2a) and southern parts (20oN downwards, Fig 2b) are computed and given in Fig 8a, b and c that suggest long wavelength sources in the upper mantle at depth of 160-180 km that represents lithosphere-asthenosphere boundary (LAB) based on results of

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seismic tomography as described above. The other sources are located at average depths of 36-55 km, 22-26 km and 6-9 km representing Moho, lower crust and shallow basement sources. As described above, the depth to Moho varies considerably from Western Dharwar craton (55 km) to the Eastern Dharwar craton (31 km) (Kieselev et al., 2008). Deep seismic sounding have also suggested crustal thickness varying from about 55-34 km under Indian Peninsular Shield (Prasad, 2008). Depths estimated from three spectrums of data drawn from the large data set being within error limits (10-15%) suggest the stability of the computed spectrum and reliability of the results inferred from them (Blackman and Tukey, 1958).

Figure 7b. Crustal model along Profile XX’ (Fig. 7a) computed using three layered standard crustal model with densities given in kg/m3. L1 and L2 are flanking lows with a central gravity high (H1). It shows crustal thickening (40-41 km) towards east with high density intrusive related to second layer in the upper crust.

5.2. Low Pass Filtered Regional Map and Modelling along Profiles The low pass filtered Bouguer anomaly for the first and second segment related to wave number (.012) and wavelength >523 km (Fig 9) shows large amplitude gravity lows, L1 and L2 over the Himalayas and South Indian Shield, respectively indicating the dominance of low density rocks in lithospheric mantle under these sections while NW and SE sections show gravity highs (H1 and H2). Tomography images also shows high velocity only in the central part of India upto a maximum depth of 200 km starting from Himalayas to the S. India while NW and SE part shows normal or lower velocity sections (Lebedev and Van der Hilst, 2008). It is well known that Keruguelen hot spot affected the break up of India from Antarctica at about 118-120 Ma and Mahanadi basin along east coast of India that coincides with the center of gravity high H1 and Lambert rift of Antarctica were conjugate structures. Kerguelen plume might have been centered at this junction of Mahanadi and Lambort rift causing lithospheric upwarp or thinning of the lithosphere and intrusives in this section (Mishra et al., 1999).

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Figure 8a. Spectrum of the Bouguer anomaly map of India showing linear segments with depths of 178, 48, 26 and 9 km.

Figure 8b. Spectrum of the northern part of the Bouguer anomaly of India showing linear segments of depths 163, 36, 16, 8 and 2 km. Figure 8. Continued on next page.

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Figure 8c. Spectrum of the southern part of the Bouguer anomaly map of India showing linear segments with depths 183, 55, 22 and 6 km.

Raval (1989) suggested that NW India is affected by Reunion plume while Kennett and Widiyantoro (1999) had suggested low velocity in upper mantle under NW India that is affected by Reunion plume that gave rise to Deccan trap during late Cretaceous. The gravity high, H2 in NW India centered at Saurashtra and offshore, in fact may represent the signatures of the break up of Africa from the Indian plate in the form of lithospheric upwarp or high density rocks as this break up was initiated from offshore Saurashtra on the Indian side and Somali basin on the African side. Further, there are several Jurassic basins in NW India that might have been produced due to these intrusives. The gravity highs, H3 and H4 in the northern part is caused by flexures of the Indian lithosphere under load of Himalayas towards the north and the west as has been suggested in case of oceanic subduction zones known as outer rise (Turcotte et al., 1978). The gravity high, H4 extending from Delhi westwards appears to represent the part of crustal bulge whose shallow manifestation occurs in the form of Delhi-Lahore-Sargodha ridge (Duroy, 1989). Two profiles (i) N-S along 77oE and (ii) E-W along 12.5oN passing through minimum value of the gravity low over S. Indian Shield in the low pass filtered map for wavelength >523 km (Fig 9) are modeled at average depth obtained from the spectrum. Fig 10a is the N-S profile along 77oE that is modeled for a density of 3250 kg/m3 while surrounding rocks are of density 3300 kg/m3. It shows a maximum lithospheric thickness of 179-180 km that reduces to 140 km under the lithospheric upwarp of Ganga basin further increasing northwards to 200 km under Ganga basin. Based on seismic tomography, Priestley et al. (2008) have shown a high velocity zone upto 150-160 km under NW India increasing to about 200 km under northern part of Ganga basin. Their velocity profile also shows a bulge under Ganga basin that might be synonymous with the lithospheric upwarp upto 140 km shown in the gravity

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model (Fig 10b). The second profile along 12.5oN is modeled in Fig 10b that also shows a maximum lithospheric thickness of 179 km reducing to 160 km in the eastern part for a low density body of 3250 kg/m3.

Figure 9. Low pass filtered Bouguer anomaly map for first and second segments of spectrum (12a) corresponding to wave number .012 and wavelength >523 km related to sources in the lithospheric mantle.

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Figure 10a. A N-S profile along 77oE of low pass filtered map (Fig 9) and model of lithospheric mantle showing low density rocks of 3.25 g/cm3.

Figure 10b. An E-W profile along 12.5oN of the low pass filtered map (Fig 9) and model of lithospheric mantle for low density rocks of 3.25 g/cm3

6. CHAMP-SATELLITE MAGNETIC MAP OVER INDIA AND TIBET Fig 11 is the CHAMP satellite magnetic map observed at 400 km and continued downwards at 50 km obtained from the Website: http://geomag.colorado.edu/lithomod.html. Most of the major magnetic anomalies of this map are correlated to surface geology and tectonics of Indian continent and Himalayan-Tibetan terrane which was also true in case of

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earlier MAGSAT anomalies (Mishra and Venkatarayudu, 1985) with some differences mainly in the amplitude of these anomalies.

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Figure 11. CHAMP satellite magnetic data observed at 400 km continued downwards to 50 km. H1-H7 and L1-L7 represent magnetic highs and lows related to different tectonic units and their gradients mostly coinciding with faults/thrusts.

Some of the major magnetic anomalies of this map (Fig 11) are as follows. i.

ii.

iii.

iv.

It shows sets of magnetic highs and lows, H1, L1 over Tarim basin and Quaidam basin of Tibet separated by a large gradient coinciding with the Altyn Tagh and Kunlun faults. The magnetic high H1 is attributed to Permian mafic dykes of Tarim basin which are prevalent through out the basin. Similarly Lhasa block of Tibet and Himalayas (Fig 11) are characterized by magnetic highs and lows, H2 and L2 separated by a sharp gradient related to oceanic crustal rocks (ophiolites) along Indus-Tsangpo suture zone. The gradient between magnetic highs and lows, H4 and L2 coincides partially with the Himalayan Frontal Thrusts such as Main Boundary Thrust (MBT), Main Central Thrust (MCT) etc. which are occupied by mafic rocks. Magnetic low, L3 and high, H3 coincide with the Aravalli-Delhi and Satpura Fold Belts, respectively which represent Proterozoic collision zones as discussed above consisting of mafic rocks including ophiolites and granulites of MesoProterozoic Period. The magnetic anomaly L3 and H3 extends to the NW and

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v.

vi.

vii.

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viii.

ix.

Eastern Himalayas and so are these features which are represented by these anomalies. The magnetic highs, H3 in its southern part coincides with alkaline complexes as volcanic plugs of Deccan trap eruption in Saurashtra which appears to extend from Arabian sea to continent in NW India (Western Rajasthan) where it bifurcates to Western Himalaya and NW Himalaya. The former representing Delhi-Lahore-Sargodha basement ridge in this section. Its gradient with the magnetic low, L3 coincides with the contact (Proterozoic suture) between western Rajasthan block and Aravalli-Delhi Fold Belt (ADFB) towards the east. The part of magnetic high, H3 in Saurashtra and Rajasthan can also be attributed to the breakup of Africa from India and related intrusives during Jurassic period that gave rise to several contemporary basins in this region. Magnetic low, L4 coincides with parts of Deccan volcanic Province South of Satpura Fold Belt (SFB) and its gradient with magnetic high, H4 coincides with the suture related to Meso Proterozoic collision zone between Bundelkhand and Bhandara cratons towards north and south respectively, inferred from gravity studies (Mishra, 2006). This suture extends almost from west coast of India to Shillong plateau and Eastern Himalayas consisting some well known faults and shear zones such as Tapti fault, Central Indian Shear, Singhbhum thrust, etc. The magnetic high, H5 extending from the west to the east coast with NE-SW trend coincides with Dharwar folding. It’s southern margin coincides with the transition zone between the Dharwar craton towards north and southern granulite terrane towards south. Magnetic low, L5 and High, H6 coincides with the Cauvery Shear Zone and exposed Khondalite lower crust rocks, respectively which have provided similar nature of airborne magnetic anomalies caused by mafic intrusives in the CSZ. These mafic intrusives being similar to oceanic crustal rocks in certain section suggest it to be a Proterozoic collision zone. Arabian Sea and Bay of Bengal provide some significant magnetic anomalies, H7, L7 and L6 and H6, respectively. The former set (H7 and L7) are caused by continental shelf and transitional crust occupied by igneous intrusives from Reunion plume which gave rise to Deccan trap eruption. The latter (L6 and H6) in Bay of Bengal showing a NE-SW trend appears to represent sea mounts and intrusives related to 85 and 90 East Ridge. Magnetic anomalies with E-W and NE-SW trends in Bay of Bengal and along east coast of India may represent basement anomalies due to changes in the thickness of sediment forming Bengal fan.

6.1. Spectral Analysis of CHAMP Satellite Magnetic Data This map shows some major magnetic anomalies of large and small wave lengths, suitable for spectral analysis and wavelength filtering. Spectral analysis of observed magnetic field provide depth estimates, to the causative sources at different levels based on slope of the spectral decay as described above for gravity field. The application of spectral decay to estimate the depth to the magnetic sources at different levels in the same manner as for

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gravity field has been suggested by Naidu (1970), Specter and Grant (1971) and Hahn, Kind and Mishra (1976). Bilim (2007) has used spectral slope of airborne magnetic field to define Curie point geotherm under western Anatolia that is validated from geothermal gradients and observed gravity field. Therefore the digital data of this map is transformed in the frequency domain using GEOSOFT and its power spectrum versus wave number is given in Fig 12a that provides two straight line segments with slopes equivalent to 154 km below the surface and shallow sources at the surface after subtracting 50 km, height of the downward continued CHAMP satellite data. In order to test the validity of the spectrum it is divided into two blocks, upper (northern) and lower (southern) from 25oN consisting of Himalayas and Tibet and Indian Shield and adjoining oceans, respectively and their spectrum versus wave number plots are given in Figs 12b and 12c. These plots provided linear segments with slopes equivalent to 159 and 148 km below surface and shallow sources close to surface (0-9 km). In this case also the depth estimated from the spectrum of different data set drawn from the large data matrix being within the error limits suggest the stability of the computed spectrum and reliability of the estimates made from them (Blackman and Tukey, 1958).

Figure 12. Spectrum versus wave number plots with their slopes equal to the depth to the causative sources. (a) Total data set digitized at 7.2 km interval

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Figure 12. Spectrum versus wave number plots with their slopes equal to the depth to the causative sources. (b) Northern part north of 25oN consisting mainly of Himalayan and Tibetan Terranes

Figure 12. (c) Southern part south of 250 N representing Indian Shield and adjoining Arabian Sea and Bay of Bengal

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The first spectral segment related to sources at depth of about 150-160 km appears to be quite reliable as it is present in all three spectrums computed for different data set drawn from the main data source providing almost same depths within the limits of lithospheric thickness suggested from seismic studies. Its credence is also supported from the fact that no other linear segment is obtained randomly, in any of these spectrums between shallow sources up to basement and the deeper sources provided by the first segment of these spectrums. However, magnetic anomalies originating from upper mantle at this depth is quite intriguing as Curie point geotherm, a temperature beyond which magnetization cannot exist, is mainly confined in the crust. It, there fore appears that magnetic signals represented by the first segment of the spectrum do not represent the conventional magnetic signals originating from the crustal sources. In order to find out the cause of magnetic sources in the upper mantle we examined the kind of rock types occurring in the upper mantle in this section. As described above, tomography experiments suggested high velocity lithosphere under Indian continent which represented the cold subducted Indian/Tethyan lithosphere after collision of Indian and Asian plate. Mahatsente and Ranalli (2004) have shown by numerical modeling that subducted lithosphere maintains a temperature of 300-400oC in the upper mantle upto a depth of 150200 km even after 30 Ma that is below the Curie point of magnetite (575oC) and would produce large wavelength magnetic anomalies. It is similar to Wadati-Benioff Zone in subducting plates where deep focus earthquakes occur due to brittle natures of rocks. The depth of magnetically active rocks in the upper mantle (150-160 km) coincides with the low density and high velocity rocks representing cold subducted Indian/Tethyan lithosphere under Indian continent.

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7. DISCUSSION AND CONCLUSION 7.1. Archean-Proterozoic Cratons and Fold Belts Cratons of the Indian continent are surrounded by fold belts also known as mobile belt that primarily represents Meso-Neo-Proterozoic collision zones. Fig 1a shows the major cratons of the Indian Shield and convergence directions that operated during that period as per the study presented above. Towards the north the present day convergence of Indian plate across Himalayan Fold Belt is shown from SW to NE direction. South of it, the Bundelkhand craton in the center converged in a NE-SW direction during Meso-Neo Proterozoic period to collide with the basement rocks of the Western Rajasthan (Marwar Block) to wards the west to form ADFB and towards the south with the Dharwar-Bhandara-Singhbhum cratons to form SFB with Central Indian Suture (CIS) in the central part. The SFB and CIS even extended westwards upto the coast and eastwards to Shillong Plateau and Eastern Himalaya to form an intra continental collision zone. This collision gave rise to island arc type of magnetism and back arc basins west of ADFB in Marwar block and south of SFB in Bhandara and Singhbhum cratons (Table 1). Dharwar, Bhandara and Singhbhum cratons separated by Gondwana rift basins might have been parts of a large craton before the formation of these rift basins. Prior to this collision there was a rifting phase both along the eastern margin of the ADFB and northern margin of the SFB that gave rise to Paleo Proterozoic rocks along rifted

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margins, viz. Aravalli and Mahakoshal Group of rocks, respectively (Table 1). Mahakoshal Group of rocks in central part of the SFB are confined along Narmada Son Lineament (Fig 1b). Vindhyan sediments were deposited after this rifting phase over the platform of Bundelkhand craton that was folded and disturbed at the contact of the ADFB and the SFB during convergence phase and remained undisturbed away from them (Mishra and Rajasekhar, 2008). The occurrence of Mezo-Proterozoic metasediments on either side of Godavari basin suggest that it might have been a plane of weakness even during that period when the two blocks on either side of Godavari basin rifted to form Dharwar and BastarBhandara cratons. The Proterozoic metasediments were deposited on this rifted platform and subsequently converged under the influence of overall compressive regime in northern India from the north to the south as in case of the SFB. This collision gave rise Godavari Proterozoic mobile belt and related granulite rocks and other intrusives. In southern part, the Dharwar craton was separated in two parts Western and Eastern Dharwar cratons, Western being characterized by schist belts of Meso-Neo Archean period while EDC is composed of Archean gneisses with several granitic intrusions of Neo- Archean times. South of Dharwar craton is the Southern Granulite Terrain with exposed granulite rocks of Neo Archean-Paleo Proterozoic period and several deep seated intrusives of anorthosite and carbonatites. The model presented above suggests that the Western and the Eastern Dharwar cratons collided west to east giving rise to subduction related linear granitic intrusions of EDC. This was in fact an oblique soft collision in NW-SE direction that did not give rise to large scale thrusting along the contact between the two (Fig 1a) . Almost at the same time, the two together collided with the Southern Granulite Terrain along Transition zone that gave rise to granulite rocks and shear zones like MBSZ, PCSZ, CSZ, etc. With this the formation of Indian continent was completed that collided with Antarctica during Meso Proterozoic period giving rise to Eastern Ghat Fold Belt that extends along the entire east coast of India and even in Sri Lanka as Highland complex. It is interesting to note that the present day convergence in Himalayas (SW-NE, Fig 1a) is in general opposite to the convergence direction during Mezo-Proterozoic period in India. Paleomagnetic measurements (Mishra, 1965) also suggest southward movement of India during Proterozoic period to form Gondwanaland in the southern hemisphere. In case the movement of plates are related to convection cells in the asthenosphere, in that case it appears that pattern or direction of convection cells changes over this period of time (∼ 1.0 billion years) at least in this particular case related to the Indian plate. It is, however, difficult to explain that how fold belts of Proterozoic period are still maintained as high lands. An approximate balance between mountain and root mass suggests that the continental lithosphere remains weak enough to permit exhumation of crustal roots in fold belts in response to surface erosion for hundreds of million of years. The amount of such uplift, however, appears to be significantly reduced by progressive loss of root buoyancy due to metamorphic reactions (Fischer, 2002). However, the loss of root buoyancy alone cannot explain the occurrences of Proterozoic Fold Belts as high lands even after erosion for hundreds of million years. There must be some mechanism for crustal thickening as uplift and exhumation take place over the geological period that may be opposite of delamination in case of thickened crust implying additions in the crust through mantle rocks as crust thins out. As fold belts are initially under compensated as discussed above in case of Himalayas with time become parts of the craton along their margins, principles of isostasy applies to the craton as a whole instead of fold belts separately and therefore, erosion based uplift and crustal thinning is much less in case of fold belts compared

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to otherwise individual units. It is, however, well known that isostasy operates on regional scales of hundreds of kilometers of area.

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7.2. Lithosphere under Indian Continent and its Rapid Drift Spectral analysis and wave band filtering of Bouguer anomaly and modeling along profiles provide average thickness of lithosphere as 160-180 km. It also suggests predominance of low density rocks in the lithospheric mantle that provides high velocity in seismic tomography results as discussed above. The low density and high velocity rocks in lithospheric mantle suggest that it is part of cold subducted Indian lithosphere that is further confirmed from CHAMP satellite magnetic data giving rise to magnetic anomalies from a depth of 150-160 km as its temperature is lower compared to Curie point geotherm. However, NW and SE sections along coastal margins of Indian continent show high density rocks in the lithospheric mantle that is supported from normal velocity or slightly low velocity in seismic tomography. These high density and low velocity sections can be attributed to the lithospheric upwarp or high density intrusives caused by the plumes during break up of India from Gondwanaland. The eastern coast is presumably affected by Kerguelen hot sport during break up of India from Antarctica at about 118-120 Ma while west coast in the northern part off Saurashtra and Kutch is affected by several plumes such as at the time of break up of Africa from India and subsequently Reunion plume that gave rise to Deccan trap rocks on the western part of Indian continent. These low density and high velocity rocks of lithospheric mantle provide buoyancy to the Indian continent that drives the Indian plate with a relatively higher speed as discussed above. Tomography experiments (Li et al., 2006 and Lebedev and Van der Hilst, 2008, Priestley et al., 2008) ) have suggested high velocity rocks under Indian continent extending almost from Moho to about 160-200 km depth that defines the lithosphere under cratons underlain by low velocity rocks of asthenosphere. However, high velocity zone further appears at a depth of about 600 km below the transition zone extending into lower mantle. In this light, the large wavelength gravity low observed over Indian Peninsular Shield (H8, Fig 2) and Indian ocean (Mishra et al., 2004) and geoid low observed over southern Indian Shield and Indian ocean (Sandwell and Smith, 1997) can be attributed to low density rocks in the lithospheric mantle and asthenosphere. As general elevation of Indian Shield (Karnataka-Deccan Plateau) is only 700-800 m, this large amount of low density rocks in upper mantle would cause over compensation making the whole region buoyant. It is well known that the movement of Indian plate at a speed of about 4.8 cm/year (Royer and Patriat, 2002) is one of the fastest moving plate that can be attributed to this buoyancy caused by low density rocks in the upper mantle. Previously, it has been attributed to several causes as discussed above. In fact the fast movement of Indian plate might be due to combination of more than one factor including buoyancy due to low density rocks in the lithospheric mantle and asthenosphere as discussed above. In fact, large wave length gravity low and geoid low of S. Indian Shield is centered south of India in the Indian ocean around Sri Lanka (Mishra et al., 2004) that makes the southern part of the Indian plate more buoyant compared to the northern part that would produce a regional tilting of the Indian free-board from the south to the north downwards. This is seen even in thickening of lithosphere from the south (160-180 km) to the north (200220 km) and relatively rugged topography of the S. Indian Shield vis-à-vis Archean-

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Proterozoic period of their formation. This tilting would also cause faster under thrusting of the Indian plate along the Himalayan thrusts and accordingly the faster drift of the Indian plate. The uplift of the southern part of the Indian plate is further accentuated due to load of Himalayas and Tibet at its northern margin as in case of a loaded beam. The NW-SE structural and geomorphological trends of the S. Indian Shield that are mainly confined to the large wavelength gravity lows, L8 (Fig 2b) and L2 (Fig. 9) are perpendicular to the plate motion (NE-SW) which also indicate the role of buoyant lithosphere caused by subducted Tethyan/Indian lithosphere in the uplift. North of this gravity low, the structural trends changes to ENE-WSW to NE-SW (H6-H8 and H3, Fig 2a) that may represent their original trends. This kind of uplift in recent times of the southern Indian Shield might be responsible for larger numbers of SCR earthquakes in this region compared to any other stable continental regions (Kayal, 2008). In addition, receiver function analysis (Kieselev et al., 2008) suggests the absence of high velocity keel under the Indian Shield (cratons) that is present under most of the cratons world over which provides further buoyancy. The keel might have been delaminated due to large movement of the Indian plate since Proterozoic period that was supposed to be located in northern hemisphere (34oN) at that time and drifted from there to the southern hemisphere (60oS) to form Radina and Gondwanaland and again back to northern hemisphere after their break up (Mishra, 1965).

ACKNOWLEDGEMENT Authors are thankful to Director, NGRI for permission to publish this work and to CSIR for Emeritus Scientist Scheme.

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REFERENCES Acharyya, S.K. (2003b). A plate tectonic model for Proterozoic crustal evolution of Central Indian Teconic Zone. Gond. Geol. Magz., 7, 9-31. Anil Kumar, Bhaskar Rao, Y.J., Sivaraman, T.V. and Gopalan, K. (1996). Sm-Nd ages of Archean meta-volcanics of the Dharwar craton, South India. Precambrian Res., 80, 205216. Arora, K., Rajasekhar, R.P., Mishra, D.C. (2007). Density models of crust under Dharwargranite greenstone terrain and the Satpura mobile belt: Archean-Proterozoic Analogue of plate tectonics. Mem. Gondwana Res., 10 (In Press). Banerjee, P. and Satya Prakash (2003). Crustal configuration in NW Himalaya from gravity measurements along Kiratpur-Leh-Panamik transect. J. Geol. Soc. of India, 61, 529-539 Bilim, F. (2007). Investigations into the tectonic lineaments and thermal structure of KutahyaDenizli region, western Anatolia, from using aeromagnetic, gravity and seismological data. Physics of the Earth and Planetary Interiors, 165, 135-146. Blackman, R.B. and Tukey, B.W. (1958). The measurement of power spectra, Dover Publications, New York, 1-190. Brown, I., Kriegsman, L.M. (2003). Proterozoic crustal evolution of southern most India and Sri Lanka. In: Yoshida, M., Windley, B.F., Dasgupta, S. (Eds.). Proterozoic East

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Geodynamics of Indian Free-Board: Archean-Proterozoic Collision Zones

269

Gondwana Super Continent Assembly and Break up. Geological Society, London, Special publication, .206, 169-202. Burke, K.C.A. and Dewey, J.F. (1973). An outline of Precambrian plate development, In: Tarling, D.H and Runcorn, S.K. (Eds.). Implications of Continental Drift to the Earth Sciences. Academic Press, London, 1035-1045. Chadwick, B., Vasudev, V.N. and Hedge, G.V. (2000). The Dharwar craton, Southern India, interpreted as the result of late Archean oblique convergence. Precambrian Res., 99, 91111. Chakrabarti, R., Basu, A.R. and Chakrabarti, H. (2007). Trace element and Nd-isotope evidence for sediment sources in the mid-Proterozoic Vindhyan basin, Central India. Precambrian Research, 159, 260-274. Chetty, T.R.K., Fitzsimons, IC.W., Brown, L.D., Dimri, V.P. and Santosh, M. (2006). Crustal structure and tectonic evolution of the southern granulite terrain, India. Gondwana Research, 10, 1-206. Choudhary, A.K., Gopalan, K. and Sastry, C.A. (1984). Present status of the geochronology of the Precambrian rocks of Rajasthan. Tectonophysics, 105, 131-140. Duroy, Y., Farah, A. and Lillie, R.J. (1989). Subsurface densities and lithospheric flexure of the Himalayan fore land in Pakistan, In: Malinconica Jr. L.L. and Lillie, R.J., (Eds.). Tectonics of the Western Himalayas, Geol. Soc. Am., Special Paper, 232, 203-216. Fedi, M., Quarta, T. and Santis, A.D. (1997). Inherent power law behavior of magnetic field power spectra from a Specter and Grant ensemble. Geophysics, 62, 1143-50. Fountain, D.M. and Salisbury, M.H. (1981). Exposed cross section through the continental crust: Implications for crustal structure, petrology and evolution. Earth Planet. Sci. Letts., .56, 263-277. Gibb, R.A. and Thomas, M.D. (1976). Gravity signature of fossil plate boundaries in the Canadian shield. Nature, 262, 199-200. Gokaran, S.G., Rao, C.K., Gupta, G., Singh, B.P. and Yamashita, M. (2001). Deep crustal structure in Central India using magnetotelluric studies. Geophys. J. Int., 144, 685-694. GSI-NGRI (2006). Gravity Map Series of India. Published by Geol. Survey of India, National Geophysical Research Institute, Hyderabad, India. Hatharton, T., Pattiaratchi, D.B. and Ranasinghe, V.V.C. (1975). Gravity map of Sri Lank, 1:1,000,000, Professional Paper, No.3. Geological Survey Department, Republic of Sri Lanka, 1-39. Hahn, A., Kind, E.G. and Mishra, D.C. (1976). Depth estimation of magnetic sources by means of Fourier amplitude spectra. Geophysical Prospecting, 24, 287-308. Jain, S.C., Yedekar, D.B. and Nair, K.K.K. (1991). Central Indian Shear zone : a major Precambrian crustal boundary. Jour. Geol. Soc. India. 37, 521-532. Jayananda, M., Moyan, J.F., Martin, H., Peucat, J.J., Auvray, B. and Mahabaleshwar, B. (2000). Late Archean (2550-2520 Ma) Juvenile magmatism in the eastern Dharwar Craton, Southern India: Constraints from geochronology, Nd-Sr isotopes and whole rock geochemistry. Precambrian Res., 99, 225-254. Kaila, K.L., Murthy, P.R.K., Mall, D.M., Dixit, M.M. and Sarkar, D. (1987). Deep seismic soundings along Hirapur-Mandla profile, Central India. Geophys. J. R Astr. Soc., 89, 399404. Kaila, K.L., Roy Chowdhury, K., Reddy, P.R., Krishna, V.G., Hari Narain, Subbotin, S.I., Sollogulb, V.B., Chekunov, A.V., Kharetcho, G.E., Lazarenko, MA. And Ilchenko, T.V.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Copyright © 2009. Nova Science Publishers, Incorporated. All rights reserved.

270

D.C. Mishra and M. Ravi Kumar

(1979). Crustal structure along the Kavali-Udipi profile in the Indian Peninsular Shield from deep seismic sounding. J. Geol. Soc. India, 20, 307-333. Kayal, J.R. (2008). Micro earthquake seismology and seismotectonics of South Asia, Capital Publishing Co., New Delhi, 1-503. Kennett, B.L.N., and Widiyantoro S. (1999). A low seismic wave speed anomaly beneath northwestern India: A seismic signature of the Deccan plume. Earth Planet. Sci Letts., 165, 145-155. Kieselev, S., Vinnik, L., Oreshin, S., Gupta, S., Rai, S.S., Singh, A., Kumar, M.R. and Mohan, G. (2008). Lithosphere of the Dharwar craton by joint inversion of P and S receiver functions. Geophys. J. Int., 173, 1106-1118. Krishna Brahmam, N., Kanungo, D.N. (1976). Inference of granitic batholiths by gravity studies in South India. J. of the Geol. Soc. of India, 17, 45-53. Kumar, P., Yuan, X., Kumar, M.R., Kind, R., Li, X. and Chadha, R.K. (2007). The rapid drift of the Indian tectonic plate, Nature, 449, doi:10.1038/nature06214, 894-897. Lebedev, S. and Van der Hilst, R.D. (2008). Global upper mantle tomography with the automated multimode inversion of surface and S-wave forms. Geophys. J. Int., 173, 505518. Li, C., Van der Hilst, R.D. and Toksoz (2006). Constraining P-wave velocity variations in the upper mantle beneath southeast Asia. Physics of the Earth and Planetary Interiors, 154, 180-195. Mahatsente, R. and Ranalli, G. (2004). Time evolution of negative buoyancy of an oceanic slab subducting with varying velocity. J. of Geodynamics, 38, 117-129. Marsh, J.G., 1979, Satellite derived gravity maps section 2. In: Lowman Jr. P.D. and Frey, H.V. (Eds.). A Geophysical Atlas for interpretation of Satellite Derived Gravity Data. NASA, Green Belt, Maryland, USA. McKenzie, D. and Priestley, K. (2008). The influence of lithospheric thickness variations on continental evolution. Lithos., 102, 1-11. Mishra, D.C., Singh, B. and Gupta, S.B. (2002). Gravity modeling across Satpura and Godavari Proterozoic Belts: Geophysical signatures of Proterozoic collision zones. Current Science, 83, 1025-1031. Mishra, D.C., Chandrasekhar, D.V., Venkata Raju, D.Ch and Vijai Kumar, V. (1999). Analysis of gravity and magnetic data over Lambert Glacier, Antarctica and its relation with Gondwana rift valleys of India. Earth and Planetary Science Letters, 172, 287-300. Mishra, D.C. (1965). Paleomagnetism of Vindhyan and Bijawar group of rocks, India. Ph.D. Thesis. Banras Hindu University, India. Mishra, D.C. and Venkatrayudu, M.(1985). MAGSAT scalar anomaly map of India and a part of Indian ocean-Magnetic crust and tectonic correlation. Geophysical Research Letters, 12, 781-784. Mishra D. C., Laxman, G. and Arora, K. (2004). large wave length gravity anomalies over the Indian continent: Indicator of lithospheric flexure and uplift and subsidence of Indian Peninsular Shield relat0ed to isostasy. Curr. Sci., 84, 224-230. Mishra, D.C. and Prajapati, S.K. (2003). A plausible model for evolution of schist belts and granite plutons of Dharwar craton, India and Madagascar during 3.0-2.5 Ga: Insight from gravity modelling constrained in part from seismic studies. Gondwana Res., 6, 501-511.

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Geodynamics of Indian Free-Board: Archean-Proterozoic Collision Zones

271

Mishra, D.C. and Rajasekhar, R.P. (2008). Gravity and magnetic signatures of Proterozoic rifted margins: Bundelkhand craton and Bijawar and Mahakoshal Group of Rocks and Vindhyan basin and their extension under Ganga basin. J. Geol. Soc. Ind. (In Press). Mishra, D.C. and Rao, M.B.S.V. (1993). Thickening of crust under the granulite province of S. India and associated tectonics based on gravity-magnetic studies. Mem. Geol. Soc. of India, 25, 203-219. Mishra, D.C. and Vijai Kumar, V. (2005). Evidence for Proterozoic collision from airborne magnetic and gravity studies in southern granulite terrain, India and signatures of recent tectonic activity in the Palghat gap. Gondwana Research, 8, 1-12. Mishra, D.C. (2006). Building blocks and crustal architecture of Indian Peninsular Shield cratons and fold belts and their interaction based on geophysical data integrated with geological information. J. Geol. Soc. India, 68, 1037-1057. Mishra, D.C., and Pedersen, L.B. (1982). Statistical analysis of potential fields from surface relief. Geoexploration, 19, 247-265. Mishra, D.C., Chandrasekhar, D.V., Raju, D.Ch.V. and Vijai Kumar, V. (1999). Crustal structure based on gravity-magnetic modelling constrained from seismic studies under Lambert rift, Antarctica, Godavari and Mahanadi rift, India and their inter relationships. Earth & Planet. Sci. Letts., 172, 287-300. Mishra, D.C., Ravi Kumar, M. and Laxman, G. (2008). Lithosphere under Himalayas, Tibet and India and its Rapid Drift: Satellite and Surface Gravity Studies Integrated with Seismic Investigations. Communicated to Tectonophysics. Mishra, D.C., Singh, B., Tiwari V.M., Gupta, S.B. and Rao, M.B.S.V. (2000). Two cases of continental collisions and related tectonics during the Proterozoic period in India-insights from gravity modelling constrained by seismic and magnetotelluric studies. Precambrian Res., 99, 149-169. Mishra, D.C., Singh, B., Tiwari V.M., Gupta, S.B. and Rao, M.B.S.V. (2000). Two cases of continental collisions and related tectonics during the Proterozoic period in India-insights from gravity modelling constrained by seismic and magnetotelluric studies. Precambrian Res., 99, 149-169. Mishra, D.C., Vijai Kumar, V. and Rajasekhar, R.P. (2006). Analysis of airborne magnetic and gravity anomalies of peninsular shield, India integrated with seismic and magnetotelluric results and gravity anomalies of Madagascar, Sri Lanka and East Antarctica. Gondwana Research, 10, 6-17. Naidi, P.S. (1970). Fourier transform of large scale aeromgnetic field using a modified version of Fast Fourier Trnasform. Pure and Applied Geophysics,81,17-25. Naidu, P.S. and Mathew, M.P. (1998). Analysis of geopotential fields: A digital signal processing approach. Advances in Exploration Geophysics, Elsevier Amsterdam, 1-289. Negi, J.G., Pandey, O.P. and Agarwal, P.K. (1987). Supermobility of hot Indian lithosphere, Tectonophysics, 135, 145-156. Paul, D.K., Barman, T., McNaughton, N.J., Flecther, I.R;., Potts, P.J., Ramakrishnan, M. and Augustine, P.F. (1990). Archean-Proterozoic evolution of Indian charnockites-isotopes and geochemical evidence from granulites of the Eastern Ghat Belt. Journal of Geology, 98, 253-263 Pilli, E., Ricard, Y., Landeux, J.M., Sheppard, S.M.F. (1997). Lithospheric shear zones and mantle crust connections. Tectonophysics, 280, 15-29.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

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D.C. Mishra and M. Ravi Kumar

Prasad, B.R., Vijaya Rao, V. and Reddy, P.R. (1999). Seismic and magnetotelluric studies over a crustal scale fault zone for imaging a metallogenic province of Aravalli Delhi Fold Belt region. Curr. Sci., 76, 1027-1031. Prasad, B.R. (2008). Deep seismic sounding studies in India, Mem. Geol. Soc. of India; Significant Milestones in the Growth of Geophysics during 50 years Period (1958-2008) (In Press). Priestley, K., Debayle, E., Mckenzie, D. and Pilidou, S. (2006). Upper mantle structure of eastern Asia from multimode surface wave form tomography. J. Geophys. Res., 111, 120. Priestley, K., Jackson, J. and McKenzie, D. (2008). Lithospheric structure and deep earthquakes beneath India, the Himalaya and southern Tibet. Geophys. J. Int., 172, 345362. Rajasekhar, R.P. and Mishra, D.C. (2007). Crustal structure of Bengal basin and Shillong plateau: Extension of Eastern Ghat and Satpura mobile belts to Himalayan fronts and seismotectonics. Gondwana Research (In Press). Raju, P.S.R. (1986). Geology and hydrocarbon prospects of Prahhita-Godavari graben. Journal of Assoc. of Exploration. Geophysics, 7, 131-146. Rao, J.M., Rao, G.V.S.P. and Patil, S.K. (1990). Geochemical and paleomagnetic studies on the middle Proterozoic Karimnagar mafic dyke swarm, India, In: Mafic dykes and Emplacement Mechanism. (Eds.) A.P. Parkaer, P.C., rock Wood and D.H. Tucker, A.A. Balkema, Rotterdam, Brookfield, 373-382. Rao, T.S. (1987). The Pakhal Basin; A perspective. In: Purana basins of pensinsular India; middle to late Proterozoic based on the proceedings of the seminar. Memoir- Geological Society of India. 6, 161-187. Raval, U. (1989). On hot sports, Meso-orogenic tectonics and possible thermal networking beneath the Indian continent. Proc. Indian Geophys. Union, 314-330. Raval, U. (1993). Fast movement of the Indian plate, buoyancy due to plume and warm asthenosphere, Proc. of the 29th Annual convention of IGU, Hyderabad. Reddy, P.R., Vijayarao. V., Prasad, B.R., Sain, K., Prasadrao, P. and Prakaskhare (2003). Crustal seismic studies along Kuppam-Palani transect in southern granulite terrain. Mem. Geol . Soc. India, 50, 79-106. Reddy, P.R., Chandrakala, K. and Sridhar, A.R. (2000). Crustal velocity structure ofl the Dharwar Craton, India. J. Geol. Soc. India, 55, 381-386. Royer, J.Y. and Patriat, P. (2002). L’Inde part a la derive In: Museum National D’Historie Naturalle (France), Allegre, C.J., Avonac, J.P. and DeWever, P. (Eds.) Himalaya-Tibet, Le choc des continents, Paris, CNRS editions et Museum national de’Historie naturalle, 25-31. Sain, K., Bruguier, N., Murthy, A.S.N. and Reddy, P.R. (2000). Shallow velocity structure along Hirapur-Mandla profile using travel time inversion of wide angle seismic data and its tectonic implications. Geophys. J. Int., 142, 505-515. Sandwell, D.T. and Smith, W.H.F. (1997). Marine gravity anomaly from Geosat and ERS-1 Satellite altimetry. J. Geoph. Res., 102, 10039-54. Santosh, M., Yokoyama, K. and Acharyya, S.K. (2004). Geochronology and Tectonic Evolution of Karimnagar and Bhopalpatnam Granulite Belts, Central India. Gondwana Research, 7, 501-518.

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Geodynamics of Indian Free-Board: Archean-Proterozoic Collision Zones

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Sarma,S.V.S., Nagrajan, N., Someshwar Rao, M., Hari Narayana, T., Virupakhsi, G., Murthy, D.N., Sarma, M.V.C., and Gupta, K.P.B. (1996). Magnetotelluric studies along Mungwani-Rajnandgon in Central India. Proc. II, Int. Seminar on Geophysics, AESG, Hyderabad, 206-207. Sarkar, S.N., Gopalan, K. and Trivadi, J.R. (1981). New data on the geochronology of the Precambrians of Bhandara-Drug, Central India. Indian Jour. Earth Sci., 8, 131-151. Singh, A.P., Mishra, D.C., Vijai Kumar, V. and Rao, M.B.S.V. (2003). Gravity-Magnetic signatures and crustal architecture along Kuppam-Palani geotransect, South India. Mem. Geol. Soc. India. 50, 139-163. Sinha-Roy, S. (1988). Proterozoic Wilson cycle in Rajasthan. Mem. Gol. Soc. India, 7, pp.95108. Specter, A. and Grant, F.S. (1970). Statistical models for interpreting aeromagnetic data, Geophysics. 35, 293-302. Tantrigoda, D.A., Geekiyanage, P. (2008). preliminary crustal thickness map of Sri Lanka. J. Geol. Soc. of India, 71, 551-556. Tarney, J. Dalzid, I.W.D. and DeWit, M.J. (1976). Marginal basin ‘Rocas Verdes’ complex from S. Chile: A model for Archean greenstone belt formation, In: Windely, B.F., The Early History of the Earth, John Wiley & Sons, London, 131-146. Tewari, H.C., Dixit, M.M., Madhav Rao, N. and Venkateswarlu, N. (1997). The Paleomeso Proterozoic Delhi Fold Belt in north western India, evidence from deep reflection profiling. Geophys. Jour. Int., 129, 657-668. Tiwari V.M., Vyaghreswara Rao M.B.S. and Mishra, D.C. (2001). Density inhomogeneities beneath Deccan Volcanic Province, India as derived from gravity data. J. Geodynamics, 31, 1-17. Turcotte, D. L., McAdoo, D. C., and Caldwell, J.G. (1978). An elastic-perfectly plastic analysis of the bending of the lithosphere at a trench. Tectonophysics, 47, 193-205. Windely, B.F. (1973). Crustal development in the Precambrian, Phil. Trans. R. Soc. Lond., A 273, 321-341. Yedekar, D.H., Jain, S.C., Nair, K.K.K. and Dutta, K.K. (1990). The central Indian collision suture. In: Precambrian of Central India. Geo!. Surv. India, Nagpur, Spec. Pub!., 28, 143.

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In: Geomorphology and Plate Tectonics Editors: D. M. Ferrari, A. R. Guiseppi

ISBN: 978-1-60741-003-4 © 2009 Nova Science Publishers, Inc.

Chapter 10

NATURE OF PERMIAN FAUNAS IN WESTERN NORTH AMERICA: A KEY TO THE UNDERSTANDING OF THE HISTORY OF ALLOCHTHONOUS TERRANES Calvin H. Stevens1 and Paul Belasky2 1

Department of Geology, San Jose State University, San Jose, California, U.S.A. 2 Department of Geology, Ohlone College, Fremont, California, U.S.A.

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ABSTRACT Probably the most outstanding examples of the validity of the concept of terrane mobility and final accretion to a cratonal margin are provided by those terranes, now attached to the western North American cratonal margin, bearing Permian fusulinid (foraminiferal) and colonial rugose coral faunas. These terranes, which extend from Mexico to Alaska, are remnants of several different Permian paleobiogeographic provinces originally formed in different parts of the Paleopacific Ocean, as indicated by their distinctive faunas. Along the western margin of the North American craton, the Permian fusulinid and colonial rugose coral faunas vary considerably, but there are some marked similarities. Beyond this margin, there are three sets of terranes bearing different faunas that were accreted to the craton after Permian time. The first series, located mostly immediately west of the craton and commonly referred to as the McCloud Belt, bears somewhat different faunas from those of cratonal North America. Although the distance between these terranes and North America during the Permian is still debated, the faunal differences are substantial enough to suggest at least a moderate amount of original separation. Farther west there are terranes and blocks in mélanges that bear typical Tethyan faunas, which probably originated many thousands of kilometers farther out in the Paleopacific Ocean. Beyond these terranes is still another dispersed terrane, referred to as the Wrangellia terrane, with faunas somewhat related to those of the McCloud Belt. Data from the fusulinid and colonial coral faunas, with consideration of the available paleomagnetic data, suggest that many of these terranes had complicated histories, including changes in positions relative to the North American craton during the Permian. In the Early Permian the major terranes of the McCloud Belt were mostly at somewhat different latitudes relative to cratonal North America than they are today and perhaps 2000-3000 km offshore. The Wrangellia terrane lay farther north, but it also was

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Calvin H. Stevens and Paul Belasky separated from the North American craton by a considerable distance. The eastern Tethyan faunas occupied shelves around islands in the tropics far removed from North America. During the Middle Permian the terranes of the McCloud Belt and the Wrangellia terrane migrated about 15º southward relative to cratonal North America, and all of the terranes, including the eastern Tethyan terranes, may have begun to converge on the North American craton. In post-Permian time all of these terranes were accreted to the craton and smeared out thousands of kilometers along strike-slip faults at its margin.

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INTRODUCTION Western North America has been considered to be composed of a craton extending to the westernmost areas underlain by Precambrian basement, the margin of which can be delineated at approximately the Sr87/Sr86 0.706 isotopic boundary (e.g., Kistler, 1978; Stevens et al., 1992), and a series of allochthonous terranes that have been accreted to that margin (Fig. 1). These terranes were defined primarily on the basis of their tectonostratigraphic histories that differ from those of adjacent terranes and cratonal North America. Faunal data, especially from Permian faunas, also have been considered in definition of some of these terranes. Several terranes, including the Eastern Klamath, Stikine, and Quesnellia terranes, and various other smaller tectono-stratigraphic assemblages, bear similar fusulinid faunas, most of which were described by Skinner and Wilde [1965, 1966]. For these terranes thus considered to have been closely associated in the Permian, Miller [1987] introduced the name McCloud Belt. Although the faunas of these rocks are broadly similar and coeval with those on cratonal North America, in detail they are quite different. Another terrane, not considered to belong to the McCloud Belt because of its different geologic history, is the Wrangellia terrane, which was amalgamated with the Alexander terrane in the Pennsylvanian [Gardner et al., 1988]. The Wrangellia part of this composite terrane in Alaska contains some faunal elements in common with the McCloud Belt. West of most of the terranes bearing the McCloud Belt faunas, but inboard of the Wrangellia-Alexander terrane, there are other terranes, including the large Cache Creek terrane in western Canada (Fig. 1) and blocks in mélanges, that bear faunas with affinities to those of Asia and the Mediterranean. These faunas, often referred to as Tethyan, bear virtually no resemblance to those of either the North American craton, the McCloud Belt, or the Wrangellia terrane. These rocks will be referred to here as eastern Tethyan terranes.

PREVIOUS WORK Permian faunas in western North America have elicited considerable interest ever since the introduction of the concept of allochthonous terranes [e.g., Jones et al., 1977], because faunas of this age are more widespread on the craton and in the allochthonous terranes than those of any other age, thus allowing comparisons. Ross [1967a] recognized that in the Early Permian three different fusulinid associations were present in western North America: (1) the Pseudoschwagerina association represented on the craton, (2) the Chalaroschwagerina

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Nature of Permian Faunas in Western North America

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association of the McCloud Belt, and (3) the Sphaeroschwagerina association from the Eurasian-Arctic realm. This latter association was a precursor to the younger Verbeekinid association in the Tethyan realm, which is well represented in the Cache Creek terrane.

Canadian Arctic Islands 7

Anchorage

Alexander terrane Cache Creek terrane Quesnellia terrane ^^ ^ ^ ^^ ^^^

Stikinia terrane

Ca na da

Alaska

Margin of cratonal North America

^ ^ ^ ^^ ^ ^^ ^ ^ ^^ ^ ^ ^ ^^ ^^^ ^^^ ^ ^^ ^^ ^ ^ ^^ ^^ ^ ^ ^^ ^ ^^^ ^ ^^ ^^^ ^ ^^ ^ ^^ ^^

6

Wrangellia terrane

Canada USA

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Seattle

N Eastern Klamath terrane

1000 km

3

San Jose

5

4

2 1

Mexi

co

Figure 1. Location of major terranes considered here, location of cratonal faunas represented in this study, and approximate western edge of the North American craton based on the maps of Howell et al. [1985], Kistler [1978], and Stevens et al. [1992]. (1)=Texas; (2)=Arizona-New Mexico; (3)=Nevada; (4)=Bird Spring Shelf, California; (5)= Conglomerate Mesa, California; (6)=Western Canada; (7)= Canadian Arctic Islands. Note: only the mainland Alaskan outcrops of the Wrangellia terrane are shown because all faunal elements noted here are from that part of that terrane.

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278

Calvin H. Stevens and Paul Belasky

Later studies of Permian colonial rugose corals [e.g., Stevens and Rycerski, 1983] showed that the faunas of cratonal North America also differ significantly from those of the McCloud Belt. At that time no colonial rugose corals had been described from the eastern Tethyan rocks in North America, but those in the Tethys were known to be almost totally different from those on cratonal North America and in the McCloud Belt [e.g., Minato and Kato, 1965]. Thus, colonial rugose corals were shown to be at least as important as fusulinids for differentiation between the three faunal assemblages recognized by Ross [1967a]. More recently the paleobiogeographic significance of several groups of Permian fossils have been more thoroughly analyzed. These groups include not only fusulinids and colonial rugose corals, but also gastropods and brachiopods [e.g., Stevens, et al., 1990; Belasky et al., 2002; Belasky and Stevens, 2006]. These authors made statistical comparisons of the faunas between cratonal North America, the McCloud Belt, and the Tethys. To account for the differences between the compositions of the three major assemblages recognized by Ross [1967a] in western North America, terrane transport over long distances in the Paleopacific Ocean has been suggested by various writers [e.g., Ross and Ross, 1983; Stevens and Rycerski, 1983; Belasky and Runnegar, 1994; Belasky and Stevens, 2006]. Newton [1988], in contrast, suggested that it was just as likely that many of the organisms in the terranes, including those of Tethyan affinity, were dispersed (e.g., as larvae) long distances across the Paleopacific Ocean and therefore do not require the allochthonous terranes to have traveled long distances. Newton’s hypothesis points to a weakness in assessing the original positions of terranes based on faunal relationships alone, especially if the ages are not identical. Thus, if Newton [1988] is correct, the presence of Tethyan fossils in North America may simply reflect an expansion of the Tethyan paleobiogeographic province, especially in the Late Permian, perhaps due to changes in current patterns or temperature regimes. Paleomagnetic work has aided greatly in the understanding of relationships between some terranes and the North American craton. Scotese and McKerrow [1994], Scotese and Langford [1995], and Ziegler et al. [1996] employed paleomagnetic data to show the latitudinal position of North America for different Permian epochs. According to their maps, the paleoequator intersected the west coast of the North American craton in west Texas, and the Canadian Arctic Islands were at latitudes of 35-40˚N during the Early Permian. By the Middle Permian, northward movement of North America placed these areas at 2˚-3˚ higher latitudes than they had been in the Early Permian. Paleolatitudes are also relatively well established for some of the allochthonous terranes. Available data suggest that in the Early Permian the central part of the Alexander terrane was at 25˚-30˚N [Butler et al., 1997] and the central part of the Stikine terrane was at about 23˚±6˚N [Irving and Monger, 1987]. During the Middle to Late Permian, the Eastern Klamath terrane lay at 18.1˚ ±7.0˚N [Mankinen et al., 1989] or, based on a recalculation of all data, at 0˚±10˚ relative to their present position in northern California, which was at about 18˚N at that time [Mankinen and Irwin, 1990]. On the basis of the paleomagnetic data and statistical tests, including conventional and probabilistic indices of similarity of Permian faunas, as well as multivariate analyses and faunal diversity, the Eastern Klamath, Stikine, and Quesnellia terranes, which compose the major parts of the McCloud Belt, were interpreted by Belasky et al. [2002] to have been at about the same latitude during the Early Permian as those parts of the North American craton that are the closest to those terranes today. The diversity of the faunas in the Wrangellia

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Nature of Permian Faunas in Western North America

279

terrane in mainland Alaska (part of the amalgamated Wrangellia-Alexander terrane, Fig. 1), however, was lower than expected when a paleolatitude of 25˚N for the Wrangellia terrane was utilized. Belasky et al. [2002] suggested that this was due to cool water currents bathing the shores of this terrane. It is now apparent, however, that the Wrangellia terrane in Alaska was almost certainly at a higher latitude than 25˚N in the Early Permian based on paleomagnetic data from the amalgamated Alexander terrane ( 25˚-30˚N [Butler et al., 1997]), which lies south of that part of the Wrangellia. Thus, the paleomagnetic data from the Alexander terrane place the Wrangellia terrane in mainland Alaska at about the latitude of southern Yukon Territory (Fig. 2), which was at about 32˚ in the Early Permian. Because paleolongitudes cannot be ascertained from paleomagnetic data, interpretation of longitudinal placements of terranes is much more subjective. However, interpretations of the original longitudinal separation of the three major sets of terranes during the Early Permian have been made based on various statistical comparisons of their contained faunas. Stevens et al. [1990] suggested that during the Early Permian the Eastern Klamath terrane was located at least 5000 km offshore from cratonal North America based on Otsuka similarity coefficients between coral faunas of the Eastern Klamath terrane and cratonal North America. This distance was derived from a comparison of similarity coefficients between those of modern coral faunas at different distances between shallow-water shelves in the Pacific Ocean with those of the Permian faunas in question. Later, on the basis of trend-surface analysis, Belasky and Runnegar [1994] suggested that the Eastern Klamath and Stikine terranes of the McCloud Belt were close to one another and up to 6700 km west of North America during the Early Permian with the Wrangellia terrane being somewhat closer to the craton. Distances between those three terranes and cratonal North America during the Early Permian were later revised downward to 2000-3000 km [Belasky et al., 2002; Belasky and Stevens, 2006] on the basis of additional statistical analyses of three faunal groups (fusulinids, colonial corals, and brachiopods). Trend-surface analysis, probabilistic estimates of taxonomic diversity, and similarity applied to modern Indo-Pacific coral genera also were applied to Tethyan Permian corals [Belasky, 1994]. This last analysis suggested that the extreme eastern boundary of the Tethyan coral province should have been about 2000 km west of the North American craton at the paleoequator. For the interpreted latitude of the Eastern Klamath terrane at that time [Belasky and Stevens, 2006], that boundary would have been about 3000 km from the craton. Thus, the rare occurrence of Tethyan fossils in the McCloud Belt (e.g., the presence of the coral Waagenophyllum in the Middle Permian rocks in the Eastern Klamath terrane [Stevens et al., 1987]) suggests placement of this terrane on the order of 3000 km west of the craton if the Eastern Klamath terrane was at that latitude at that time.

METHODS This paper summarizes data from most if not all of the most important studies of fusulinid and colonial rugose coral faunas in the major outcrops of marine rocks of Permian age in western North America. In order to determine the relative importance of fusulinid genera in each of the major areas studied, all species listed in each area were tabulated. In cases where only the presence of genera was given, the number of species was considered to

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

280

Calvin H. Stevens and Paul Belasky

be one. Undoubtedly the data we present for fusulinids are incomplete as it is almost impossible to consider all publications because of the enormous amount of literature. We also encountered problems involving interpretation of the age of some species or genera listed by some workers. So, in a few cases we eliminated genera represented by species we consider to be Late Carboniferous in age, and we re-assigned some species and genera previously assigned to the Early Permian to the Middle to Late Permian and vice versa. Thus, some species may have been incorrectly eliminated and some others undoubtedly were overlooked. This method, however, should provide a reasonably accurate representation of the fusulinid faunas of each area by including data from reports on several different stratigraphic sections, possibly representing slightly different ages and environments. The colonial rugose coral faunas were much more easily tabulated because the distribution of species and genera of the entire Cordilleran-Arctic-Ural (CAU) realm was recently summarized by Fedorowski et al. [2007]. Finally, for the purpose of this paper, we place the Lower Permian-Middle Permian boundary at the top of the Kungurian [Jin Yugan, et al., 1997] or, in the Tethys, at the top of the Bolorian as suggested by Leven [1997].

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SCOPE OF PRESENT STUDY This paper summarizes the data and interpretations given in earlier works [e.g., Stevens et al., 1990; Belasky et al., 2002; Belasky and Stevens, 2006] with an updated species-based data base and a different treatment of the data in an attempt to look more critically into the composition of the most important elements of Permian faunas, not only in the allochthonous terranes, but also along the North American cratonal margin. Because fusulinids and colonial corals apparently are the most widespread of all faunal groups present in these rocks and have received the most attention, they will be the focus of our consideration here. Previous workers [e.g., Belasky et al., 2002] considered the presence or absence of genera and subjected those data to various statistical tests. Here, we will, in addition, consider diversity within genera. This type of analysis diminishes the significance of rare genera, but that is not entirely negative as such genera may simply be missing in some areas because of the paucity of sampling. We also will consider Early Permian and Middle to Late Permian faunas separately because in the CAU realm, colonial corals became extinct, and north of Texas fusulinids were exterminated at about the Early-Middle Permian boundary. Thus, analyses of these two parts of the Permian must be based upon different criteria.

EARLY PERMIAN FUSULINIDS Early Permian Fusulinids of the Craton Abundant Early Permian fusulinid faunas occur along much of the western margin of cratonal western North America. Seven areas (Fig. 1) where major faunal studies have been conducted are: (1) Texas [Dunbar and Skinner, 1937; Ross, 1960, 1962, 1963a; Ross and Ross, 2003; Williams 1963, 1966]; (2) Arizona-New Mexico [Sabins and Ross, 1963; Wilde,

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Nature of Permian Faunas in Western North America

281

2006]; (3) Nevada [Knight, 1956; Slade, 1961; Robinson, 1961; Rich, 1961; Cassity and Langenheim, 1966; Stevens et al., 1979]; (4) southeastern California (Bird Spring Shelf) [Stevens and Stone, 2007]; (5) east-central California (Conglomerate Mesa Uplift) [Magginetti et al., 1988; Stevens et al., 2001; Stevens and Stone, 2009a, b]; (6) cratonal western Canada (west-central Alberta) [Ross, 1967b; Ross and Bamber, 1978; Ross and Monger, 1978]; and (7) Canadian Arctic [Harker and Thorsteinsson, 1960; Nassichuk and Wilde, 1977; Rui et al., 1994]. The faunal data is presented in Table 1.

Texas In the well studied Early Permian faunas in Texas generic diversity is moderately high (Table 1). Species of Schwagerina are the most numerous. They are followed in numbers of species by Pseudoschwagerina, Parafusulina, Paraschwagerina, Stewartina, and long forms of Eoparafusulina (Table 1). Several species of Triticites also have been reported, but most may have been reworked from older beds. Arizona-New Mexico The faunas in Arizona and New Mexico have been shown to be moderately diverse (Table 1) based primarily on the work of Wilde [2006]. Species of Schwagerina are the most numerous followed in number of species by Pseudoschwagerina, Leptotriticites, and Pseudofusulina. The abundance of Leptotriticites and presence of several endemic genera, including Rugosochusenella, distinguish these faunas from those in Texas.

4 5?

3

2

3

1

Total Cratonic Canada#

10

1?

Arctic Canada

3

1 1

Western Canada

Nevada

1 1

3 5 9 5

Bird Spring Shelf, California

Advenella Biwaella Charaloschwagerina Crenulosepta Cuniculinella Eoparafusulina (long) Eoverbeekina? Inyoschwagerina Leptotriticites Nagatodarvasiella Nigribaccinus Oketaella Parafusulina s.l. Paraschwagerina Pseudochusenella Pseudofusulina Pseudofusulinella Pseudoschwagerina

Arizona and New Mexico

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Texas

Genus

Conglomera te Mesa, California

Table 1. Number of Early Permian Fusulinid Species on Cratonal North America

1

2

3

1 1

1 1

3 9 1

3? 9? 1

1 1

8 1

5 8 5 1 1 10

4

5 2 4

8 15

5

17 3 4 2 3 9

1 22

4 1 5

2 2

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Calvin H. Stevens and Paul Belasky

282

27

40

3 1

7 1

13 6*

3 2

Total Cratonic Canada#

14

Arctic Canada

26

Western Canada

Conglomera te Mesa, California

Nevada

Reticulosepta Rugosochusenella Rugosofusulina Rugososchwagerina? Schwagerina Sphaeroschwagerina Stewartina Triticites Boultonia Ozawainella Pseudoreichelina Pseudostaffella Schubertella Staffella

Bird Spring Shelf, California

Texas

Genus

Arizona and New Mexico

Table 1. Continued

10 1

8 3

17 3?

1

1 1 1

6 2 1 1 31 3 2 1 1 1

1 1 1 1

2 1

4

1

1 1

1 1

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* - some specimens may be reworked; # - total number of different species; ? - number of different species in question

California The California faunas are here divided into those of the Bird Spring Shelf [Stevens and Stone, 2007] and those present in the shallow-shelf deposits around the Conglomerate Mesa Uplift and the adjacent turbidite basins [Magginetti et al., 1988; Stevens et al., 2001; Stevens and Stone, 2009a, b] because our initial survey showed the faunas in the two areas to be quite dissimilar. In both areas, however, Schwagerina dominates in number of recorded species (Table 1). On the Bird Spring Shelf numbers of species of Schwagerina are followed in decreasing numbers of species by Leptotriticites, Stewartina, Parafusulina, and Pseudoschwagerina. In the outcrops around the Conglomerate Mesa Uplift, which include the westernmost fusulinidbearing Permian strata in cratonal North America, numbers of species of Schwagerina are followed by those of Parafusulina, Stewartina, Cuniculinella, and Pseudoschwagerina. Several species of Triticites have been reported, but as they occur in turbidites they may be reworked. Three endemic genera (Crenulosepta, Nigribaccinus, and Reticulosepta) and another genus, Inyoschwagerina, known elsewhere only from the Eastern Klamath terrane, are each represented by several species. Nevada The composition of the Nevada fusulinid fauna is similar to that in Texas in that the genera with largest numbers of species are similar (Table 1). Numbers of species of Schwagerina are followed by those of Parafusulina, Pseudoschwagerina, Pseudofusulina, Stewartina, long forms of Eoparafusulina, and Leptotriticites.

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Nature of Permian Faunas in Western North America

283

Canada In west-central Alberta along the Canadian cratonal margin, fusulinid faunas are much less abundant and diverse than farther to the south (Table 1). The meager faunas in Alberta are dominated by species of Schwagerina. In the Canadian Arctic diversity is moderately high and Schwagerina also is prominent. There, however, that genus is exceeded in importance by species of Pseudofusulinella. Species of the widespread Uralian-Tethyan genus Sphaeroschwagerina, which have not been recorded from the USA, also have been described from both western Canada and the Canadian Arctic. The total number of different species in cratonal Canada is shown in Table 1.

Early Permian Fusulinids in the Terranes

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McCloud Belt The McCloud Belt includes the Eastern Klamath terrane from which Skinner and Wilde {1965] described a vast number of fusulinid species; relatively small terranes in northwestern Nevada, east-central Oregon, northeastern Washington, and Black Mountain in northwestern Washington, the faunas of which were all described by Skinner and Wilde [1966]; the Stikine terrane, the faunas of which were studied by Pitcher [1960] and Ross and Monger [1978]; and the Quesnellia terrane, fusulinids of which were listed by Orchard and Danner [1991a] (Table 2). In total numbers of different species, Schwagerina and Pseudofusulinella are dominant in the McCloud Belt (Table 2). Also prominent among these faunas are species of Pseudofusulina, short forms of Eoparafusulina, Chalaroschwagerina, and Cuniculinella. Species of Parafusulina and Paraschwagerina also commonly occur in these faunas. The only completely endemic genus present apparently is Klamathina. Wrangellia Terrane The faunas from this terrane apparently are very sparse, but they are similar to those of the McCloud Belt, cratonal western Canada, and Arctic Canada in that species of Schwagerina and Pseudofusulinella are the most abundant (Table 2). Most of the other genera present in the McCloud Belt are not represented in the Wrangellia faunas. Eastern Tethyan Terranes A large number of genera (22) have been recorded from the Lower Permian rocks in the eastern Tethyan terranes (Table 3), but numbers of species are incompletely known. It appears, however, that species of Pseudofusulina may be the most abundant possibly followed by those of Triticites, Parafusulina and Sphaeroschwagerina. The presence of typical Tethyan genera not known in the other terranes or cratonal North America (e.g., Quasifusulina, Nagatoella, and Brevaxina) gives these faunas a special character.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

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Table 2. Number of Early Permian Fusulinid Species, McCloud Belt and Wrangellia Terrane

GENUS

Charaloschwagerina Cuniculinella Eoparafusulina (long) Eoparafusulina (short) Inyoschwagerina Klamathina Parafusulina s.l. Paraschwagerina Pseudofusulina Pseudofusulinella Pseudoschwagerina Quasifusulina Schwagerina Triticites Boultonia Schubertella Staffella

Skinner & Wilde, 1965

Skinner & Wilde, 1966

Skinner & Wilde, 1966

Skinner & Wilde, 1966

Pitcher, 1960; Ross, 1978

Orchard & Danner, 1991a

McCloud Belt, Eastern Klamath Mts. 4 9 2 18 4 3 1 6 25 28 2

McCloud Belt, NW Nevada

McCloud Belt, Oregon

McCloud Belt, Washington

McCloud Belt, Stikine terrane

6

1

McCloud Belt, Quesnellia terrane x

3

2

1 3

33 # # 3

2

4

5

2

# - genus added from Belasky et al. [2002] x - genus recorded as present ^ - total number of different species ? – total number of different species in question

# 1 1 1

7 # # 4 # 4 # 1 1

Petocz, 1970; Ross, 1978; Belasky et al., 2002

x

Total species in McCloud Belt^ 13? 9 3 20?

x # x x x

3 7? 7? 25? 33? 2?

# x # x

43 3? 3? 4? 1?

Wrangellia terrane

2

1

4 1 16

1

Nature of Permian Faunas in Western North America

285

Table 3. Number of Early Permian Fusulinid Species, Eastern Tethyan Terranes GENUS Acervoschwagerina Biwaella Brevaxina Charaloschwagerina Eoparafusulina Nagatoella Oketaella Parafusulina s. l. Paraschwagerina Pseudofusulina Pseudofusulinella Pseudoschwagerina Quasifusulina Robustoschwagerina Rugosofusulina Schwagerina Sphaeroschwagerina Triticites Codonofusiella Mesoschubertella Nankinella Schubertella

Ross & Ross, 1983; Orchard & Danner, 1991b x

Monger, 1975

x x x x x x x x x x x x x x x? x x

x 2 1 12 x x x x x 2 6 x x x

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x genus reported ? genus questioned

Relationships between Early Permian Fusulinid Faunas A substantial similarity is shown in the relative importance of the major genera reported along much of the cratonal margin of North America (Table 4). Species of Schwagerina are most numerous in all areas and those of Pseudoschwagerina and Stewartina are prominent all along the cratonal margin south of Canada. Parafusulina is also a prominent component in Texas, Nevada, and California. The most important genera of fusulinids in Texas and Nevada faunas are very similar (Table 4). The faunas in Arizona-New Mexico differ from those in Texas and Nevada in the presence of relatively large numbers of species of Leptotriticites and the lack of Early Permian species of Parafusulina, probably due to the paucity of fusulinid-bearing rocks of the appropriate age. Leptotriticites also is prominent on the Bird Spring Shelf in California, allying this fauna to that of Arizona-New Mexico. The faunas around the Conglomerate Mesa Uplift include an abundance of the genera Stewartina and Pseudoschwagerina, which allies them to all of the other cratonal faunas south of Canada. The relative abundance of species of Cuniculinella, and the presence of

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Calvin H. Stevens and Paul Belasky

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286

Inyoschwagerina and three endemic genera (Crenulosepta, Nigribaccinus, and Reticulosepta) (Table 1), however, differentiates this fauna from all others on the craton. Pseudofusulinella, which is well represented in the deep-water rocks in the Keeler Basin in the Conglomerate Mesa area, is prominent on the craton only in Canada; in the Canadian Arctic it is the dominant genus (Table 1). Thus, on the basis of the relative importance of genera, as measured by the number of species present (Table 4), we recognize five relatively distinct fusulinid assemblages in the Lower Permian rocks along the western margin of the North American craton. They are: (1) Arizona-New Mexico, (2) Texas-Nevada, (3) Bird Spring Shelf, California, (4) Conglomerate Mesa, California, and (5) Canada. Each of the terranes, including those comprising the McCloud Belt, the Wrangellia terrane, and the eastern Tethyan terranes, also have their own distinctive generic characteristics (Tables 2, 3). In the McCloud Belt the number of species of Schwagerina is followed by that of Pseudofusulinella, Pseudofusulina, short forms of Eoparafusulina, Chalaroschwagerina, and Cuniculinella. The presence of Pseudofusulinella allies this fauna to that of the Canadian Arctic and the Wrangellia terrane, and to some extent western Canada. The fauna of the Wrangellia terrane differs from that of the McCloud Belt in its very low diversity (Table 2). Diversity within most genera in the eastern Tethyan terranes is not known (Table 3). However, these faunas contain a relatively large number of genera unknown on the craton or in the other terranes. For faunal comparisons generic diversity is important because it can be interpreted as primarily reflecting water temperatures and the number of ecologic niches present. Therefore, the diversity of the fusulinid genera, excluding those belonging to the Families Staffellidae and Ozawainellidae, and the Subfamily Schubertellinae (following the taxomony of Bensh et al., 1996), hereafter referred to as “small” fusulinids, are given in Table 5. Members of the above mentioned taxa are not employed here for comparison because in some areas (e.g., the Bird Spring Shelf in California) some or all of these very “small” genera may have been overlooked or simply not reported. Table 4. Most Diverse Early Permian Fusulinid Genera in Cratonal Assemblages* California, Total Cratonal Conglomerate Canada Mesa Schwagerina Schwagerina Schwagerina Schwagerina Schwagerina Schwagerina Pseudoschwagerina Parafusulina s.l. Pseudoschwagerina Leptotriticites Parafusulina s.l. Pseudofusulinella Parafusulina s.l. Pseudoschwagerina Leptotriticites Stewartina Stewartina Pseudofusulina Paraschwagerina Pseudofusulina Pseudofusulina Parafusulina s.l. Cuniculinella Sphaeroschwagerina Stewartina Stewartina Paraschwagerina PseudoschwagerinaPseudoschwagerina Eoparafusulina Eoparafusulina Stewartina Pseudochusenella (long) (long) Leptotriticites Texas

Nevada

Arizona-New Mexico

California, Bird Spring Shelf

* in decreasing numbers of species

Table 5 shows that most of the areas on cratonal USA have similar moderately diverse faunas of “large” fusulinids ranging from 10 genera in Nevada to 14 in Texas. The generic diversity of the fauna at the Conglomerate Mesa Uplift, however, is high at 17, that of

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Nature of Permian Faunas in Western North America

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cratonal western Canada is low at 5, and that of the Canadian Arctic is 9. The generic diversity of “large” fusulinids in the terranes is equally broad, ranging from 5 in the Wrangellia terrane to 18 in the eastern Tethyan terranes. The fusulinid generic diversity of the Eastern Klamath terrane is 13. Table 5. Generic Diversity of “Large” Early Permian Fusulinids Region Arizona-New Mexico Texas Nevada Bird Spring Shelf, California Conglomerate Mesa, California Cratonal Western Canada Canadian Arctic Eastern Klamath Terrane Quesnellia Terrane Stikine Terrane Wrangellian Terrane Eastern Tethyan Terranes

Number of Genera 12 14 10 11 17 5 9 13 8 10 5 18

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EARLY PERMIAN COLONIAL RUGOSE CORALS Early Permian colonial rugose corals occur widely on the cratonal margin of North America, in several of the terranes belonging to the McCloud Belt, and in the Wrangellia terrane. The eastern Tethyan terranes, in contrast, have not yielded any Early Permian colonial corals, although one species is known from clasts in a Triassic conglomerate in Oregon [Belasky and Stevens, 2006]. Presumably these clasts were eroded out of an eastern Tethyan terrane.

Colonial Rugose Corals on the Craton For our analyses the number of species of colonial rugose corals has been tabulated (Table 6) for four cratonal areas (Texas, Cordilleran miogeocline in California and Nevada, western Canada, and Canadian Arctic Islands), the major terranes of the McCloud Belt (Stikine and Eastern Klamath terranes), and the Wrangellia terrane based on data from Fedorowski et al. [2007] and Stevens [2008a, b].

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers, Incorporated, 2009.

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Table 6. Number of Early Permian Colonial Rugose Coral Species and Generic Diversity*

GENUS

Cordillerastraea Cystolonsdaleia Durhamina Fomichevella Heintzella Iskutella Kleopatrina Langenheimia Lytvophyllum Paraheritschioides Pararachnastraea Permastraea Petalaxis Protolonsdaleiastraea Protowentzellela Pseudocystophora Sandolasma Shastalasma Tschussovskenia Wilsonastraea Generic diversity

Texas

Miogeocline, Nevada & California

Western Canada

2 1

1 1

1

Cratonal Total

1

3 6 5 5 7

6 4 4

1 1

3 2

4

2

4

5 3 5 4

1

3

1

8 1 5 2 2 3

6

15

5

2

Canadian Arctic

*Data from Fedorowski [2002]; Stevens [2008a, b] #Total number of different species

3 2 5 3 8 2

1

11

5 5 7 4 3 8 2 7 2 3 3 16

Stikine terrane

2 1 2 1 2 1 4 5 1 2 1

Eastern Klamath terrane

1 3

1 3 1 1 2 3 4

McCloud Belt total#

3 4 2 1 3 3 2 4 5 4

Wrangellia terrane

1

1

1 1 1

2 1

5 1 2 1

3

3

4

3

7

1

12

13

16

8

1 1

Nature of Permian Faunas in Western North America

289

Of the areas on the North American craton where Early Permian colonial corals occur, only the Cordilleran miogeocline and the Canadian Arctic contain highly diverse faunas (Table 6). In the Cordilleran miogeocline species of Protowentzelella and Durhamina dominate followed by species of Sandolasma, Permastraea, and Paraheritschioides, with a moderate representation of Petalaxis, Kleopatrina, Fomichevella, and Heintzella (Tables 6, 7). Two genera (Shastalasma and Petalaxis) are not reported from elsewhere in cratonal North America, and Sandolasma and Wilsonastraea are known elsewhere on the craton only in Texas. Table 7. Most Diverse Early Permian Coral Genera* Cordilleran Miogeocline, Nevada & California Protowentzelella Durhamina Sandolasma Permastraea Paraheritschioides

Canadian Arctic Protowentzelella Permastraea Kleopatrina Fomichevella Paraheritschioides Protolonsdaleiastraea

Stikine terrane Paraheritschioides Wilsonastraea Lytvophyllum

Eastern Klamath terrane Petalaxis Durhamina Pararachnastraea Wilsonastraea Shastalasma Kleopatrina

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* in decreasing number of species

The Canadian Arctic fauna is quite different from that of California and Nevada, being dominated by Protowentzelella followed by Permastraea and Kleopatrina. Other moderately important genera in this region are Fomichevella, Paraheritschioides, and Protolonsdaleiastraea, a genus unknown elsewhere on the craton. In the western Canadian fauna only Protowentzelella and Kleopatrina are represented by more than one species and this fauna differs from that in the Canadian Arctic in being generically much less diverse, containing the genus Durhamina, which is common along the cratonal margin to the south, and lacking Protolonsdaleiastraea. Only six genera, most represented by only one species and all of which also occur in the Cordilleran miogeocline, are present in Texas (Table 6). No Permian colonial corals are known from Arizona or western New Mexico. Thus, on the basis of the above observations, we consider that the four Early Permian cratonal coral faunal assemblages (in Texas, the Cordilleran miogeocline of Nevada and California, western Canada, and Arctic Canada) are distinct.

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Table 8. Genera Absent from Major Colonial Coral Faunas

GENUS Cordillerastraea Cystolonsdaleia Durhamina Fomichevella Heintzella Iskutella Kleopatrina Langenheimia Lytvophyllum Permastraea Petalaxis Protolonsdaleiastraea Protowentzellela Pseudocystophora Sandolasma Shastalasma Tschussovskenia Wilsonastraea 0 indicates absence of that genus

Cordilleran miogeocline, Nev. & Calif. 0

Canadian Arctic

Eastern Klamath terrane 0

Stikine terrane

Quesnellia terrane

Wrangellia terrane

0

0

0 0

0 0 0 0

0

0

0 0

0 0

0

0

0 0 0 0 0 0

0

0

0 0 0 0 0

0 0 0 0 0 0

0 0

0

0 0

0 0

0

0 0 0 0 0 0 0 0 0 0 0

Nature of Permian Faunas in Western North America

291

Colonial Rugose Corals in the Terranes Among the terranes only the Stikine and the Eastern Klamath terranes contain relatively diverse colonial coral faunas; very few corals are known from the Quesnellia terrane, which has not been well studied, and the Wrangellia terrane. The faunas in the Stikine and Eastern Klamath terranes are similar in some respects, but are quite different in detail (Tables 6, 7). In the Eastern Klamath terrane species of Petalaxis are the most numerous followed by those of Durhamina, Pararachnastraea, Wilsonastraea, Shastalasma, and Kleopatrina (Table 7). Among the most diverse genera in the Stikine terrane, Lytvophyllum, Iskutella, Fomichevella and Cystolonsdaleia replace Durhamina, Pararachnastraea, Shastalasma and Kleopatrina in the Eastern Klamath terrane in importance (Tables 6, 7). The few corals reported from the Quesnellia terrane are similar to those in other parts of the McCloud Belt (Table 8). The fauna of the Wrangellia terrane is slightly less sparse, with eight genera represented by one species each (Table 6). All genera in this terrane also are present in the McCloud Belt (Table 8). Thus, although there are differences between the faunas of these four terranes (Eastern Klamath, Quesnellia, Stikine, and Wrangellia), there are also important similarities (e.g., the presence of Lytvophyllum, which is unknown on the North American craton).

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Relationships between Early Permian Colonial Rugose Coral Faunas The lists of the most diverse genera in the four most diverse Early Permian faunas (the Cordilleran miogeocline, Canadian Arctic, Eastern Klamath terrane, Stikine terrane) are considerably different (Table 7). Further comparison of the entire fauna for the North American craton with the entire fauna reported from the terranes emphasizes some significant differences considered here to be important. As shown on Table 8, four genera (Sandolasma, Cordillerastraea, Tschussovskenia, and Permastraea) are restricted to the craton. Another four genera (Iskutella, Langenheimia, Lytvophyllum, and Cystolonsdaleia) are restricted to the terranes. Of the genera restricted to the terranes (Table 9) all four occur in both the Eastern Klamath and Stikine terranes, and two of the four are recorded from both the Quesnellia and Wrangellia terranes. Table 9. Coral Genera Restricted to Non-Tethyan Terranes

Cystolonsdaleia Iskutella Langenheimia Lytvophyllum

Eastern Klamath terrane x x x x

Quesnellia terrane x

x

Stikine terrane

Wrangellia terrane

x x x x

x x

x genus present

The Early Permian faunas on the craton span about 40˚ of latitude from Texas to the Canadian Arctic. As latitude imposes important constraints on the distribution of animals of

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Calvin H. Stevens and Paul Belasky

292

all types, we have attempted to ascertain the importance of latitude in controlling the distribution of colonial rugose corals by comparing those occurring at different latitudinal positions on the craton. The only diverse faunas known along the cratonal margin are those of the Cordilleran miogeocline, which was at low latitudes (about 8˚ to 15˚), and the Canadian Arctic, which was located at relatively high latitudes (35˚ to 40˚). Thus, a comparison of these two faunal assemblages is used as a starting point for consideration of the significance of latitude in development of Early Permian colonial coral faunas. Our data show that, on the craton, five genera (Durhamina, Sandolasma, Wilsonastraea, Shastalasma, and Petalaxis) do not occur in the Canadian Arctic, whereas Protolonsdaleiasteraea, which is known from the Canadian Arctic, is not present elsewhere on the craton (Table 10). These genera, therefore, are here considered to be latitudinally restricted and are here referred to as miogeocline-indicative and Arctic-indicative genera. Further comparisons show that one genus in the miogeocline (Sandolasma) occurs elsewhere only in Texas. This genus therefore is interpreted to have been confined to the most southerly parts of the craton, here referred to as the equatorial belt. Two other genera (Petalaxis and Shastalasma), both missing from the Canadian Arctic, western Canada, and Texas, apparently overlap the equatorial belt but are restricted to higher latitudes than Texas and lower latitudes than western Canada. As mentioned previously, Protolonsdaleiastraea is confined to the high latitudes of the Canadian Arctic.

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Durhamina Petalaxis Protolonsdaleiastraea Sandolasma Shastalasma Wilsonastraea

x

x x

x

x x

x

x x x

x x x

x x

x

Wrangellia terrane

Stikine terrane

Quesnellia terrane

Eastern Klamath terrane

Canadian Arctic

Western Canada

Cordilleran miogeocline, Nev. & Calif.

Texas

Table 10. Distribution of Latitude-Sensitive Coral Genera

x x x

x x

x

x

x genus present

INTERPRETATIONS OF EARLY PERMIAN FAUNAS Data from fusulinid and colonial rugose coral faunas both contribute to the understanding of the paleobiogeography of the eastern Paleopacific Ocean in the Early Permian. Both groups of fossils also provide data relevant to interpretation of environmental conditions on cratonal North America and the terranes, and on the relationships between the faunal assemblages in different places.

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Nature of Permian Faunas in Western North America

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Fusulinid Faunas The fusulinid assemblages that developed at different latitudes along the cratonal margin of North America differ somewhat in detail. Some of the differences probably are due to differences in water temperature at different paleolatitudes, but others may be due to other environmental factors. The diversity of genera in Arizona-New Mexico and the Bird Spring Shelf (Table 5), both of which lay a little north of the paleoequator between about 2˚N and 15˚N is similarly modest. Perhaps this was due to similar numbers of somewhat different ecologic niches, resulting in the observed differences in the diversity of species within different genera (Table 4). The fusulinid faunas in Nevada are much more similar to those in Texas than those of the geographically closer Bird Spring Shelf (Table 4), probably because the most important environmental conditions affecting these fossils were very similar in the two areas. The Texas faunas are more diverse than those of Nevada, however, possibly because this area was at a lower latitude. The Conglomerate Mesa Uplift has the most diverse fauna of any part of the craton (Table 5), probably because it not only lay at a relatively low latitudinal position and had a rugged irregular coastline so that there were numerous ecological niches, but also because as an island in the open ocean, it was farther away from fresh-water and nutrient influx. In addition, foreign genera evidently were able to immigrate from distant terranes, especially from the Eastern Klamath terrane. This is indicated by the presence of two important Eastern Klamath terrane genera in the Conglomerate Mesa area– Cuniculinella, which elsewhere is represented by only one species on the Bird Spring Shelf, and Inyoschwagerina, which elsewhere occurs only in the El Paso Mountains, another island that lay offshore from the Bird Spring Shelf during the Early Permian. The low diversity of the western Canadian cratonal faunas (Table 5) may in part be due to their higher latitude (about 25˚N) and in part due to lack of appropriate facies. The moderate diversity of the Canadian Arctic faunas is higher than expected, considering the high latitudes (35˚ to 40˚N). The paucity of Pseudoschwagerina and lack of Stewartina in Canada, however, probably reflects cooler water temperatures at these relatively high latitudes. Two genera, Leptotriticites and Pseudofusulinella, have somewhat unusual distributions, probably due to similar specific environmental constraints. Leptotriticites is most important in Arizona-New Mexico and the Bird Spring Shelf in California (Table 4). This genus may have preferred the more open marine water on shelves that faced the open ocean. Pseudofusulinella, which is dominant in the Canadian Arctic and important in the Eastern Klamath terrane, the Wrangellia terrane, western Canada, and the deep-water turbidites in the Conglomerate Mesa area, may have preferred relatively cool water. Of considerable interest is the question of the relationships between the fusulinid faunas of the allochthonous terranes (those of the McCloud Belt, Wrangellia terrane, and eastern Tethyan terranes) and the cratonal faunas of western North America. As shown in Tables 1-3, faunas from all of these areas differ considerably, although there are some similarities. The greatest similarity between fusulinid faunas of the McCloud Belt and cratonal North America is that between the faunas of the Eastern Klamath terrane and cratonal California. Even here, however, the similarity is only moderate with Jaccard and Otsuka coefficients of similarity of 0.42 and 0.59, respectively, for the Conglomerate Mesa fauna, and 0.35 and 0.53 for the Bird Spring Shelf. For comparison, Jaccard and Otsuka similarity coefficients calculated for the Bird Spring Shelf and the Conglomerate Mesa Uplift are 0.50 and 0.69,

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respectively, indicating high similarity for these areas that were located relatively close to one another, but probably with some significantly different ecologic niches. The generic diversity of the “large” Eastern Klamath fusulinids (13 genera) is similar to that of the Bird Spring Shelf faunas (11 genera), but lower than that of the Conglomerate Mesa faunas and much higher than that of the cratonal Canadian faunas (Table 5). The faunal diversity of other parts of the McCloud Belt is lower than that of the Eastern Klamath terrane: that of the Stikine terrane is 10 and that of the poorly studied Quesnellia terrane is only 8. It seems probable that there were numerous ecologic niches around all of the terranes of the McCloud Belt, as they consisted of islands located in the open ocean. The fusulinid diversity, therefore, would be expected to be equivalent to that of Conglomerate Mesa unless the diversity in these terranes, including that of the relatively diverse Eastern Klamath terrane, was constrained by some other environmental factors, perhaps water temperatures lower than that around Conglomerate Mesa. The generic diversity of the fusulinid faunas in the Stikine terrane, which is lower than that of the Eastern Klamath terrane, could be due to even lower water temperatures. The diversity of Wrangellia terrane genera, which is very low (5 genera), even lower than that of the Canadian Arctic, may in part be due to the general lack of appropriate facies, but it still implies relatively cool water. The composition of the Wrangellian fusulinid fauna, meager as it is, is most similar to that of western Canada (Tables 1, 2). The generic diversity in the eastern Tethyan faunas (18 genera of “large” fusulinids) is very high, similar to that at Conglomerate Mesa, suggesting that both areas were surrounded by warm water at low latitudes. A relatively large number of the Early Permian genera in the eastern Tethyan terranes are unknown in cratonal North America and in the other terranes (Tables 1-3). Thus, the overall composition of the eastern Tethyan faunas suggests that the positions of these terranes during the Early Permian were distant from not only North America, but also the McCloud Belt and the Wrangellia terrane.

Colonial Rugose Coral Faunas The generic diversity of colonial corals on the craton is variable (Table 6) being highest in the miogeocline (15), followed by the Canadian Arctic (11), Texas (6), and western Canada (5). The low diversity in Texas is surprising considering its low paleolatitudinal placement, so other environmental factors must have been important. As modern corals are very sensitive to high water temperatures [Glynn, 1991], the paucity of Permian corals in Texas may have been due to relatively high water temperatures in this restricted tropical sea. The low diversity in western Canada may be due to the general lack of exposure of favorable facies. As shown by the distribution of genera of colonial rugose corals on the craton, some are cosmopolitan, whereas others are restricted to specific latitudes, probably because of differences in the water temperatures. Temperature-sensitive genera, therefore, can be used for interpretation of the latitudinal placement of the terranes during the Early Permian. The Eastern Klamath terrane contains four of the five miogeocline-indicative coral genera, lacking only Sandolasma (Table 10). It also lacks Protolonsdaleiastraea, the Arcticindicative genus. Thus, this fauna is allied to that of the miogeocline. The poorly studied Quesnellia terrane has yielded only two miogeocline-indicative genera (Wilsonastraea and Petalaxis), but it also lacks Protolonsdaleiastraea. The Stikine

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Nature of Permian Faunas in Western North America

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terrane has three miogeocline-indicative coral genera (Durhamina, Wilsonastraea, and Petalaxis), but it also contains Protolonsdaleiastraea. The Wrangellia terrane, which also contains Protolonsdaleiastraea, has only two miogeocline-indicative genera (Durhamina and Wilsonastraea). The progressive decrease in miogeocline-indicative species from the Eastern Klamath terrane, through the Quesnellia and Stikine terranes, to the Wrangellia terrane, and the appearance of Protolonsdaleiastraea in the two latter terranes suggest increasingly higher latitudes. The only Early Permian Tethyan colonial coral in western North America, which occurs in pebbles in a Triassic conglomerate in central Oregon [Belasky and Stevens, 2006], belongs to a different family (the Waagenophyllidae) from all other Early Permian colonial corals in North America. These coral specimens, however, are similar to species of the Asiatic genus Yokoyamaella, thus suggesting an origin from one of the eastern Tethyan terranes, which themselves probably were far removed from cratonal North America and the other terranes in the Early Permian.

PLACEMENT OF TERRANES IN THE EARLY PERMIAN

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Latitudinal Placement The terranes under consideration can be placed latitudinally on the basis of the fusulinids and corals present, assuming that water temperatures, which almost surely decreased northward, played a significant role in determining the faunas present. Thus, a moderately high latitudinal position for the central Stikine terrane is suggested by the relatively low diversity of fusulinids, the presence of three miogeocline-indicative colonial coral genera, and the occurrence of the Arctic-indicative coral genus Protolonsdaleiastraea. This position is completely compatible with the paleomagnetic data which show that the central part of the Stikine terrane was at a position of about 23˚N [Irving and Monger, 1987] in the Early Permian. Thus, all data suggest placement of the central part of the Stikine terrane at a little higher latitude than that of the Canada-USA border (Fig. 2). The Eastern Klamath terrane has a higher diversity of both fusulinids and colonial corals than the Stikine terrane, has more miogeocline-indicative colonial coral genera, and lacks the Arctic-indicative coral Protolonsdaleiastraea. Therefore, it should be placed south of the central part of the Stikine terrane. Although the coral fauna of the Eastern Klamath terrane is rather closely allied to that of the Cordilleran miogeocline, it lacks Sandolasma (an equatorial coral) and the diversity of fusulinid genera is slightly lower than in the miogeocline. Therefore, this terrane is placed at a higher latitude than that of the miogeocline in Nevada. A position at the latitude of Oregon (Fig. 2) seems most reasonable. The fauna of the Quesnellia terrane is not well known. It has a lower fusulinid diversity than that in either the Stikine or Eastern Klamath terrane, and it contains only two of the miogeocline-indicative coral genera. However, it lacks Protolonsdaleiastraea. Therefore, based on these meager data, and an important Middle Permian fauna from this terrane (see later), the Quesnellia terrane was tentatively placed between the central part of the Stikine terrane and the Eastern Klamath terrane (Fig. 2). I now would place this terrane slightly south of that shown in Figure 2.

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Calvin H. Stevens and Paul Belasky

296

Canadian Arctic Islands 7

Yukon

CANA DA USA B.C.

30 N W A

Edge of Cratonal North America

6 X

Al.

Sask.

Q X

MT EK

S

ID

15 N

WY

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3 UT

NV

5

CO

4 CA

1000 km

AZ

US

A

NM 2 1

0 N MEXICO

Figure 2. Interpreted Early Permian latitudinal positions of major terranes relative to cratonal North America: EK=Eastern Klamath terrane; Q=Quesnellia terrane; S=Stikine terrane; W=Wrangellia terrane in mainland Alaska. X marks the location of Permian corals [Stevens and Rycerski, 1983] and paleomagnetic data [Irving and Monger, 1987] in the Stikine terrane, and paleomagnetic data [Butler et al., 1997] in the Alexander terrane. Paleolatitudes for cratonal North America in the Artinskian are from Scotese and McKerrow (1990); paleolongitudes are not implied. See Figure 1 for keys to numbers.

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Nature of Permian Faunas in Western North America

297

The Wrangellia terrane in Alaska has a lower diversity of coral genera than that of the Stikine terrane, it contains only two miogeocline-indicative coral genera rather than three as in the Stikine terrane, and it also contains Protolonsdaleiastraea. Therefore, this part of the Wrangellia terrane belongs north of the Stikine terrane. The presence of two miogeoclineindicative colonial corals, however, also suggests placement well south of the Canadian Arctic. Paleomagnetic data from the central Alexander terrane, with which the Wrangellia terrane is amalgamated, indicates a latitude of 25-30˚N [Butler et al., 1997]. This then places the part of the Wrangellia terrane in mainland Alaska at 32˚N, at about the latitude of the British Columbia-Yukon Territory border. This position north of the Stikine terrane is compatible with the data on the colonial corals. Finally, the high diversity of fusulinid genera in the eastern Tethyan terranes suggests an equatorial position in the Early Permian.

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Longitudinal Placement Longitudinal placement of the terranes is much more speculative than latitudinal placement. Otsuka similarity coefficients derived from fusulinid data from the miogeocline in Nevada and California and the Eastern Klamath terrane are moderate, suggesting a separation of more than 1600 km distance. Other statistical data used for comparing the coral faunas of eastern California and the Eastern Klamath terrane suggest a separation on the order of 3000 km [Belasky and Stevens, 2006]. The distribution of important coral genera tends to suggest, in accordance with previous statistical analyses [e.g., Belasky et al., 2000], that all of the terranes under consideration were separated from the craton by considerable distances. Four genera, Sandolasma, Cordillerastraea, Tschussovskenia, and Permastraea, are restricted to the craton, whereas four others, Iskutella, Langenheimia, Lytvophyllum, and Cystolonsdaleiea, are restricted to the non-eastern Tethyan terranes (Table 6, 9). Of the genera restricted to the non-Tethyan terranes, Iskutella and Lytvophyllum occur in both the McCloud Belt and the Wrangellia terrane. Two other genera, Langenheimia and Cystolonsdaleia, however, are restricted to the McCloud Belt (Table 9). This tends to suggest some separation between the McCloud Belt and the Wrangellia terrane during the Early Permian. On the basis of the substantial difference between the fusulinid faunas of the eastern Tethyan terranes and those of the North American craton, the McCloud Belt, and the Wrangellia terrane, the eastern Tethyan terranes are interpreted to have been situated far from cratonal North America and the other terranes in the Early Permian. The almost total difference in the coral faunas between those in the Tethyan realm and those along the North American cratonal margin and in the non-eastern Tethyan terranes also suggests that the eastern Tethyan terranes were situated far out in the Paleopacific Ocean during the Early Permian.

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FAUNAL CHANGES FROM EARLY TO MIDDLE PERMIAN

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A change in both fusulinid and colonial rugose coral faunas between the Early and Middle to Late Permian on both the North American craton and in the non-eastern Tethyan terranes was profound. In both cratonal North America and these terranes, colonial corals of the Cordilleran-Arctic-Ural (CAU) realm became extinct, the extinction progressing from north to south along the cratonal margin [Fedorowski et al., 2007]. Simultaneously, fusulinids were exterminated from the Wrangellia terrane and the North American craton, except for Texas and nearby areas. The diversity of fusulinids in the McCloud Belt was greatly reduced and, except for several “small” fusulinids in the Quesnellia terrane, Parafusulina is the only genus represented. These major faunal changes have been interpreted as due to a cooling of the climate beginning in the latter part of the Early Permian which is especially well illustrated in the rocks in northwestern Pangaea, as documented by Beauchamp and Desrochers [1977]. These writers found that in the Asselian and Sakmarian (early Early Permian), a succession of limestones bearing calcareous algae and foraminifera, interpreted as recording warm-water environments, were deposited. This was followed in the Artinskian (middle Early Permian) by carbonates bearing bryozoans and echinoderms, interpreted to represent cool to locally warm-water environments. Later, in the Kungurian (late Early Permian) and later, the waters became progressively colder and chert was deposited. A similar general change in faunas also is recorded in the miogeocline in Nevada where Lower Permian rocks bearing colonial rugose corals and fusulinids were succeeded by Middle Permian units bearing bryozoan and brachiopod faunas [Wardlaw, 1980]. Wardlaw also attributed this change to a decrease in water temperatures at least as far south as the Cordilleran miogeocline.

MIDDLE TO LATE PERMIAN FUSULINIDS The fusulinid faunas in Texas and to the west in Arizona and New Mexico, the only region on the North American craton bearing Middle to Late Permian fusulinids, are moderately diverse (11 counting all genera). These faunas are dominated by Parafusulina (Table 11). Other prominent genera include the endemic Polydiexodina and the “small” fusulinids Reichelina, Codonofusiella, and Rauserella of Tethyan affinity. The fauna in the McCloud Belt is very restricted, consisting of species of Parafusulina and, at one locality in the Quesnellia terrane, several “small” fusulinids, including Pseudokahlerina, Minojapanella, Dunbarula, and Boultonia (Table 11), which have a Tethyan affinity. The Late Permian fusulinid faunas from the eastern Tethyan terranes, in contrast to those of Texas and the McCloud Belt, are very rich with a total of at least 32 genera, including “small” fusulinids (Table 12). Although the generic compositions of these faunas are known, the numbers of species in the most important areas have not been published. It appears, however, that species of Yabeina are dominant, perhaps followed by Neoschwagerina, Schwagerina, Chusenella and Pseudodoliolina (Table 12). Among these “large” genera, only Yabeina, occurs on the craton, and it is only represented by a single, unusually small species

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Nature of Permian Faunas in Western North America

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in Texas. “Large” Tethyan genera do not occur any where else on the craton or in any of the non-eastern Tethyan terranes. Table 11. Number of Middle and Late Permian Fusulinid Species, Cratonal North America and Mccloud Belt Arizona-New Mexico

Texas Ross, 1963b; Wilde & Rudine, 2000; Yang &Yancey, 2000 24 4 1 1

Ross & Tyrell, 1965; Sabins & Ross, 1963 Parafusulina Polydiexodina Yangchienia Yabeina Boultonia Codonofusiella Dunbarula Minojapanella Paraboultonia Paradoxiella Pseudokahlerina Rauserella Reichelina Schubertella Staffella

3

Eastern Klamath terrane Coogan, 1960; Skinner & Wilde, 1965 8

Quesnellia terrane Orchard & Danner, 1991a 1

1 4 1 1 1 1 1 3 6 2 1

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Table 12. Number Of Middle And Late Permian Fusulinid Species Cited, Eastern Tethyan Terranes

GENUS Acervoschwageri na Afghanella Brevaxina Cancellina Chusenella Metadoliolina Misellina Monodiexodina Nagatoella Neoschwagerina Parafusulina s.l. Pseudodoliolina Pseudofusulina Schwagerina Sumatrina? Verbeekina

California

Oregon

Washington

Alaska

Douglass, 1967; Stevens et al., 1991

Bostwick & Nestell, 1967

Skinner & Wilde, 1966; Ross & Ross, 1983

Stevens et al., 1997

British Columbia Monger, 1969; Monger & Ross, 1971; Monger, 1975

x x x x

x 1 4

1

x

x

x x

1

x 3

3

x

1

5

3

5+ 2+ 2+ x 1+

1+ x 1

1 1

1 1

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Table 12. Continued

GENUS Yabeina Yangchienia Boultonia Codonofusiella Dunbarula Kahlerina Minojapanella Nankinella Ozawainella Parareichelina Pseudokahlerina Rauserella Reichelina Schubertella Sphaerulina Staffella

California

Oregon

Washington

Alaska

Douglass, 1967; Stevens et al., 1991

Bostwick & Nestell, 1967

Skinner & Wilde, 1966; Ross & Ross, 1983 12

Stevens et al., 1997

x x x x x? x 1

x

x x 1

2

1 1 1 1

British Columbia Monger, 1969; Monger & Ross, 1971; Monger, 1975 3+ x x x x x x x x

1 x 1 1 1 1

x

x x x x x

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x - genus present x? - genus questionably present + - number uncertain, probably higher

A comparison of Late Permian fusulinids from the three faunal belts in North America points up considerable differences (Tables 11, 12). The faunas of Texas and the McCloud Belt are both dominated by Parafusulina and in both areas (in Texas and in the Quesnellia terrane) several genera of “small” fusulinids of Tethyan affinity are present. The faunas in Texas differ from those in the McCloud Belt, however, in that the Texas faunas contain the endemic genus Polydiexodina and a very small endemic species of the Tethyan genus Yabeina. In addition, the “small” fusulinid genera present in the two areas are different. The faunas from the eastern Tethyan terranes differ from those of Texas and the McCloud Belt in being very diverse and containing numerous “large” fusulinid genera.

MIDDLE TO LATE PERMIAN COLONIAL RUGOSE CORALS Middle to Late Permian colonial rugose corals are rare in western North America and no colonial corals of this age have been found in cratonal North America. The CordilleranArctic-Ural (CAU) colonial coral lineages, which were widespread on the margin of cratonal North America during the Early Permian, had become extinct prior to the beginning of the Middle Permian [Fedorowski et al., 2007]. Two colonial corals have been recovered from the McCloud Belt, however, both waagenophyllids of Tethyan affinity. These are a species of Miyagiella from the Quesnellia terrane [Nelson and Nelson, 1985], where it is associated with several fusulinids of Tethyan

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Nature of Permian Faunas in Western North America

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affinity, and Waagenophyllum klamathensis, which was described from the Eastern Klamath terrane by Stevens et al. [1987]. In the eastern Tethyan terranes, only a few corals, all waagenophyllids, have been reported. One is Waagenophyllum klamathensis, which occurs in blocks in the western Klamath Mountains where it is associated with Tethyan fusulinids [Stevens, 1987], and a different species of Waagenophyllum in the southern part of the Tethyan Cache Creek terrane in British Columbia [Stevens, unpub. data]. Other colonial corals, probably waagenophyllids of Tethyan affinity from the northern part of the Cache Creek terrane, also have been mentioned by Monger [1969].

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PLACEMENT OF TERRANES IN THE MIDDLE PERMIAN The lack of fusulinid and colonial coral faunas on cratonal North America north of the latitude of Texas is interpreted to be the result of waters too cold for survival of those taxa. The presence of gigantic species of Parafusulina in the McCloud Belt, “small” fusulinids and a colonial coral with warm–water Tethyan affinities in the Quesnellia terrane, and another warm-water colonial coral in the Eastern Klamath terrane, therefore, presents a problem. If the terranes had not moved from the latitudes of Oregon to British Columbia since the Early Permian they would have been bathed by cool water and should not contain fusulinids and colonial corals. Therefore, we suggest that at least parts of the McCloud Belt (Eastern Klamath and Quesnellia terranes) were located south of the Cordilleran miogeocline in the Middle to Late Permian where the waters were warmer. Sparse paleomagnetic data for Middle to Late Permian rocks, suggesting a more southerly location of the non-eastern Tethyan terranes, are consistent with the interpretations of placement of terranes based on the coral and fusulinid faunas. Paleomagnetic data from the Eastern Klamath terrane suggest that this terrane lay at the latitude of western USA throughout its history, which goes back to the Neoproterozoic [Mankinen et al., 2002], but for the Middle to Late Permian, Mankinen and Irwin [1990] indicated a paleolatitude of 8˚ to 28˚N. On the basis of the presence of fusulinids and one species of colonial coral, we have elected to place the Eastern Klamath terrane at about 8˚N, at about the paleolatitude of northern Baja California, which is within the margin of error for the paleomagnetic data. The fusulinids and the single colonial coral in the Quesnellia terrane also requires us to place this terrane south of the Cordilleran miogeocline in the latter part of the Permian. Now I would place Quesnellia slightly south of the position shown in Figure 3, Paleomagnetic data from Lower Permian rocks in the central part of the Alexander terrane were indicated as 25˚ to 30˚N in the Early Permian, but 10˚ to 20˚N in the Late Triassic [Butler et al., 1997], representing a significant displacement of this terrane and the attached Wrangellia terrane during the intervening time. Panuska and Stone [1985] indicated a placement of the Wrangellia terrane at 8˚±6˚N for Upper Permian rocks, suggesting that displacement occurred in about Middle Permian time. Thus, it appears possible that the composite Wrangellia-Alexander terrane was displaced southward along with the terranes of the McCloud Belt, in latest Early or earliest Middle Permian time. On the assumption that the Wrangellia-Alexander terrane moved with the McCloud Belt, the central part of the

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Calvin H. Stevens and Paul Belasky

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Alexander terrane falls at about 16˚N (Fig. 3). This is within the limits of the data on Upper Triassic rocks presented by Butler et al. [1997]. This placement of the Alexander terrane requires the Wrangellia terrane to be placed at about 20˚N, however, somewhat north of the limits indicated by Panuska and Stone [1985] for the Upper Permian rocks they studied. Canadian Arctic Islands 7

Yukon

CANA DA USA

Early Permian position relative to North America

B.C.

W 30 N Edge of Cratonal North America

6

Al.

Sask.

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MT

ID WY W 3

15 N

A

UT

NV

5

CO

4 CA

AZ

NM

Q US

A

2 1

S EK

0 N

MEXICO

1000 km

Figure 3. Interpreted Middle Permian (Kazanian) latitudinal positions of major terranes. Paleolatitudes for cratonal North America are from Scotese and McKerrow (1990); paleolongitudes are not implied. See caption for Figures 1 and 2 for keys to numbers and letters.

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Nature of Permian Faunas in Western North America

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The presence of giant species of Parafusulina both on the craton in Texas and in the McCloud Belt also suggests that the McCloud Belt was closer to cratonal North America in the Middle Permian than in the Early Permian. The occurrence of the same coral species, W. klamathensis, in both the Eastern Klamath terrane and in Tethyan blocks in the western Klamath Mountains, and the presence of fusulinids and a coral with Tethyan affinities in the Quesnellia terrane suggest that the McCloud Belt and at least some of the eastern Tethyan terranes were closer together in the Middle to Late Permian than in the Early Permian. The presence of fusulinids of Tethyan affinity on the craton in Texas also points to the possibility that the Tethyan province had expanded farther eastward in the latter part of the Permian perhaps due to eastward movement of some of the eastern Tethyan terranes toward cratonal North America in Middle to Late Permian time. The high diversity of “large” fusulinid genera in the eastern Tethyan terranes, the total lack of these genera in the McCloud Belt and the Wrangellia terrane, and the presence of only one species representing one of the genera in cratonal North America (Texas), however, strongly suggest that the faunas of the eastern Tethyan terranes were carried far across the Paleopacific Ocean on terranes rather than representing dispersal of these faunal elements during the Permian as indicated by Newton [1988].

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CONCLUSION Various comparisons of the Early Permian colonial rugose coral and fusulinid faunas and statistical tests based on these faunas indicate that the McCloud Belt and the Wrangellia terrane lay somewhat offshore from cratonal North America (perhaps on the order of 20003000 km) during the Early Permian, as suggested by Belasky and Stevens [2006]. These faunas also suggest that the Eastern Klamath terrane was at the latitude of Oregon at that time. The fusulinids and colonial rugose corals, as well as the paleomagnetic data from the central part of the Stikine terrane and the Alexander terrane, indicate that the Stikine terrane lay north of the Eastern Klamath terrane and that the Wrangellia terrane was situated even farther north, perhaps at the latitude of the British Columbia-Yukon Territory boundary. The meager data from the Quesnellia terrane suggest that this terrane probably lay latitudinally between the Stikine and Eastern Klamath terranes. At this time the eastern Tethyan terranes were located far out in the Paleopacific Ocean at relatively low latitudes. The rather abrupt cooling of the oceans beginning in the latter part of the Early Permian resulted in extinction of the colonial corals of the Cordilleran-Arctic-Uralian realm [Fedorowski et al., 2007] and extermination of fusulinids on the North American craton north of the latitude of Texas. After or during this cooling event at the end of the Early Permian, the terranes of the McCloud Belt and the composite Wrangellia-Alexander terrane moved about 15˚ southward relative to cratonal North America, so that part of the McCloud Belt (Quesnellia and Eastern Klamath terranes) lay at least as far south as the latitude of southern California or northern Baja California by the Middle Permian. While the McCloud Belt and the Wrangellia-Alexander terrane were moving southward and perhaps closer to cratonal North America, the Tethyan province apparently was expanding eastward, perhaps due to migration of some of the eastern Tethyan terranes closer

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to North America. This allowed a few members of that fauna to disperse into two terranes of the McCloud Belt (Eastern Klamath and Quesnellia) and onto the North American craton in Texas. Later all of the terranes were accreted to the North American craton and were smeared out along that margin with some blocks that bear warm-water faunas being carried to high latitudes. This is shown by the very widespread distribution of some fusulinid species. For instance, species of Parafusulina having gigantic microspheric forms occur in cratonal rocks in Texas, as well as well as in the McCloud Belt and some other non-Tethyan terranes, stretching from Coahuila and Sonora, Mexico through northern California, Washington, and British Columbia to Alaska [Stevens, 1995]. These fusulinids are distributed over about 50˚ of latitude (Fig. 4).

*

Alaska Yukon Territory

* British Columbia

* *

Alberta

* Copyright © 2009. Nova Science Publishers, Incorporated. All rights reserved.

* * WA OR

* **

*

MT ID WY

*

NV

CA

*

UT CO

*

Tethyan Fusulinids Giant Parafusulina

AZ NM USA Mex ico

500 km

Figure 4. Distribution of gigantic Parafusulina and eastern Tethyan faunas in western North America.

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Nature of Permian Faunas in Western North America

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The distribution of Middle and Late Permian fusulinids in the eastern Tethyan terranes parallels that of species of giant Parafusulina. Terranes and blocks containing the eastern Tethyan faunas extend from the Porterville area in the southern Sierra Nevada [Saleeby et al., 1978], to the central Sierra Nevada [Douglass, 1967], the western Klamath Mountains [Stevens et al., 1991], central Oregon [Bostwick and Nestell, 1967], western Washington [Bostwick and Nestell, 1967; Skinner and Wilde, 1966], the Cache Creek terrane in British Columbia [e.g., Monger, 1975; Ross and Ross, 1983], and finally to an area near Anchorage, Alaska [Stevens et al., 1997], representing a spread of more than 30˚ of latitude (Fig. 4).

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REFERENCES Beauchamp, B., and Desrochers, A. 1997. Permian warm- to very cold-water carbonates and cherts in northwestern Pangea, p. 327-347. In James, N.P., and Clark, J.A.D., eds. Soc. Sed. Geol. Special Publ. 56. Belasky, P. 1994. Biogeography of Permian corals and the determination of longitude in tectonic reconstructions of the Paleopacific region, p. 621-646. In Embry, A.F., Beauchamp, B., and Glass, D.J., Pangea: Global Environments and Resources. Canadian Soc. Petrol. Geol. Memoir 17. Belasky, P., and Runnegar, B. 1994. Permian longitudes of Wrangellia, Stikinia, and Eastern Klamath terranes based on coral biogeography. Geol., v. 22, p. 1095-1098. Belasky, P., and Stevens, C.H. 2006. Permian faunas of westernmost North America. Paleobiogeographic constraints on the Permian positions of Cordilleran terranes: in Haggart, J.W., Enkin, R.J., and Monger, J.W.H., eds. Paleogeography of the North American Cordillera: Evidence for and against large-scale displacements. Geol. Assoc. Canada Special Pap. 46, p. 71-80. Belasky, P., Stevens, C.H., and Hanger, R.A. 2002. Early Permian location of western North American terranes based on brachiopod, fusulinid, and coral biogeography. Palaeogeog., Palaeoclim., Palaeoecol., v. 179, p. 245-266. Bensh, F.R., Rauser-Chernousova, D.M., Bensh, F.R., Vdovenko, M.V., et al. 1996. Reference book on the systematics of Paleozoic foraminifera (Endothyroida, Fusulinoida). M.: Nauka, 207 p. (in Russian). Bostwick, D.A., and Nestell, M.K. 1967. Permian Tethyan fusulinid faunas of the northwestern United States, in Adams, C.G., and Ager, D.V., eds. Aspects of Tethyan Biogeography. System. Assoc. Publ. 7, p. 93-102. Butler, R.F., Gehrels, G.E., and Bazard, D.R. 1997. Paleomagnetism of Paleozoic strata of the Alexander terrane, southeastern Alaska. Bull. Geol. Soc. Amer., v. 109, p. 1372-1388. Cassity, P.E., and Langenheim, R.L. 1966. Pennsylvanian and Permian fusulinids of the Bird Spring Group from Arrow Canyon, Clark County, Nevada. Jour. Paleo., v. 40, p. 931968. Coogan, A.H. 1960. Stratigraphy and paleontology of the Permian Nosoni and Dekkas Formations (Bollibokka Group). Univ. Calif. Publ. Geol. Sci., v. 36, p. 243-316. Douglass, R.C. 1967. Permian Tethyan fusulinids from California. U.S. Geol. Surv. Professional Pap. 593-A, 13 p., 6 pls.

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Dunbar, C.O., and Skinner, J.W. 1937. The Geology of Texas, v. 3, pt. 2, Permian Fusulinidae of Texas. Texas Univ. Bull. 3701, p. 517-825 Fedorowski, J., Bamber, E.W., and Stevens, C.H. 2007. Lower Permian colonial rugose corals, western and northwestern Pangaea: Taxonomy and distribution. NRC Res. Press, Ottawa, Onterio, Canada, 231 p. Gardner, M.C., Bergman, S.C., Cushing, G.W., MacKevett, E.M., Jr., Plafker, G., Campbell, R.B., Dodds, C.J., McClelland, W.C., and Mueller, P.A. 1988. Pennsylvanian pluton stitching of Wrangellia and the Alexander terrane, Wrangell Mountains, Alaska. Geol., v. 16, p. 967-971. Harker, P., and Thorsteinsson, R. 1960. Permian rocks and faunas of the Grinnell Peninsula, Arctic Archipelago. Geol. Surv. Canada Mem. 309, p. 1-89. Howell, D.G., Schermer, E.R., Jones, D.L., Ben-Avraham, Z., and Scheibner, E. 1985. Preliminary tectonostratigraphic terrane map of the circum-Pacific region. Amer. Assoc. Petrol. Geol., Tulsa, Oklahoma. Irving, E., and Monger, J.W.H. 1987. Preliminary paleomagnetic results from the Permian Asitka Group, British Columbia. Canadian Jour. Earth Sci., v. 24, p. 1490-1497. Jin Yugan, Wardlaw, B.R., Glenister, B.F., and Kotlyar, G.V. 1997. Permian chronostratigraphic subdivisions : Episodes, Internat. Union Geol. Sci., v. 20, no. 1, p. 10-15. Jones, D.L., Silberling, N.J., and Hillhouse, J. 1977. Wrangellia-A displaced terrane in northwestern North America. Canadian Jour. Earth Sci., v. 14, p. 2565-2577. Kistler, R.W. 1978. Mesozoic paleogeography of California: A viewpoint from isotope geology, p. 75-84, in Howell, D.G., and McDougall, K.A., eds. Mesozoic Paleogeography of the Western United States, Pacific Coast Paleogeography Symposium 2. Pac. Sect. SEPM., Los Angeles. Knight, R.L. 1956. Permian fusulines from Nevada. Jour. Paleo., v. 30, p. 773-793. Leven, E. Ja. 1997. Permian stratigraphy and Fusulinida of Afghanistan with their paleogeographic and paleotectonic implications. Geol. Soc. Amer. Special Pap. 316, 134p. Magginetti, R.T., Stevens, C.H., and Stone, P. 1988. Early Permian fusulinids from the Owens Valley Group, east-central California. Geol. Soc. Amer. Special Pap. 217, 61p. Mankinen, E.A., and Irwin, W.P. 1990. Review of paleomagnetic data from the Klamath Mountains, Blue Mountains, and Sierra Nevada; Implications for paleogeographic reconstructions. Geol. Soc. Amer. Special Pap. 255, p. 397-409. Mankinen, E.A., Irwin, W.P., Gromme, C.S. 1989. Paleomagnetic study of the Eastern Klamath terrane, California, and implications for the tectonic history of the Klamath Mountains Province. Jour. Geophys. Res., v. 94, p. 10444-10472. Mankinen, E.A., Linsley-Griffin, N., and Griffin, J.R. 2002. Concordant paleolatitudes for Neoproterozoic ophiolitic rocks of the Trinity Complex, Klamath Mountains, California. Jour. Geophy. Res., v. 107, NO. B10, 2254, doi:10.1029/2001JB001623, 2002. Miller, M.M. 1987. Dispersed remnants of a northeast Pacific fringing arc: Upper Paleozoic terranes of Permian McCloud faunal affinity, western United States. Tectonics, v. 6, p. 807-830. Minato, M., and Kato, M. 1965. Waagenophyllidae: Jour. Fac. Sci., Hokkaido Univ., v. 12, p. 1-241.

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Monger, J.W.H. 1969. Stratigraphy and structure of the Upper Paleozoic rocks, northeast Dease Lake map area, British Columbia (104J): Geol. Surv. Canada Pap. 68-48, 41p. Monger, J.W.H. 1975. Upper Paleozoic rocks of the Atlin terrane, northwestern British Columbia and south-central Yukon. Geol. Surv. Canada Pap. 74-47, 63 p. Monger, J.W.H., and Ross, C.A. 1971. Distribution of fusulinaceans in the western Canadian Cordillera. Canadian Jour Earth Sci., v. 8, p. 259-278. Nassichuk, W.W., and Wilde, G.L. 1977. The Belcher Channel Formation at Blind Fiord, southwestern Ellesmere Island. Geol. Surv. Canada Bull. 268, 58p. Nelson, S.J., and Nelson, E.R. 1985. Allochthonous Permian micro- and macrofauna, Kamloops area, British Columbia. Canadian Jour. Earth Sci., v. 22, p. 442-451. Newton, C.R., 1988. Significance of ‘Tethyan’ fossils in the American Cordillera. Sci., v. 242, p. 285-391. Orchard, M.J., and Danner, W.R. 1991a. The paleontology of Quesnellia, p. 139-168, in Smith, P. L., ed. A field guide to the paleontology of southwestern Canada. The First Canadian Paleontology Conference, Univ. British Columbia, Vancouver, Canada. Orchard, M.J., and Danner, W.R. 1991b. The paleontology of the Cache Creek terrane, p. 169-188, in Smith, P.L., ed. A field guide to the paleontology of southwestern Canada. The First Canadian Paleontology Conference, Univ. British Columbia, Vancouver, Canada. Panuska, B.C., and Stone, D.B. 1985. Latitudinal motion of Wrangellia and Alexander terranes and the Southern Alaska Superterrane, p. 109-119, in, Howell, D.B., ed. Tectonostratigraphic Terranes of the Circum-Pacific Region. Circum-Pacific Council on Energy and Mineral Resources, Houston. Petocz, R.G. 1970. Biostratigraphy and Lower Permian Fusulinidae of the Upper Delta River area, east-central Alaska Range. Geol. Soc. Amer. Special Pap. 130, 94p. Pitcher, M.G. 1960. Fusulinids of the Cache Creek Group, Stikine River area, Cassiar District, British Columbia, Canada. Brigham Young Univ. Res. Stud., Geol. Ser., v. 7, 64p. Rich, M. 1961. Stratigraphic section and fusulinids of the Bird Spring Formation near Lee Canyon, Clark County, Nevada. Jour Paleo., v. 35, p. 1159-1180. Robinson, G.B., Jr. 1961. Stratigraphy and Leonardian fusulinid paleontology in central Pequop Mountains, Elko County, Nevada. Brigham Young Univ. Geol. Stud., v. 8, p. 93145. Ross, C.A. 1960. Fusulinids from the Hess Member of the Leonard Formation, Leonard Series (Permian), Glass Mountains, Texas: Contri. Cushman Found. Foram. Res., v. 11, p. 117-133. Ross, C.A. 1962. Fusulinids from the Leonard Formation (Permian), western Glass Mountains, Texas: Contri. Cushman Found. Foram. Res., v. 13, p. 1-21. Ross, C.A. 1963a. Standard Wolfcampian Series (Permian), Glass Mountains, Texas. Geol. Soc. Amer. Mem. 88, 205 p. Ross, C.A. 1963b. Fusuliniids from the Word Formation (Permian), Glass Mountains, Texas. Contri. Cushman Found. Foram. Res., v. 14, pt. 1, p. 17-31. Ross, C.A. 1967a. Development of fusulinid (Foraminiferida) faunal realms. Jour. Paleo., v. 41, p. 1341-1354. Ross, C.A. 1967b. Late Paleozoic Fusulinacea from northern Yukon Territory. Jour. Paleo., v. 41, p. 709-725.

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Ross, C.A. 1978. Permian fusulinaceans from the St. Elias Mountains, Yukon Territory. Contri. Canadian Paleo., Geol. Surv. Canada Bull. 267, p. 65-75. Ross, C.A. and Bamber, E.W. 1978. Middle Carboniferous and Early Permian fusulinaceans from the Monkman Pass area, northeastern British Columbia. Contri. Canadian Paleo., Geol. Surv. Canada Bull. 267, p.25-41. Ross, C.A., and Monger, J.W.H. 1978. Carboniferous and Permian fusulinaceans from the Omineca Mountains, British Columbia. Contri. Canadian Paleo., Geol. Surv. Canada Bull. 267, p. 43-63. Ross, C.A., and Ross, J.R.P. 1983. Late Paleozoic accreted terranes of western North America, p. 7-22, in Stevens, C.H., ed. Pre-Jurassic Rocks in Western North American Suspect Terranes. Pac. Sect SEPM, Los Angeles. Ross, C.A., and Ross, J.R.P. 2003. Fusulinid sequence evolution and sequence extinction in Wolfcampian and Leonardian Series (Lower Permian), Glass Mountains, West Texas. Rivista Italiana Paleo. Stratig., v. 109, p. 281-306. Ross, C.A., and Tyrell, W.W., Jr. 1965. Pennsylvanian and Permian fusulinids from the Whetstone Mountains, southeast Arizona. Jour. Paleo., v. 39, p. 615-635. Rui, L., Nassichuk, W.W., and Thorsteinsson, R. 1994. The Lower Permian Fusulinacean Sphaeroschwagerina in the Sverdrup Basin, Canadian Arctic Archipelago. Pangea. Global Environments and Resources. Canadian Soc. Petrol. Geol. Mem. 17, p. 891-905. Sabins, F.F., Jr., and Ross, C.A. 1963. Late Pennsylvanian Early Permian fusulinids from southeast Arizona. Jour. Paleo., v. 37, p. 323-365. Saleeby, J.B., Goodin, S.E., Sharp, W.D., and Busby, C.J. 1978. Early Mesozoic paleotectonic-paleogeographic reconstruction of the southern Sierra Nevada region, p. 311-336, in Howell, D.G., and McDougall, K.A., eds. Mesozoic Paleogeography of the Western United States, Pacific Coast Paleogeography Symposium 2. Pac. Sect. SEPM., Los Angeles. Scotese, C.R., and Langford, R.P. 1995. Pangea and the paleogeography of the Permian, p. 319, in Scholle, P.A., Peryt, T.M., Ulmer-Scholle, D.S., eds. The Permian of Northern Pangea, v. 1: Paleogeography, Paleoclimates, Stratigraphy, Springer-Verlag, Berlin. Scotese, C.R., and McKerrow, W.S. 1990. Revised world maps and introduction, p. 1-21, in McKerrow, W.S., and Scotese, C.R., eds. Palaeozoic Palaeogeography and Biogeography. Geol. Soc. Mem. 12, London. Skinner, J.W., and Wilde, G.L. 1965. Permian biostratigraphy and fusulinid faunas of the Shasta Lake area, northern California. Univ. Kansas Paleo. Contri., Protozoa, Art. 6, 98p. Skinner, J.W., and Wilde, G.L. 1966. Permian fusulinids from Pacific Northwest and Alaska. Univ. Kansas Paleo. Contri., Pap. 4, 64 p. 49 pls. Slade, M.L. 1961. Pennsylvanian and Permian fusulinids of the Ferguson Mountain area Elko County, Nevada. Brigham Young Univ. Geol. Stud., v. 8, p. 55-92, 2 pls. Stevens, C.H. 1995. A giant Permian fusulinid from east-central Alaska with comparisons of all giant fusulinids in western North America. Jour. Paleo., v. 69, p. 805-812. Stevens, C.H. 2008a. Permian colonial rugose corals from the Wrangellian terrane in Alaska. Jour. Paleo., v. 82, p. 1043-1050. Stevens, C.H. 2008b. Fasciculate rugose corals from Gzhelian and Lower Permian strata, Pequop Mountains, northeast Nevada: Jour. Paleo., v. 82. p. 1190-1200. Stevens, C.H., and Rycerski, B. 1983. Permian colonial rugose corals in the western Americas – Aids in positioning of suspect terranes, p. 23-365, in Stevens, C.H., ed. Pre-

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Jurassic Rocks in Western North American Suspect Terranes. Pac. Sect. SEPM, Los Angeles. Stevens, C.H., and Stone, P. 2007. The Pennsylvanian-Early Permian Bird Spring carbonate shelf, southeastern California: Fusulinid biostratigraphy, paleogeographic evolution, and tectonic implications. Geol. Soc. Amer. Special Pap. 429, 82 p. Stevens, C.H., and Stone, P. 2009a. New Permian fusulinids from Conglomerate Mesa, southeastern Inyo Mountains, east-central California. Jour. Paleo., v. 83, p. 9-29. Stevens, C.H., and Stone, P. 2009b. New fusulinids from Lower Permian turbidites at Conglomerate Mesa, southeastern Inyo Mountains, east-central California. Jour. Paleo., v. 83, p. 395-400. Stevens, C.H., Davydov, V.I., and Bradley, D. 1997. Permian Tethyan Fusulinina from the Kenai Peninsula, Alaska. Jour. Paleo., v. 71, p. 985-994 Stevens, C.H., Luken, M.D., and Nestell, M.K. 1991. The Upper Permian fusulinids Reichelina and Parareichelina in northern California: Evidence for long-distance tectonic transport, p. 635-642, in Cooper, J.E., and Stevens, C.H., eds. Paleozoic Paleogeography of the Western United States II. Pac. Sect. SEPM, v. 67, Los Angeles. Stevens, C.H., Miller, M.M., and Nestell, M. 1987. A new Permian waagenophyllid coral from the Klamath Mountains, California. Jour. Paleo., v. 61, p. 691-699. Stevens, C.H., Stone, P., and Kistler, R.W. 1992. A speculative reconstruction of the middle Paleozoic continental margin of southwestern North America. Tectonics, v. 11, p. 405419. Stevens, C.H., Stone, P., and Ritter, S.M. 2001. Conodont and fusulinid biostratigraphy and history of the Pennsylvanian to Lower Permian Keeler Basin, east-central California. Brigham Young Univ. Geol. Stud., v. 46, p. 99-142. Stevens, C.H., Wagner, D.B., and Sumsion, R.S. 1979. Permian fusulinid biostratigraphy, central Cordilleran Miogeosyncline. Jour. Paleo., v. 53, p. 29-36. Stevens, C.H., Yancey, T.E., and Hanger, R.A. 1990. Significance of the provincial signature of Early Permian faunas of the eastern Klamath terrane, p. 201-218, in Harwood, D.S., and Miller, M.M., eds. Paleozoic and early Mesozoic paleogeographic relations; Sierra Nevada, Klamath Mountains and related terranes. Geol. Soc. Amer. Special Pap. 255. Wardlaw, B.R. 1980. Middle-Late Permian paleogeography of Idaho, Montana, Nevada, Utah, and Wyoming, p. 353-361, in Fouch, T.D., and Magathan, E.R., eds. Paleozoic Paleogeography of the west-central United States. Rocky Mountain Paleogeography Symposium 1. Rocky Mt. Sect. SEPM, Denver. Wilde, G.L. 2006. Pennsylvanian-Permian fusulinaceans of the Big Hatchet Mountains, New Mexico. New Mexico Mus. Nat. Hist. Sci. Bull 38, 331 p. Wilde, G.L., and Rudine, S.F. 2000. Late Guadalupian biostratigraphy and fusulinid faunas, Altuda Formation, Brewster County, Texas, p. 343-371, in Wardlaw, B.R., Grant, R.E., and Rohr, D.M., eds. The Guadalupian Symposium. Smithsonian Contri. Earth Sci., no. 32. Williams, T.E. 1963. Fusulinidae of the Hueco Group (Lower Permian), Hueco Mountains, Texas. Peabody Mus. Nat. Hist., Yale Univ. Bull. 18, 123p. Williams, T.E. 1966. Permian Fusulinidae of the Franklin Mountains, New Mexico-Texas. Jour. Paleo., v. 40, p. 1142-1156. Yang, Z., and Yancey, T.E. 2000. Fusulinid biostratigraphy and paleontology of the Middle Permian (Guadalupian) strata in the Glass Mountains and Del Norte Mountains, West

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Calvin H. Stevens and Paul Belasky

Texas, p.185-257, in Wardlaw, B.R., Grant, R.E., and Rohr, D.M., eds. The Guadalupian Symposium, Smithsonian Contri. Earth Sci., no. 32. Ziegler, A.M., Hulver, M.L., Rowley, D.B., 1996, Permian world topography and climate, p. 60-72, in Martini, I.P., ed., Late glacial and postglacial environmental changes – Quaternary, Carboniferous, Permian, and Proterozoic. Oxford University Press, New York.

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Art work by Bridget Wyatt. Reviewed by Paul Stone and David W Andersen.

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In: Geomorphology and Plate Tectonics Editors: D. M. Ferrari, A. R. Guiseppi

ISBN: 978-1-60741-003-4 © 2009 Nova Science Publishers, Inc.

Chapter 11

GEODYNAMIC EVOLUTION OF THE NORTH AFRICAN ATLASIC BELT Missoum Herkat * Faculté des Sciences de la Terre, Université des Sciences et de la Technologie, El Alia, Algiers, Algeria

ABSTRACT

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The North African atlasic belt, including the High Atlas, the Saharan Atlas, the Aurès-Tunisian segment and their Preatlasic zones, is located at the boundary of the North Africa and Sahara domains. This elongated chain, starting from the Morocco Atlas, near the Atlantic Ocean and extending farther eastward as far as the Tunisian Atlas fringing the Mediterranean Sea has experienced a polyhistoric evolution. Rifting and opening of the basins occurred during the Triassic and Jurassic times and are succeeded by a recovery of the synsedimentary tectonics during the Cretaceous, generating tilting of blocks and new subsidence episodes. Palaeogene and Neogene times registered alternating folding and sedimentary filling. The paleogeography of the Atlasic Basins changed significantly during their history. After the development of subsiding troughs filled with terrigenous and evaporitic sediments during the Triassic period, the Lias platforms spread over the entire Maghrebian domain and were followed, during the Middle Jurassic times, by terrigenous marine and deltaic deposits. Shallow marine carbonate and terrigenous platforms developed gradually during the Late Jurassic. The early Cretaceous was a period of widespread continental to coastal marine siliciclastic sedimentation supplied from the southernmost old African shields. The Late Cretaceous registered mainly carbonate deposits lasting to the Middle Palaeogene. The main folding phase occurred during the Middle Eocene. Postcollisional sedimentary basins formed during the Neogene in eastern Algeria and Tunisia, when western Algeria and Morocco were definitively emerged. The geodynamic evolution of the Atlasic chain, located between the Atlantic Ocean and the Eastern Mediterranean Basin on its margins and northwards bordered by the Maghrebian (Alpine) Ocean, is influenced by every one of these oceans. Like this, during *

Correspondence to: Faculté des Sciences de la Terre, Université des Sciences et de la Technologie, B.P. 32 16111 El Alia, Algiers, Algeria.

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the Triassic and Jurassic times the rifting of the Atlasic Basins is related to the Atlantic and Maghrebian-Liguride Ocean opening, when, during the Cretaceous period, the rejuvenated extensional tectonics is correlated to that of the Neotethys south-margin.

Key words: North Africa; Atlasic Domain; Tectonics; Sedimentation; Subsidence.

INTRODUCTION Main Geological Features

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The aim of this study is to examine the relationships between the structural pattern and the sedimentation features that are indicative of the geodynamic evolution of the Atlasic basins of North Africa since the Triassic period, stressing particularly the Mesozoic times. The north-African Atlas is an E–W to ENE–WSW trending belt intermediary between the Alpine belt and the Saharan craton (Fig.1), including the High Atlas in Morocco, which branches the Middle Atlas SW–NE trending, the Saharan Atlas and Aurès Mounts in Algeria and the Tunisian Atlas in Tunisia (Fig. 2). It extends about an area 2000 km long and 100 km wide. The north-African belt separates the Saharan Platform from the Meseta-Preatlasic zone which lies at the front of the Tell-Rif Alpine domain, located northward. The Tell of Algeria and the Rif in Morocco are parts of the Maghrebides, a chain extending from the northern margin of North Africa to Sicily, which is a part of the Alpine belt. The Tell is constituted by south-verging thrust sheets.

Figure 1. Africa geological map (After Guiraud, 1998, modified). 1: Archean, 2: Proterozoic, 3: Alpine belt and its foreland, 4: Phanerozoic, 5: Faults, 6: Mesozoic and Cenozoic rifts, 7: Alpine thrust front.

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Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers, Incorporated, 2009.

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Figure 2. Maghreb Main Structural Domains. In grey: Atlasic basins. 1: Meseta, High Plateaus and Preatlasic zone, 2: Allochtonous, 3: Precambrian basement: Precambrian high zones: A: Western High Atlas, B: Béchar, C: Laghouat, D: Zibans, E: North- south axis.4: Tunisian Eastern Platform. 5. Main limits of the geological domains, 6: Faults, 7: Presumed faults, 8: Western limit of the tectonic extension during the Aptian (I), Latest Albian (II) and Latest Cenomanian (III) periods.

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Figure 3. Palinspatic map of the Eastern Atlasic Domain during the Late Cretaceous and palinspatic section in the Oulad Nail Basin. (a) 1: Platforms, 2: Ramp, 3: Transition Ramp - Basin 4: Offshore Platforms, 5: Basin, 6: Allochtonous limit, 7: Faults, 8: Presumed faults. (b) Palinspatic section of the Oulad Nail Basin at the end of the Cretaceous period. NAF: North Atlasic Fault, SAF: South Atlasic fault. (c) Palinspatic section of the Aurès and Mellègue basins at the end of the Cretaceous period. HGF: Hamimat Guerra Fault, Tébessa - Kasserine Fault, OKDF: Ouenza - Kalaa Djerda Fault.

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The Atlasic domain comprises the Atlas chain and the Preatlasic zone located in the front of this chain (Fig. 2). The Atlasic chain is composed of different segments from Morocco to Tunisia: -

The High Atlas which passes north-easternward to the Middle Atlas and northernward to the Hercynian Moroccan Meseta, The Saharan Atlas including western (Ksour Mountains), central (Djebel Amour) and eastern (Oulad Nail Mountains and Zibans) parts is prolonged by the Aurès Mounts which continue northeast-wards with the Tunisian Atlas (Fig. 3). The Aurès Mountains pass northward to the Mellègue Mountains prolonged with the Tunisian “Diapir zone”, corresponding to the Preatlasic zone. This zone is bordered northward by the parautochtonous - autochtonous of Medjerda Mounts extending from Algeria to Tunisia, called also in its Tunisian part “Tunisian Through”. The Medjerda parautochtonous-autochtonous constitutes a zone of transition between the Preatlasic zone and the Alpine Tellian Through.

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High and Middle Atlas The Atlasic chain in Morocco comprises the High Atlas and the Middle Atlas. The High Atlas, passing northward to the Meseta Hercynian high zone, comprises from west to east four parts according to Michard, (1976): - The Seaboard western High Atlas, corresponding to a sedimentary basin, named the Agadir-Essaouira Basin, on the Atlantic Ocean margin, comprises a sedimentary pile including a thick Triassic succession overlain by a Jurassic and Cretaceous-Eocene series intruded by Triassic diapirs. - The High Atlas of Marrakech which is a chain constituted by a Panafrican and Palaeozoic basement, locally overlain by a Permian to Triassic cover. - The Central High Atlas showing a thick sedimentary pile including the Triassic, the Jurassic and the Cretaceous series. - The Eastern High Atlas is constituted by the same sedimentary cover but less subsident. The High Atlas of Marrakech shows a sedimentary pile identical to that of the Central and Eastern High Atlas, nevertheless with much more Tertiary deposits (Feddan, 1999; Charrière, 1990). The basements of the High Atlas and of the Meseta are essentially formed by Hercynian rocks, locally lying on a Panafrican basement. The faults observed in the Palaeozoic of the High Atlas are NNW-SSE trending. In the Meseta, the faults are ENE-WSW and ESE-WNW trending. Two representations have been proposed for the Atlas Trough origin: -

A strike-slip fault system inducing the formation of pull-apart basins between the bordering Mesetan and Saharan shields (Mattauer et al. 1977; Laville, 1985; Feddan, 1989). The stress field during the Triassic and Jurassic basin-opening episodes was

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-

characterized by NW–SE tension, developing NE-SW normal faults (Mattauer et al., 1977). A basin corresponding to an extensional rift characterized by the existence of a central horst (Warm, 1988) and a north-verging detachment fault.

The main rifting phase occurred during the Late Triassic-Early Lias involving the development of continental rift basins filled with clastics (Beauchamp, 1983). The development of a narrow subsiding basin occurred during the Pliensbachian-early Toarcian (Warm, 1988) or during the Sinemurian according to Canérot et al. (2003). This basin was joined with the Atlantic Ocean and with the Tethyan Ocean towards the NE. The rift of the High Atlas aborted after these extensional phases. Subsequent to this period, the basin received, essentially continental deposits, with the exception of transgressive carbonate beds deposited during the Cenomanian and Turonian period. Two causes can be envisaged for the end of the subsidence in this basin. The first is an early compressive phase (Choubert and Faure-Muret, 1962; Piqué et al., 2002). Some tectonic features, as intraformational truncations from the synclines to the anticlines and the existence of progressive unconformities in the limbs of the anticlines, are in favour of synsedimentary uplift or early folding. In the anticlines, the core of which is occupied by magmatic rocks, the uplift could be due to the ascending magma (Arboleya et al., 2004). The age of this first phase of folding is supposed to occur during the Middle to Late Jurassic period. However, the geometric relationships in some structures suggest rather extensional processes (Arboleya et al., 2004); therefore unconformities observed within Dogger marine beds, instead could be due to distension episodes. Latest Cretaceous beds show local evidence of growth folding, suggesting the occurrence of an early compression phase according to Laville et al., (1977) and Amrhar (1995). This first compressional event could correspond to the Santonian phase which is the first significant tectonic episode registered in Africa during the Cretaceous period (Guiraud and Bosworth, 1997). This phase correlates with a high-pressure metamorphic event in the western Mediterranean region related to the convergence of the Iberian microplate with Africa (Reicherter et al., 2000). The second cause which could explain the absence of renewed subsidence after the Dogger is that anyone tectonic extension has affected the High Atlas after this period; indeed, the Late Jurassic rifting episode and all the subsequent phases of extension known in other parts of the Atlas belt were not registered in the High Atlas and did not permit to the sedimentary basins to keep a marine sedimentation after the Bajocian period. The main phases of deformation in the High Atlas were post-Cretaceous, probably during the Neogene, after Piqué et al., (2002).

Saharan Atlas and Aurès Mounts The main geological studies concerning the Preatlasic zone, Northeast Saharan Atlas, and Aurès basins are those of Laffitte (1939), Dubourdieu (1956), Emberger (1960), Guiraud (1990), Vila (1980), Bureau (1986), Kazi Tani (1986), and Herkat (1999).

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Figure 4. Palaeostructural map of the eastern Atlasic Domain basins on Late Cenomanian to Early Turonian. Localities: Symbols caption: 1: Unconformity, 2: Normal fault dip, 3: Inverse fault dip, 4:

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Dextral strike-slip fault, 5: Sinistral strike-slip fault, 6: High trend axis, 7: Subsident axis, 8: Triassic Diapirism, 9: Seismites, 10: Extension, 11: Allochtonous.

The basement is not visible in the Saharan and Aurès Atlas and forms scarce outcrops only in the Preatlasic zone. Its presence in the Atlasic chain is attested by the varied rocks wrapped up in the Triassic diapirs, including magmatic rocks. The fault system of the basement exerted a pronounced influence on the history of the Mesozoic basins (Fig. 4). It is overlain by a thick Triassic salt pile which constituted a major disharmony level and controlled the pattern of the syndepositional structuring and folding. The aeromagnetic basement contours show in the Aurès and eastern Atlas several directions of the faults (Herkat, 1999; Herkat and Guiraud, 2006) (Fig. 4): -

-

NNE-SSW and NW-SE trending faults are probably Hercynian as in the High Atlas. NE-SW trending faults could be also deep-sealed in the Hercynian basement and were reactivated during the Jurassic time; however some of them were juvenile, formed by the Jurassic extension. E-W trending faults are observable in some parts of the Atlasic belt, particularly the Central Saharan Atlas. N-S trending faults are generally visible in the south margin of the Saharan Atlas.

This fault pattern was successively reactivated as extensional or transtensive system, during the basin filling period (Triassic to Cretaceous) and as compressional or transpressive system when the main folding occurred (Cenozoic). According to the azimuth of the faults relatively to the maximum stresses during each phase, they were activated either as normal or reverse faults or dextral or sinistral strike-slips.

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Tunisian Atlas The Tunisian Atlas is the main geological domain of Tunisia. It is composed of the northern, central and southern parts. The Northern Atlas is characterized by tilted blocks bounded by NW-SE trending deepsealed faults active during the Cretaceous to Tertiary period. They are from north to south, the Kalaa Djerda, Sbiba, Kasserine and Gafsa faults. Numerous extrusions of the Triassic lay in the northern part of this domain. The typical composition of the facies during the Cretaceous is basinal. The Central Atlas comprised between the Gafsa and the Kasserine faults is NW-SE trending and corresponds during the Cretaceous to a wide Platform forming a structural high which emerged during the Senonian, probably as a result of a compressive phase. The Southern Atlas is marked by an important paleogeographic feature during the Cretaceous, the Gafsa Basin. The structural pattern is characterized also by strike-slip faults, N180° trending in the vicinity of the North-south axis, N60° trending in the Northern Atlas and N90° trending in the Central Atlas (Burollet, 1956, Ben Ayed, 1986; Zargouni, 1985; Boukadi, 1994; Bedir, 1995; Zouaghi et al., 2005). These essentially inherited faults have caused the structuring of the basins and subbasins which were also strongly influenced by the Triassic salt intrusions that accentuated the depocenters and elevations (Zouaghi et al., 2005).

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STRUCTURAL TRENDS IN THE ATLASIC BELT AND AFRICAN CRATON The main structural controls on the organization of the Atlasic belt and its geodynamic evolution are exerted by the fault systems which belong to the Hercynian basement and the Precambrian of the Saharan craton. These trends correspond to a network of deep-rooted faults rarely showed in surface geological maps, most frequently recognized by subsurface methods, aeromagnetic or gravimetric basement depth contours. The main structural trends are North-south and E-W directed:

North-South Trends The Atlasic belt is segmented in several parts from Morocco to Tunisia, bounded by North-south fault trends marking megashear zones (Caby, 1970), rooted in the Precambrian basement, constituting an important structural feature of the old Tuareg and West African shields (Fig. 1 and 2). From west to east they are:

Béchar Suture This complex zone corresponds to the transition between the High Atlas and the Saharan Atlas. It is marked by NNE-SSE trending faults (Bou Arfa) in the Atlasic chain and a brusque change in the direction of this chain from NE-SW in the Saharan Atlas to ESE-WNW in the High Atlas. In the Saharan domain, the Ougarta Hercynian chain is NW-SE striking and

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passes westward to the Anti-Atlas Hercynian chain in Morocco, ENE-WSW trending. The western termination of the Ougarta Mountains shows NNE trending faults.

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Laghouat Trend The North-south axis of Laghouat prolongs the North-south trending Mzab high structural zone which prolongs one of the main Precambrian fault zones of the Hoggar, the Idjerane Axis. It is expressed in the sedimentary cover by NS folds, faults in the western part of the Oulad Nail Basin (well visible in the Charef region) and the gravity data (Idres and Aifa, 1995). The Laghouat trend is marked by the change from the Djebel Amour Mountains to the Oulad Nail mountains which correspond to different basins; the first (Laghouat Basin) is characterized by EW and NE-SW inherited faults and the second (Oulad Nail Basin) shows essentially NW-SE and NE-SW faults. Furthermore, the tectonic extension did not proceed with a same pattern in these two domains, the Djebel Amour Basin corresponding rather to a symmetrical graben, when the Oulad Nail Basin shows a half-graben structure with tilted blocks (Fig. 3). The tectonic inversion is also different, resulting in “en-echelon” folds in the Oulad Nail Basin and in parallel conical folds in the Djebel Amour Basin. This difference is due essentially to the presence of deep-sealed NW-SE faults in the Oulad Nail and Aurès basins which were reactivated as wrench faults by the NW-SE directed maximum stress during the Eocene phase and induced the formation of “en-echelon” folds. Their absence in the Djebel Amour Basin produced mainly parallel folds taking the form of the NE-SW trending basement blocks. Zibans High Zone The Zibans High zone is a large promontory of the Saharan basement within the Saharan Atlas which is shown by aeromagnetic maps (Asfirane, 1995) and delimitated by NS faults. This High zone is in the prolongation of an important fault zone of the Precambrian in the Hoggar, the Amguid axis. The EW trending Zibans High zone exerted a permanent influence on the paleogeographic history of the domain separating the Oulad Nail Mountains from the Aurès Mountains. This zone evolved as a high zone, more stable than the other domains of the Atlasic chain, on which extended carbonate platforms, slightly subsiding during the Jurassic and Cretaceous periods; The Zibans high shows also an EW to ENE-WSW direction of the folds, different from the NE-SW orientation of the Aurès and Oulad Nail Mountains folds. Tébessa Trend Situated between the Aurès Mountains and the Tunisian Atlas, the Tébessa region shows particularly abrupt bends northernward of the fold orientation, marking the influence of a deep-sealed fault oriented NNE-SSW. Its position is at the western limit of the Kasserine mole in the Central Tunisian Atlas, bounded on its eastern margin by the Tunisian Northsouth axis, which constituted during the Cretaceous times an elevated zone and registered uplift during the Senonian. Tunisian North-South Axis The North-south axis is the main structural feature of Tunisia, marked by folds and faults north-south trending, which crosses the country from the south to the Mediterranean coast.

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This trend is generally related to the Precambrian basement (Burollet, 1956) and its influence was considerable in the geologic history of Tunisia. This axis separates the folded Atlasic domain westward from the Tunisian stable Eastern Platform eastward belonging to the Pelagian block.

East-West to ENE to ESE Trends The African Plate is cross-cut by east-west trending lineaments witch correspond to megashear zones affecting the Precambrian old shields (Guiraud et al., 1987) and include from the north to the south (Fig. 1): -

-

The North African shear zone corresponds to the ENE-WSW to WNW-ESE trending north and south Atlasic faults. These deep sealed faults were active during the Mesozoic to Cenozoic evolution of the Atlasic belt. Their movement was sinistral transtensional during the Triassic to early Cretaceous period and sinistral to dextral transtensional or transpressional since the Aptian to Tertiary times. The Guinea-Nubian shear zone ENE-WSW trending passes northwards the Guinean shield and southwards the Tuareg shield (Hoggar). The Central African shear zone ENE-WSW trending crosses the Benue Trough and extends eastwards to the south margin of the Red Sea.

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These main shear zones controlled the development of numerous rifts in Central Africa during the Cretaceous and the emplacement of magmatic activity (Guiraud and Bosworth, 1999).

PALEOGEOGRAPHIC AND PALEOTECTONIC EVOLUTION OF THE ATLASIC BASINS Five phases of evolution are distinguished: -

Triassic to early Jurassic rifting Middle to Late Jurassic rifting Cretaceous extensional episodes Senonian compressional events Paleogene folding.

Triassic- Lias Rifting The opening of the Atlasic basin is contemporaneous to the rifting of the Central Atlantic located on its west margin. Plate tectonic processes caused a reactivation of an inherited panAfrican and Hercynian fault system and resulted in the development of an EW to NE-SW trending oblique-slip rift zone, during the Late Triassic (Beauchamp, 1983). This basin

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received essentially continental sediments and volcanic flows. Several offshore and onshore basins initiated on the west part of Morocco at the same time, including the Agadir-Essaouira Basin which constitutes the western sea-board continuation of the High Atlas, experiencing an active subsidence and deposit of a thick siliciclastic and evaporitic sedimentary pile during the Mesozoic and Cenozoic period. In the Agadir basin on the Atlantic Margin, an extensional episode is marked by an accelerated subsidence (Fig. 5) during the Late Triassic early Lias period (Bouatmani et al., 2007).

Figure 5. Subsidence curves in the Essaouira Basin and Saharan Atlas. 1: Late Triassic and Early Jurassic phase, 2: Bajocian phase, 3: Late Jurassic phase, 3: Aptian, 4: Latest Albian phase, 5: Latest Cenomanian phase. Essaouira subsidence curve is after Bouatmani et al. (2007), modified.

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The Saharan Atlasic basin was bordered by NE-SW trending flexures and faults separating it from the Saharan platform and the Preatlasic high zone. The Triassic series, observed in diapirs, showing evaporitic facies and volcanic flow rocks, suggests an initiation of the tectonic extension in the axial zones of the basin prefiguring the future Atlasic Basin. Tilted blocks geometry, emersion and erosion of the block apices and thickness variations in the Upper Lias beds (Bourezg, 1984; Ait Ouali, 1991; Ait Ouali and Delfaud, 1995) and early Triassic salt halokinesis, highlighted by salt ridges observed in seismic lines (Bracene, 2001; Bracene et al., 2003), are consistent with a NW-SE directed tectonic extension during this period. In the Preatlasic zone, the Triassic series is characterized also by the presence of interbedded basic volcanic flows in the carbonate and conglomeratic deposits attesting of a large scale-extension since the Late Triassic period according to Elmi et al., (1982). This tectonic extension increased during the Lias characterized by a tilted blocks geometry and carbonate deposits. In Southern Tunisia the Triassic marine deposits were deposited in basins controlled by E-W normal faults and flexures (Bouaziz, 1995; Piqué and Laville, 1996). In summary, the Late Triassic and early Lias period were marked by an extensional tectonics affecting the whole atlasic belt from Morocco to Tunisia.

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Middle to Late Jurassic Rifting During the Jurassic times, two phases of extension occurred, the first limited geographically, happened through the Bajocian and the second, more spread in the Atlasic Domain, during the Kimmeridgian - Portlandian. The Bajocian was marked by a block-tilting which can be observed in the Central High Atlas (Canérot et al., 2003). An accelerated subsidence is also registered in the Western and Central Saharan Atlas (Fig. 5). In all the other parts of the Saharan Atlas and Aurès-Tunisian through, the Dogger does not outcrop. In the Atlantic coastal basins (Agadir) this phase is not observed (Fig. 5). A Late Jurassic extension phase occurred in the Central and Eastern Saharan Atlas as well as an early halokinesis of the Triassic salts. This tectonic extension is highlighted by an accelerated subsidence during the Late Kimmeridgian to early Tithonian (Fig. 5). In the Oulad Nail Basin, the seismic lines show evidence of a tilting of blocks along the NW/SE faults (Fig. 3b) (Herkat, 1999). This synsedimentary faulting attested by a thickening of the Kimmeridgian to Tithonian series in the tilted blocks suggests a tectonic extension episode reactivating the NE/SW trending faults. This tensional movement allowed the early halokinesis of the Triassic salts observed at the junction of the NE-SW and N-S trending faults revealed by the thinning of the Kimmeridgian and Tithonian series towards the diapirs and the reworking of Triassic rocks in the Late Tithonian series (Herkat, 1982, 1992). In the Central Atlasic Basin, pronounced variation of facies, between the opposed compartments of NE-SW trending faults is observed in the Djebel Zerga (Herkat, 1982). On the northern side of these faults, reefy facies indicate synsedimentary uplift, when their absence on the southern side marks a marine deepening, corresponding to a hanging wall block. These features are in favour of a syndepositional vertical throw of these faults which could be due to their extensional movement during the Late Kimmeridgian - Tithonian period.

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Figure 6. Subsidence curves in the Aurès and Tunisia basins. 1: Late Triassic and Early Jurassic phase, 2: Bajocian phase, 3: Late Jurassic phase, 3: Aptian, 4: Latest Albian phase, 5: Latest Cenomanian phase. Tunisia subsidence curves are after Burollet and Ellouz (1986), modified.

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Progressive unconformities are reported in the Upper Kimmeridgian of Laghouat region (Abed, 1982), attesting of syndepositional tectonic movements during this period. The observed accelerated subsidence indicates also a tectonic extension episode (Fig. 5). In Aurès Basin, the accelerated subsidence observed (Fig. 6) in the Upper Kimmeridgian to Portlandian series is in favour of the same extension episode as in the eastern Atlas. In central Tunisia early halokinesis extrusions of the Triassic salts are identified in the Jurassic series (Bédir, 1995), which suggest also a tectonic extension during this period. In the Agadir basin, an extensional episode is highlighted by an accelerated subsidence (Fig. 5) during the Oxfordian to Berriasian period and is accompanied by an important halokinesis of the Triassic salts (Bouatmani et al., 2007). The tectonic extension occurring during the Middle to Late Jurassic in a large part of the Atlasic belt is characterized by a NW-SE trending direction of the minimum stress. The vector motion of the African plate drift, NW-SE to WNW-ESE directed (Fig. 7) according to the cinematic models (Dewey et al., 1989, Rosenbaum et al., 2002), is parallel with this direction of the tectonic extension prevailing from the Triassic to the end of the Barremian times. The Middle Jurassic extension phase was registered only eastward the North - south trend of Laghouat region (Central Atlas), in the Western and Central Saharan Atlas and in the High Atlas. The Late Jurassic extensional phase was registered in the Saharan Atlas and Tunisian basins (Table 1). Northernward, in the Central Tellian zone which is a part of the Maghrebian - Liguride Alpine Ocean, ophiolites were found in the Middle to Upper Jurassic series (Bouillin and Kornprobst, 1974), denoting an accelerated extension during this period correlating with the Atlasic extensional phase. Westward of the Laghouat trend, in the Djebel Amour, the Ksour Basins and the Moroccan Atlasic basins, the NE-SW trending faults were not reactivated. Since the Dogger, these regions have been infilled by continental to shallowmarine deposits and registered a slowed subsidence (Elmi, 1978; Abed, 1982; Herkat, 1982).

Figure 7. Relative motions of Africa, Iberia and Europe during the Mesozoic and Cenozoic times (After Rosenbaum et al., 2002; Modified).

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Table 1. Synthetic table of the main tectonic and magmatic events in the basins of the North-African Atlasic belt during the Mesozoic and Cenozoic period.

Legend: 1: Extension, 2: Compression, 3: Magmatism, 4: Vector motion of Africa, 5: Gap. (A): Lateral augmentation of the number of tectonic extension phases during the Jurassic period, (B): Lateral propagation of the tectonic extension phases during the Cretaceous period. Absolute ages according to the time scale of Gradstein et al. (1995).

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Cretaceous Extensional Episodes (Aptian to Early Turonian) Early Aptian Rifting Episode A new rifting episode initiated at the beginning of the Early Aptian period in the northern part of the Auresian Basin (Mellègue Mounts). This distension phase was marked by a tilting of blocks towards the southwest in the NW-SE trending Tébessa trench resulting in a pronounced angular unconformity of the Aptian upon the Barremian beds, visible in the seismic lines (Herkat, 1999). This tectonic extensional episode affected also all the NW-SE trending trenches in this region (as the Ouenza trench) and was accompanied by an early halokinesis and extrusion of the Triassic salts in several anticline zones of the Mellègue Mountains (Masse and Thieuloy, 1979). Aptian rudist formations were deposited on these uplifted zones corresponding to the future anticline cores. According to Perthuisot and Rouvier (1990), the Triassic halokinesis could have already been initiated in this region during the Late Jurassic period, following the reactivation of NE-SW trending faults by an extensional episode. Others regions of the Algerian Atlasic Domain did not register this extension episode which seems restricted to the easternmost parts of North-Africa. In the Tunisian Through (Martinez et al., 1987), Central Tunisia (Mrabet, 1981; Chihi, 1995, Ouali, 1984), Eastern Tunisia (Haller, 1983; Turki, 1985) and Tunisian Sahel (Boukadi and Bedir, 1996) a tilting of blocks occurred during the Aptian times, marked by and accelerated subsidence (Fig. 6) and the reactivation of the N120° to N140° trending faults (notably the Sbiba, Kasserine and Gafsa faults) and was accompanied by an early halokinesis of the Triassic salts (Pertuisot, 1978). Ouali et al., 1986 and Martinez et al. (1987) explain the Aptian tectonism and the early Triassic halokinesis in the Tunisian Trough by an E-W directed extension episode related to an E-W transform zone along the northern margin of Tunisia. In the Tunisian Eastern Platform, minor rifts were developed and an accelerated subsidence is registered, accompanied by a basaltic magmatism (Fig. 6) (Burollet and Ellouz, 1986). This rifting episode, underlined by basaltic flows and dykes, affected also numerous regions in the equatorial Atlantic African margin and North-Arabia (Guiraud and Bellion, 1995). During the early Aptian, the direction of minimum stress in Africa changed from N-S to NE-SW (Guiraud et al., 1987). In northern Libya, the NW-SE trending Sirte trough developed at this time. In the Pelagian Sea, NW-SE trending rifts were formed (Marie et al., 1984). In short, the Aptian extension episode affected large domains in the African plate essentially on its margins. The tectonic extension phase which affected the northern part of the Auresian Basin, the Tunisian Atlas and the Tunisian eastern Platform, was registered also in the Pelagian block which is a part of the East Mediterranean Basin and corresponds with an abrupt modification of the African plate motion vector, which, at the anomaly M 0. (120.2 my) changed from an ESE-WNW to an ENE-WSW direction (Fig. 7). Latest Albian Rifting Episode The zones of North-Africa rifted during the Aptian and other regions located towards the interior of this domain are concerned by a renewed syndepositional tectonism during the Latest Albian. An accelerated subsidence (Fig. 6) concomitant with a tilting of blocks along the reactivated NW-SE trending faults occurred during the Latest Albian in the Aurès (Herkat, 1999) and also probably in the Tunisian basins. The amplitude of the subsidence was around 250 m. An early halokinesis of Triassic salts, succeeding to the tectonic extension

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episode occurring during the Latest Albian, is observed in the Tunisian Trough Lower Cenomanian (Perthuisot, 1978). During this period, the rifting never affected the Atlasic zones located westward the Aurès Basin, as the Eastern, Central and Western Saharan Atlas or the High Atlas of Morocco. However, an accelerated subsidence is observed during the Latest Albian times along the Atlantic margins of Africa, as the Benoué rift (Jansen, 1996; Guiraud, 1998) and the Essaouira Basin (Bouatmani et al. 2007), clearly linked to the separation of Africa and South-America at this period.

Latest Cenomanian to Early Turonian Rifting Episode This rifting episode marked by a tectonic extension along the NW-SE trending faults is still observed in the whole domain already affected by the Latest Albian episode (including the Aurès - Mellegue - Tunisian Basin) and furthermore in the Eastern Atlasic Basin and Preatlasic zone (Fig. 4) (Herkat, 1999; Touir, 1999; Zagrarni, 1999). Following this event, an accelerated subsidence is registered during the Early Turonian period reaching amplitude of 50 m approximately (Fig. 5). In the Oulad Nail Basin the synsedimentary tectonics allowed an early halokinesis and extrusion of the Triassic evaporites during the Early to Middle Turonian times (Herkat, 1992). A divergent dextral strike-slip affected the NNE-SSW trending Oulad Nail south-Atlasic fault, and had as a consequence a subsidence of the Saharan Platform (Herkat and Guiraud, 2006). This transtensional movement of the NNESSW south-atlasic fault was probably related to the anticlockwise rotation of Africa since the Mid-Cretaceous. Unconformities of the Lower Turonian on the Cenomanian series and small horst and graben structures in the Upper Cenomanian were observed in numerous regions of the Atlasic Domain (Herkat, 1999; Naili et al., 1995). In Tunisia, a reactivation of N-S and E-W trending faults occurred in the Sahel Margin (Bédir, 1995) involving unconformities of the Bahloul Formation (Latest Cenomanian to Lower Turonian) upon the Upper Cenomanian strata. In the Tunisian Through, an early halokinesis of the Triassic rocks is observed in the Lower Turonian (Ghanmi et al., (1999). In the Tunisian Atlas, an accelerated subsidence (Fig. 6) and a tilting of blocks along the NWSE directed faults are reported (Camoin, 1989; Boukadi and Bédir, 1996). During the Late Cenomanian to early Turonian period, the rifting did not affect the zones located westward the Oulad Nail Basin, as the Central and Western Atlas or the High Atlas of Morocco. Consequently it seems that since the Aptian period until the early Turonian times, the rifting has propagated westward, along the North-Africa margin, from Tunisia to Central Algeria (Fig. 2), affecting successively the Aurès and Eastern Saharan Atlas (Oulad Nail Basin). Eastward of the Tunisian Atlas, along the northern margin of Africa, the tectonic extension and associated accelerated subsidence observed in some basins of Libya and Egypt (Sirt and Abu Gharadig basins) according to Guiraud, (1998) suggests that the rifting affected also the entire northern margin of Africa. Therefore, globally, this tectonics is related with the evolution of the East Mediterranean Basin. The westward propagation of the tectonic extension episodes in North Africa is characterized by a weakening of the rifting importance and consequently of the tectonic subsidence amplitude from the first Aptian phase to the last Cenomanian phase. According to Mickus and Jallouli (1999), the thickest crust of 38–40 km is found under the Saharan Atlas, whereas the Tunisian Atlas has a crustal thickness comprised between 34 and 36 km. This decrease of the crustal thickness could reflect the influence of the Cretaceous extension

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phases more pronounced and numerous in its northeastern part, towards the East Mediterranean Basin.

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Senonian Compressional Events At the end of the Santonian period, the first early compressional events are registered in some regions of North Algeria. In the High Atlas, Western and Central Saharan Atlas, High Plateaus and Central Hodna Mounts, terrigenous deposits including sandstones and conglomerates were deposited until the Campanian times. The central Hodna Mounts, (Bertraneu, 1952; Guiraud, 1990) are subjected to the Santonian tectonic phase, involving local emergences during the Santonian and an unconformity of Campanian on the lower series, reaching the Lower Jurassic. The fold axes mainly present a NW-SE strike. This unconformity cannot be explained by halokinesis of the Triassic salts as proposed by Vially et al., (1994) knowing that folds are developed and the existence of widespread arenaceous influx. In the Western Atlasic Domain comprising the Ksour Mountains, the Djebel Amour and the Preatlasic zone, the Senonian is absent and conglomerates, siliciclastic, lacustrine or evaporitic deposits succeed the Turonian series. No deposits lying unconformably on these last Cretaceous deposits allow dating the age of the marine regression and deformation, but this one could probably be due to the Santonian compressional event, largely recognized in the African domain (Guiraud and Bosworth, 1997). Consequently, emersions are observed in numerous regions of the Atlasic domain during this compressional episode. During the Santonian (Khenchela region), an early halokinesis of the Triassic salts and their extrusion were registered (Lessart, 1955, Vila, 1980, Herkat, 1999). These extrusions could be related to the remobilization of the Triassic salts uplifted during preceding transtensional movements by the compressional movements exerted during the Santonian. The Aurès Basin is characterized by a migration of the depocenter zones from the centre of the Basin to its borders, towards the south and the north. This variation is interpreted by a compressive tendency exerted on this basin by the tectonic phase starting at the end of the Santonian (Herkat, 2004). In the Tunisian Atlas a high zone emerged in the Kasserine region, located in the southern Central Atlas (Burollet, 1956, Negra, 1994, Abdallah, 2000). However, in some regions as the Gafsa Basin a renewed subsidence was registered at the same time. Its signification is not well understood. It could be due to the compressive phase of the Santonian raising the Kasserine Island and sinking the south margin of the Atlas corresponding to the Gafsa Basin. The Latest Maastrichtian marks in several regions of the eastern Atlasic Domain an accentuation of the tectonic compression (Fig. 8) (Guiraud and Bosworth, 1997; Aris et al., 1998; Herkat, 1999; Herkat and Guiraud, 2006). This phase is marked by progressive unconformities of the Palaeogene upon the Maastrichtian in some regions as the Aurès Mounts and synsedimentary breccias and slips due to formation of marine slopes. In Tunisia, except the Tunisian Through and the Hammamet Gulf, in all other regions the Middle and Upper Maastrichtian are incomplete with gaps of certain terms. In the Kasserine Island all the Maastrichtian series is missing (Burollet and Desforges, 1982).

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Figure 8. Palaeostructural map of the eastern Atlasic Domain basins on Campanian- Maastrichtian. Localities: Symbols caption: 1: Unconformity, 2: Normal fault dip, 3: Inverse fault dip, 4: Dextral strike-slip fault, 5: Sinistral strike-slip fault, 6: High trend axis, 7: Subsident axis, 8: Triassic Diapirism, 9: Slumps, 10: Extension, 11: Late Maastrichtian compression, 12: Allochtonous.

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Tertiary Folding The fault pattern inherited from the Mesozoic extension was reactivated during the Cenozoic compression. The main folding phases in Morocco and Algeria Atlasic belt occurred at the end of the Priabonian and during the Latest Pliocene to early Pleistocene periods (Laffitte, 1939; Dubourdieu, 1956; Emberger, 1960; Bureau, 1986) and Guiraud, 1990). In the Tunisian Atlas, the main phases occurred during the Neogene times according to Burollet, (1956). The anomaly 34 my (Priabonian) marks a new inflexion of the trajectory of the African plate which changed from ENE-WSW to NE-SW (Fig. 7). At 24 my (beginning of the Aquitanian) the vector motion of the African plate changed northernward, which accentuated the compressional stresses on the northern margin of Africa and induced a remobilisation of the folds formerly structured by the Priabonian phase, as can be seen in the northern and southern borders of the Aurès Mounts (Laffitte, 1939; Aïssaoui, 1988; Gandriche, 1991).

PLATE KINEMATIC CONTROL ON THE ATLASIC DEFORMATIONS The main steps of African Plate motion path (Fig. 7) after the break up of the Pangea are related to the Atlantic Ocean opening and explain the geological evolution of the North

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African margin. During the Triassic to early Cretaceous times, the relative motion of Africa was essentially directed south-eastward. Since the Late Cretaceous times the African Plate underwent a counterclockwise rotation converging toward Eurasia. From the Oligocene to Burdigalian period the African plate drifts towards the NNE, and then from Langhian to early Tortonian time this drift is towards the NNW. From the late Tortonian its path is northwestward (Mazzoli and Helman, 1994). The tectonic extension in the Atlasic Basins occurred in three steps, first during the Triassic-Jurassic, second, with a different orientation of the stresses, during the Cretaceous and third during the Tertiary. The minimum stress directions during the first two successive phases were orthogonal one relative to the other. Moreover, the different segments of the chain did not register all the tectonic distension episodes. The Western High Atlas Basin became stable since the Middle Jurassic when the Eastern Aurès-Tunisian Basin evolved in extension until the Cretaceous. The main phases of tectonic processes occurring in the North-African belt since the Triassic and highlighted by the accelerated subsidence phases follow the directions of the African plate drift (Table 1). The minimum stresses corresponding to the tectonic tensional phases, are nearly parallel to the directions of drift of the African plate during each phase of the Mesozoic evolution. The maximum stresses marking the compressional phases are also dependable of the direction of drift of the plate which changed progressively northernward (Table 1). -

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-

-

From 220 to 195 my corresponding to the Late Triassic and Early Lias period, a rifting initiated in the Central Atlantic according to a WNW-ESE direction. This period was marked in the Atlasic Basins by a significant rifting in the westernmost zones as the High Atlas, and Saharan Atlas and in the coastal Atlantic Basins. From 176.5 to 169.2 my, through the Bajocian times, an extensional phase is observed in the High Atlas and Saharan Atlas. The Atlantic coastal basins were preserved from this phase which let suppose that this extension is rather in relation with the Maghrebian-Liguride Basin evolution. From 154 to 146.7 my, during the Late Kimmeridgian - Late Tithonian, the direction of drift of the African Plate was still south-eastward. This event corresponds with a renewed tectonic extension in the Central and Eastern Saharan Atlas Basins. The Western Saharan Atlas and the Moroccan Atlas remained stable, except the Atlantic margin (Agadir Basin) where an extension phase is registered.

Consequently, during the Triassic and Jurassic the tectonic extension propagated from west to east, concerning successively the Western zones (Atlantic Ocean, Moroccan Atlantic coastal basins and High Atlas), where the main extension phase occurred during the Late Triassic times, then the Saharan and Tunisian Atlas where the extension was more pronounced during the Lias period and which registered a late Jurassic extension phase. -

At 120 my, during the Early Aptian, the ESE direction of drift of Africa changed brusquely to ENE direction, in relation with the onset of drifting of the South Atlantic Ocean (Guiraud and Bosworth, 1997). This episode marks the transition from the High Atlas, Saharan Atlas, Atlantic and Maghrebian Ocean extensional phases to phases registered essentially in the Aurès-Tunisian Atlas and in the

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southern margin of the East Mediterranean Basin. The direction of the minimum stress changed to SW-NE to ENE and was synchronous with a motion of the plate in the same direction. Between 120 my, (Latest Albian) and 34 my (Priabonian), the detailed cinematic data are absent but the African plate drift experienced a progressive counterclockwise rotation, well shown in its trajectory (Rosenbaum, 2002). Two tectonic extension phases occurred, first at the end of the Albian period (98.9), marking the crustal separation of Africa and South America and at the end of the Cenomanian period (93.5). These phases extended progressively westward, concerning successively, the Western Aurès Basin and the Oulad Nail Basin (Table 1) and show a progressive decrease of the tectonic subsidence, from the Aptian phase to the latest Cenomanian phase.

In summary, the Cretaceous evolution is marked by a propagation of the tectonic extension from the easternmost zones in the Pelagian block (Eastern Mediterranean Basin) and Atlas of Tunisia to the western ward zones in the Eastern Saharan Atlas of Algeria. An evaluation of the tectonic processes developing during the three steps of evolution of the North-Africa Atlasic belt enables to conclude that in all cases the propagation of the tectonic extension proceeded from ocean towards continent, therefore during the Triassic to Jurassic period the rifting propagated eastward the Atlantic Ocean, when during the Cretaceous times, it propagated westward the Eastern Mediterranean Basin. The Triassic and Jurassic rifting phases were followed by a progressively infilling of the developed basins. Even if compression phases were not registered in these Western Atlasic basins, the rifting processes aborted. The comparison of the vector motion of the African Plate during the Jurassic period (Fig. 7) with the direction of the minimum stress shows that they were parallel. Therefore the minimum stress was probably parallel with the direction of opening of the Atlantic and Maghrebian - Liguride Oceans. From the Aptian to Santonian times a counterclockwise rotation induced a change in the direction of the extension in the Atlasic Basins which changed to north-eastward. This fact may be explained by the relationships of the extension process with the azimuth of the inherited faults. Indeed, in this case, the normal movement of the NW-SE trending basement faults is parallel with the ENE to NE direction of the minimum stress. The Late Cretaceous to Neogene period marks the onset of the Eurasian and African colliding and a NNW to northernward drift of Africa parallel with the direction of the maximum stress, as observed nowadays in the converging plate boundary zones (Zoback, 1994)

NEOTETHYS AND NORTH-EASTERN ATLASIC DOMAIN PALEOTECTONICS The tectonic processes in the North-eastern Atlasic Basins are related during certain periods to the Neotethyan evolution. The paleotectonic and paleogeographic evolution of this ocean is summarized essentially for its south margin, which corresponds to the northern part of Africa Plate.

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Overview of the Tunisian and Libyan Margin Along the Mediterranean African margin, Permian, Triassic and Early Jurassic faulting and igneous activity imply that in some segments of the East Mediterranean Basin, Triassic or even Permian rifting could be envisioned (Garfunkel, 1998, 2004). However, in this margin, Triassic and Jurassic structural trends may have been overprinted by the Mid Cretaceous rifting.

Pelagian Sea

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In the Sicilian-Tunisian area, the extension of platform carbonates shows that this zone represented the extension of Africa during Cretaceous times. The Pelagian shelf was affected by Cretaceous faulting (Fig. 9 and 10) accompanied by volcanism, related to the Sirte rifts (Biju Duval et al., 1977).

Figure 9. Simplified structural map of the Northeast of Tunisia, North of Libya and of the Pelagian Sea showing the main faults. After Klett (2001), modified.

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Figure 10. Palinspatic section of the Pelagian block at the end of the Paleocene period (reconstructed from sections in Ahlbrandt, (2001), modified. Legend: HGF: Hamimat and Gafsa Fault. Location in the figure 9.

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These faults were reactivated during the Neogene times. The present map of the Pelagian Sea (Fig. 9) shows also numerous structural highs lying between the North African margin and Sicily. According to Anketell, (1996) and Guiraud and Bosworth, (1997), the Pelagian province was characterized during the Cretaceous period by an extensional dextral strike-slip faulting system.

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Sirte Basin The Sirte Basin (Fig. 1) is a triple-junction continental rift along the northern margin of Africa (Ahlbrandt, 2001), on the south of the Gulf of Sirte. The Sirte Basin shows a regional uplift of the basement referred to as the Sirte Arch (Anketell, 1996). The timing of this uplift is not well known, classically considered to be a mid-Paleozoic event, it could have formed in the Mesozoic before an Early Cretaceous rifting event (Ahlbrandt, 2001). According to Anketell (1996), Guiraud and Bosworth (1997), the Cretaceous rifting reflected EW shear zones. The Late Cretaceous rifting episode was characterized by the development of several northwest-southeast trending horsts and grabens that step progressively downward to the east; these structures pass northward to the Ionian Abyssal Plain underlain by oceanic crust which is being subducted to the north beneath the Hellenic arc (Garfunkel, 1998). The ages of the Sirte sedimentary pile is poorly constrained which prevents the dating of the main tectonic events. In particular, the age of the rifting episode during the Early Cretaceous could have initiated during the Aptian knowing that this extension phase affected the neighbouring East-Tunisian Platform and the Pelagian Sea (Fig. 10). The Late Cretaceous extensional events, in the same reasoning, could correspond to the Latest Albian and Latest Cenomanian phases. However, it is likely that the main Cretaceous phase of subsidence occurred during the Senonian which constitutes the thickest sedimentary unit in this Basin. An accelerated subsidence is observed also during the Paleocene times (Ahlbrandt, 2001). The interpretation of this strong Senonian subsidence is uncertain. Giving that this period is characterized by a counterclockwise rotation and north-eastward drift of Africa, extensional processes are difficult to explain. However, wrench induced pull-apart basins may develop, even in a compressional setting.

Plate Tectonics and Neotethys Evolution The consequences of the Plate tectonics on the evolution of the North African margin since the Late Paleozoic to the Cenozoic period may be resumed in successive steps:

Late Permian to Early Jurassic The Late Permian separation of the Cimmerian terranes from the northeastern margin of Gondwana and the opening of the Neotethys Ocean was probably governed by slab-pull forces related to subduction of the PaleoTethys Ocean beneath the southern margin of Eurasia (Robertson et al., 2004). Carboniferous and early Permian rifting preceding the separation of Cimmerian blocks (Iranian Terranes) from Arabia propagated westwards into the Eastern

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Mediterranean Domain and culminated in the Permian detachment of the Apulian-Taurus Terrane from northeastern Africa and the Levant Margin of Arabia (Stampfli et al., 2001). However the East Mediterranean branch of the Neotethys sea-floor spreading axis apparently became inactive.

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Cretaceous According to Dercourt et al., (1986, 1993, 2000) and Scotese (1988), at the beginning of the Late Cretaceous, Africa was separated from other continents by active sea-floor spreading axes except at its northeastern margin in which the subduction of the oceanic part of the African plate corresponding to the Neo-Tethys domain started. In more recent interpretations, the plate reconstructions of Stampfli and Borel, (2002, 2003) show inactive spreading centres in the Neotethys and unvarying paleogeography of the East Mediterranean Basin during this period. In this case, the tectonic extension which occurred in the northeast African margin during the Cretaceous period cannot be related to a drifting oceanic process in the Neotethys. Other origins have to be envisioned. This extension could be explained by the azimuth of the direction of vector motion of the African Plate drift and of the tectonic minimum stress, roughly orthogonal to the direction of the crustal weakness zones. Indeed, these zones, corresponding to the basement faults, NWSE striking, are susceptible to be reactivated as normal faults. The Cretaceous extension phases did not affect the EMB and the Northeastern African Domain in homogenous way. Some zones are more remobilized and rifted than others; the Atlasic Basins show numerous tilted blocks from the southeast to the northeast (Fig. 3c), when the Pelagian Block is less stretched (Fig.10). The more faulted Maghrebian Atlasic Domain was probably limited from the more stable Pelagian Domain by a NNE-SSW or NE-SW trending fault passing on the northwest margin of Sicily. Strike-slip systems could have favoured this extension as described in some regions of the EMB south margin. The Cretaceous rifting event is characterized by the formation of a series of northwest-trending horsts and grabens in the Sirte Basin that step progressively downward to the east, where dominantly EW trending rifts are observed in the Abu Gharadig Basin. According to Anketell (1996), the Early Cretaceous rifting reflected east-west sinistral shear zones, when Guiraud and Bosworth (1997) proposed that dextral shear forces dominated Late Cretaceous tectonism. In a comparable approach, a model of rifting is proposed in the following concerning the Northeastern Atlasic Domain which does not require tectonic extensional processes driven by an active spreading centre in the East Mediterranean Basin. This domain could have registered a sinistral transtensional movement of the North Atlasic fault during the Aptian to Turonian period, involving the reactivation of the NW-SE trending faults inside these basins as normal faults and the development of intensive block-faulting. The lateral transition from stretched zones with numerous tilted blocks near the North Atlasic fault in Western Aurès to zones less stretched eastwards in the Eastern Aurès (Hamimat region) as observed in seismic sections suggests that the tectonic extension was more intensive close to the northwest margin of the Eastern Saharan Atlasic, Aurès and Tunisian Atlasic Basins (Herkat, 1999). These features point towards a syndepositional transtensional mobility of the North Atlasic fault. To be consistent with the NW-SE trending normal faults, the divergent wrench North Atlasic

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fault movement could have been left-lateral. This sense is compatible with the direction of the motion vector of the Plate at these times which was ENE (Herkat, 1999, Herkat and Guiraud, 2006). Dextral transtensional movements could have affected the South Atlasic fault bordering the Aurès Basin along the Kasserine mole, which have already been suggested for the NE trending Saharan South Atlasic fault at this period (Herkat, 1999; Herkat and Guiraud, 2006). In this case the bottom of the Atlasic African basins, crosscut by NE-SW trending faults, could have slipped North-eastward inducing the reactivation of the NW-SE trending faults limiting the tilted blocks. Their increasing throw near the North Atlasic margin was probably due to the similar ENE-WSW direction of the motion vector of the African Plate and of the North Atlasic fault movement, allowing extensional strike slips. In the case of the Atlasic southern margin, the direction of the vector motion of the plate is oblique relative to that of the NE-SW trending South Atlasic fault, which had as effect to diminish the extensional tectonics in this zone. The more intensively faulted basement of the Atlasic basins basement was an essential cause of its preferential sliding north-eastwards relative to the Preatlasic and Saharan domains less fractured, involving an increasing subsidence from southeast to northeast. The accelerated subsidence observed during the Senonian period in the Sirte and Abu Gharadig Basins (Moustafa and Khalil, 1990) predates the general inversion affecting the whole northern African margin (Bosworth et al., 1999). Its origin could be related to the obduction of ophiolites beneath the Arabian promontory (Garfunkel, 1998). This event is marked by the reactivation of preexisting normal faults in rifting-like processes (Kuss, 1992). However the precise tectonic mechanisms of this reactivation are still not resolved.

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Tertiary During the Paleocene times, in the Sirte Basin an active subsidence continued, suggesting the occurrence of the same tectonic processes registered during the Senonian period in this region. Since the Eocene period the African Plate path was towards the NNW, inducing that the Atlasic Domain was evolving in compression and folding marked by successive phases culminating during the Middle Eocene. Renewed compressional phases occurred during the Late Pliocene.

CONCLUSION -

-

The evolution of the Atlasic chain shows polyhistory extension and compression phases, related to various inherited tectonic settings, mainly represented by the Precambrian and Paleozoic deep-sealed faults. The main factor controlling the tectonic evolution of the Northeast African margin was the opening of the Atlantic Ocean and its progressive drifting in successive phases from the central to the southern part during the Jurassic times. The Maghrebian Ocean contributed also probably during the Middle to Late Jurassic period to influence the tectonic extension of the African margin and Atlasic basins.

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-

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The development of extensional processes in the Northeastern Atlasic basins of Africa during the Aptian to Turonian Period could be a consequence of the development of transtensional wrench fault systems on the northern margin of the African Plate. However, accurate Plate tectonic reconstructions and syndepositional tectonic studies are necessary to elucidate the precise mechanisms at the origin of this rifting. The direction of the minimum stresses of the successive extension phases was parallel to the vector motions of the African plate during the Triassic to Cretaceous rifting period. The direction of the maximum stress during the Cenozoic times was parallel or sub parallel also with this vector motion in the Atlasic Basins which were located in the converging zone between the Eurasian and African Plates. The first compressive phases in the Atlasic belt initiated during the Senonian period and concerned mainly the western zones of the chain but were registered also in the southern part of the North-south Axis high Zone in Tunisia. The major folding phase occurred during the Paleogene times in the central and eastern parts of the chain, and during the Neogene at its western and eastern margins. Multiphase tectonism and synsedimentary structuring are therefore characteristic features of the Atlasic chain which acquired its geometry and structure progressively during the Mesozoic and Cenozoic times.

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REFERENCES Abdallah, H. 2000. Stratigraphie intégrée et paléogéographie des séries sédimentaires à la limite Cénomanien-Turonien en Tunisie méridionale, Unpublished Doctorat d’état Thesis, Université of Tunis II. Abed, S. 1982. Lithostratigraphie et sédimentologie du Jurassique moyen et supérieur du Dj. Amour (Atlas Saharien. Thèse, Univ. de Pau. Ahlbrandt, T. S., 2001. The Sirte Basin Province of Libya—Sirte-Zelten Total Petroleum System. U.S. Geological Survey Bulletin 2202–F. This publication is available online at: http://geology.cr.usgs.gov/pub/bulletins/b2202-f/. Aissaoui D. (1985).- Les structures liées à l’accident sud-atlasique entre Biskra et le Dj. Mandra. (Algérie). Evolution géométrique et cinématique. Thesis, Strasbourg, 145 p. Ait Ouali R. 1991. Le rifting des Monts des Ksours au Lias: Organisation du bassin, diagénèse des assises carbonatées, place dans les ouvertures mésozoïques au Maghreb. Thèse Doct. ès Sci. U.S.T.H.B. 302 p. Ait Ouali, R. et Delfaud, J. 1995. Les modalités d’ouverture du bassin des Ksours au Lias dans le cadre du “ rifting ” jurassique au Maghreb. C.R.Acad Sci. Paris. t. 20, série II a, p. 773 à 778. Amrhar, M., 1995. Tectonique et inversions géodynamiques post-rift dans le Haut Atlas occidental. Structures, instabilités tectoniques et magmatismes liés à l’ouverture de l’Atlantique central et la collision Afrique-Europe. Thesis, Université Cadi Ayyad, Marrakech.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Copyright © 2009. Nova Science Publishers, Incorporated. All rights reserved.

338

Missoum Herkat

Anketell, J.M., 1996. Structural history of the Sirt Basin and its relationships to the Sabratah Basin and Cyrenaican Platform, Northern Libya, in Salem, M.J., El-Hawat, A.S., and Sbeta, A.M., eds., The geology of Sirt Basin: Amsterdam, Elsevier, v. III, p. 57–88. Arboleya, M.L., Teixell A., Charroud M., Julivert M. 2004. A structural transect through the High and Middle Atlas of Morocco. Journal of African Earth Sciences 39 (2004) 319– 327. Aris, Y., Coiffait, P. E., & Guiraud, M., 1998. Characterization of Mesozoic – Cenozoic deformations and palaeostress fields in the Central Constantinois, northeast Algeria. Tectonophysics, 290, 59-85. Asfirane, F. 1994. Traitement et analyse qualitative des données aéromagnétiques acquises au dessus de l’Algérie du Nord, Impact sur la géologie de la chaîne atlantique. Thèse de Doct. ès Sci. Paris XI. Beauchamp, J. 1983. Le Permien et le Trias Marocains, in Colloque sur le Permien et le Trias du Maroc, Bull. Fac. Des Sciences, Université cadi Ayad, n° sp., 1-21. Bédir, M., 1995. Mécanismes géodynamiques des bassins associés aux couloirs de coulissements de la marge atlasique de la Tunisie. Seismostratigraphie, seismotectonique et implications pétrolières. Thèse ès Sciences, Univ. Tunis II, Tunisia, 412 p. Ben Ayed, N., 1986. Evolution tectonique de l’avant-pays de la chaîne alpine de Tunisie du début du Mésozoïque à l’actuel. Thèse ès Sciences, Univ. Paris-sud, Orsay, France, 347p. Bertraneu J. 1955. Contribution à l’étude géologique des Monts du Hodna. 1) Le massif du Bou Taleb Bull. Serv. Geol. de l’Alg., n.s. (4) 190 p. Thèse. Algiers. Biju-Duval, B., Dercourt, J., Le Pichon, X., 1977. From the Tethys Ocean to the Mediterranean Seas: a plate tectonic model of the evolution of the Western Alpine system. In: Biju-Duval, B., Montadert, L. (Eds.), International Symposium on the Structural History of the Mediterranean Basins (Split, 1976). Editions Technip, Paris, pp. 143– 164. Bouatmani, R., Chakor Alami A. and Medina F. Subsidence, évolution thermique et maturation des hydrocarbures dans le bassin d'Essaouira (Maroc) : apport de la modélisation. Bulletin de l’Institut Scientifique, Rabat, section Sciences de la Terre, 2007, n°29, 15-36. Bouaziz, S., 1995. Etude de la tectonique cassante dans la plate-forme et l’Atlas saharien (Tunisie méridionale). Evolution des paléochamps de contraintes et implications géodynamiques. Thèse ès Sciences, Univ. Tunis II, Tunisia, 485p. Boukadi, N., 1994. Structuration de l’Atlas de Tunisie. Signification géométrique et cinématique des nœuds et des zones d’interférences structurales au contact de grands couloirs tectoniques. Thèse ès Sciences, Univ. Tunis II, Tunisia, 249 p. Boukadi, N., Bédir, M., 1996. L’halocinèse en Tunisie. Contexte tectonique et chronologie des évènements. C.R. Acad. Sci. Paris 322, 587–594. Bosworth, W., R. Guiraud and Kessler L.G. 1999. Late Cretaceous (ca. 84 Ma) compressive deformation of the stable platform of Northeast Africa (Egypt): far-field stress effects of the “Santonian Event” and origin of the Syrian Arc Deformation Belt. Geology, v. 27/7, p. 633–636. Bouillin, J.P. and Kornprobst, J., 1974. Associations ultrabasiques de Petite Kabylie: péridotites de type alpin et complexe stratifié; comparaison avec les zones internes Bético-rifaines. Bull. Soc. Géol. Fr., 16: 101-237.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Copyright © 2009. Nova Science Publishers, Incorporated. All rights reserved.

Geodynamic Evolution of the North African Atlasic Belt

339

Bourezg S. 1984. Evolution géodynamique de la bordure fragile sud-mésétienne: le Dj. Nador de Tiaret. Etude sédimentologique et structurale. Thesis Univ. de Pau. 215 p. Bracène, R. 2001, Géodynamique de l’Algérie du Nord : impact sur l’exploration pétrolière, thèse, université de Cergy-Pontoise, vol. 1, 2001, 84 p. Bracène R., Patriat M., Ellouz N., Gaulier J.M. 2003. Subsidence history in basins of northern Algeria. Sedimentary Geology 156 (2003) 213–239. Bureau, D. 1986. Approche sédimentaire de la dynamique structurale: Evolution mésozoïque et devenir orogénique de la partie septentrionale du fossé saharien. (Sud-ouest constantinois et Aurès-Algérie). Thèse Sci. Univ. Pierre et Marie Curie, Paris. 2 vol. 779 p. Burollet, P.F., 1956. Contribution à l’étude géologique de la Tunisie centrale. Ann. Mines et Géol. Tunis, 18, 350 p. Burollet, P.F. et Ellouz N. 1986. L’évolution des bassins sédimentaires de la Tunisie centrale et orientale. B.C.R.D.Pau. N° 10, p. 49-68. Burollet, P.F.et Desforges D. 1982. Dynamique des bassins Néocrétacés en Tunisie. In livre jub. G. Lucas: Mém. Dijon, (7), p. 381-389. Caby, R., 1970. La chaîne Pharusienne dans le NW du Ahaggar (Sahara central ; Algérie) : sa place dans l’orogenèse du Précambrien supérieur en Afrique. Thèse Sci.Université de Montpellier. France. Publication de la Direction des Mines et de la Géologie, Alger, Algérie, 47, 289 p. Camoin, G. 1989. Les plateformes carbonatées du Turonien et du Sénonien de Méditerranée centrale (Tunisie, Algérie et Sicile); Thèse Doct. ès Sci. Univ. Provence. Canérot, B., Andreu-Boussut, B., Chafiki, D., El Hariri, Kh. and Souhel, A. 2003. Mesozoic carbonate platforms and associated siliciclastic spreadings in Morocco, North African Cretaceous Carbonate Platform Systems. NATO Science Series. Edited by Eulalia Gili, Mohamed El hedi Negra and Peter Skeleton. Kluwer Academic Publishers. Dordecht / Boston/ London, 19-29. Charrière, A. 1990. Héritage Hercynien et évolution géodynamique alpine d’une chaine intracontinentale: le Moyen Atlas au SE de Fès (Maroc) Thèse Sciences, Toulouse (France). Chihi, L. 1995. Les Fossés néogènes et quaternaires de la Tunisie et de la Mer pélagienne : leur étude Structurale et leur Signification dans le Cadre géodynamique de la Mediterranée centrale. Thèse de Doctorat. Université de Tunis II. Choubert, G., and Faure-Muret, A. 1962. Evolution du domaine atlasique marocain depuis les temps paléozoïques, in Livre à la mémoire du prof. Paul Fallot, Soc. Géol. De France, Paris, Mem. Spécial, I, 447-514 Dercourt, J., Zonenshain, L.P., Ricou, L.E., Kazmin, V.G., Le Pichon, X., Knipper, A.L., Grandjacquet, C., Sbortshikov, I.M., Geyssant, J., Lepvrier, C., Pechersky, D.H., Boulin, J., Sibuet, J.-C., Savostin, L.A., Sorokhtin, O., Westphal, M., Bazhenov, M.L., Lauer, J.P., Biju-Duval, B., 1986. Geological evolution ofthe Tethys belt from the Atlantic to the Pamirs since the Lias.Tectonophysics 123, 241–315. Dercourt, J., Ricou, L. E & Vrielinck, B., 1993. (eds), Atlas Tethys Paleoenvironmental maps, Gauthiers-Villars, Paris, 307 p. Dercourt, J., Gaetani, M., Vrielinck, B., Barrier, E., Biju-duval, B., Brunet, M. F. ,Cadet, J. , Crasquin, S. & Sandulescu, M.. 2000. (eds), Atlas Peri-Tethys Paleoenvironmental maps, Explanatory notes. Paris 2000.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Copyright © 2009. Nova Science Publishers, Incorporated. All rights reserved.

340

Missoum Herkat

Dewey, J.F., Helman, M.L., Turco, E., Hutton, D.H.W., Knott, S.D.1989. Kinematics of the western Mediterranean. In: Coward,M.P., Dietrich, D., Park, R.G. (Eds.), Alpine Tectonics. Geological Society, London, Special Publication, pp. 265–283. Dubourdieu, G., 1956. Etude géologique de la région de l’Ouenza (confins AlgéroTunisiens). Publ. Serv. Carte Géol. de l’Algérie, n.s., n° 10, 659 p. Elmi, S., 1978. Polarité tectono-sédimentaire pendant l’effritement des marges septentrionales du bâti africain au cours du Mésozoïque (Maghreb). Ann. Soc. Geol. Nord XCVII, 315– 323. Elmi, S., Alméras, Y., Ameur, M., Atrops, F., Benhamou, M., Moulan, G., 1982. La dislocation des plateformes carbonatées liasiques en Méditerranée occidentale et ses implications sur les échanges fauniques. Bull. Soc. Geol. Fr. XXIV (56), 1007–1016. Emberger, J. 1960. Esquisse géologique de la partie orientale des Monts des Oulad Naïl, Atlas Saharien. Publ. Serv. Carte. Géol. Alg., n.s., n° 27, 400 p., 87 fig. Feddan, B. 1989. Evolution géodynamique d’un bassin intraplaque sur décrochements : le Moyen Atlas (Maroc) durant le Méso-Cénozoique, Trav. Inst. Sci. Rabat 18 (1989), 142. Garfunkel, Z. 1998. Constraints on the origin and history of the Eastern Mediterranean basin. Tectonophysics 298, 5 –35. Garfunkel, Z. 2004. Origin of the Eastern Mediterranean basin: a reevaluation. Tectonophysics 391 (2004) 11 –34. Ghandriche, H., 1991. Modalités de la superposition de structures de plissementchevauchement d’âge alpin dans les Aurès (Algérie). Thèse, Univ. Paris Sud, Orsay, 190 pp. Ghanmi, M., Vila J.-M., Ben Youssef M., Bouhlel S., Kamoun F. 1999. Place du « glacier de sel » sous-marin résiduel turonien de la Koudiat Sidii (Nord-Ouest tunisien), dans le contexte halocinétique de la transversale des confins algéro-tunisiens (Nord-Est du Maghreb), comparé à celui de la marge passive de Louisiane, Bull. Soc. Hist. Nat. Gradstein, E. M., Agterberg F. P., Ogg J. G., Hardenbol J., Van Veen P., Thierry J., Huang Z., 1995. A Triassic, Jurassic and Cretaceous time scale, in Berggren, W. A., Kent D. V., Aubry M. P., and Hardenbol J., eds. Geochronology. Time scales and Global Stratigraphic Correlation: Tulsa, SEPM Special Publication 54, 95-126. Guiraud, R., 1990. Evolution post-triasique de l’avant-pays de la chaîne alpine en Algérie, d’après l’étude du Bassin du Hodna et des régions voisines. Geological Survey of Algeria, Memoir 3. 259 p. Guiraud, R., 1998. Mesozoic riting and basin inversion along the northern African Tethyan margin: an overview. In: Macgregor, D.S., Moody, R.T.& Clarck-Lowes, D.D. (eds) 1998. Petroleum Geology of North Africa. Geological Society, London, Spec. Pub., n° 132, 217-229. Guiraud, R., Bellion, Y., Benkhelil, J., Moreau, C., 1987. Post-Hercynian tectonics in Northern and Western Africa. In: Nature 228, 453 Bowden, P., Kinnaird, J. (Eds.), African Geology Reviews. Geol. J. 22, 433–466. Guiraud, R. and Bosworth, W., 1997. Senonian basin inversion and rejuvenation of rifting in Africa and Arabia : synthesis and implications to plate -scale tectonics, Tectonophysics, 282, 39-82. Guiraud, R. and Bosworth, W. 1999. Phanerozoic geodynamic evolution of northeastern Africa and the northwestern Arabian platform. Tectonophysics, 315, 73-108.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Copyright © 2009. Nova Science Publishers, Incorporated. All rights reserved.

Geodynamic Evolution of the North African Atlasic Belt

341

Haller, P. 1983. Structure profonde du Sahel tunisien. Interprétation géodynamique. Thèse 3ème cycle, Univ. Franche-Comté, 162 p. Besançon. Herkat, M., 1982. Lithostratigraphie et sédimentologie des formations carbonatées du Jurassique supérieur des Monts des Oulad Nail et de la terminaison orientale du Djebel Amour, (Atlas saharien). Unpublished thesis, University of Pau. France Herkat, M., 1992. Manifestations diapiriques du Trias dans les séries du Crétacé supérieur de l’Atlas saharien et des Aurès. Bull. du Serv. Géol. de l’Algérie, 3, n° 1, 15-27. Herkat, M., 1999. La sédimentation de haut niveau marin du Crétacé supérieur de l’Atlas saharien oriental et des Aurès. Stratigraphie séquentielle, analyse quantitative des biocénoses, évolution paléogéographique et contexte géodynamique. Unpublished thesis, University of Algiers USTHB. Algeria. 802 p. Herkat, M. 2004. Contrôle eustatique et paléogéographique de la sédimentation du Crétacé supérieur du basin des Aurès (Algérie). Bull. Soc. Géol. Fr. n° 3, t. 175, 273-288. Herkat, M., Guiraud R. 2006. The relationships between tectonics and sedimentation in the Late Cretaceous series of the eastern Atlasic Domain (Algeria). Journal of African Earth Sciences. Vol. 46, 4, 346-370. Herkat, M. 2008. Sequence Stratigraphy and Palaeogeographic Context of the Saharian Atlas (Algeria) Upper Jurassic. 26th IAS Meeting of Sedimentology Bochum, Germany 1-3 September 2008. Idres, M. and Aifa, T. 1995. Some parameters to improve a gravity network accuracy: application to the new reference base stations network of the North of Algeria. Bul.Serv. Géol. De l’Algérie. Vol. 6, n°1, 79-94. Jansen, Maria Elisabeth. 1996. Intraplate deformations in Africa as a consequence of plate boundary changes. Inferences from subsidence analysis and tectonic modelling of the Early and Middle Cretaceous period. Vrije University. Kazi Tani, N., 1986. Evolution géodynamique de la bordure nord-africaine: le Domaine intraplaque nord-algérien. Approche mégaséquentielle. Unpublished thesis, University of Pau. 871 p. Klett, T.R. 2001. Total Petroleum Systems of the Pelagian Province, Tunisia, Libya, Italy, and Malta—The Bou Dabbous– Tertiary and Jurassic-Cretaceous Composite. U.S. Geological Survey Bulletin 2202–F. This publication is available online at: http://geology.cr.usgs.gov/pub/bulletins/b2202-d/. Kuss, J. 1992. The Aptian-Paleocene shelf carbonates of northeastern Egypt and southern Jordan: establishment and break-up of carbonate platfoms along the southern Tethyan shores. Zeitschrift der deutschen geologischen Gesellschaft, v. 143, p. 107–132. Laffitte, R., 1939. Etude géologique de l’Aurès. Thèse Sci. Paris. Bull. du Serv. Géol. de l’Algérie. 1° série. n° 11, 484 p., 1 carte au 1/200 000. Laville, E. 1985. Evolution sédimentaire, tectonique et magmatique du bassin Jurassique du Haut Atlas (Maroc): modèle en relais multiples de décrochements. Thèse d’Etat. Montpellier. 168 p. Laville, E., Lesage, J.-L., Séguret, M., 1977. Géometrie, cinématique (dynamique) de la tectonique atlasique sur le versant sud du Haut Atlas marocain. Aperçu sur les tectoniques hercyniennes et tardihercyniennes. Bulletin de la Societé géologique de France (7) 19, 527–539.

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Missoum Herkat

Lessard L. 1955. Faciès bréchiques dans le Crétacé superieur d’âge des premières manifestations diapiriques du Trias prés de Khenchela. B.S.G.A., n.s., n° 5, p. 381-390, 1 pl. h. t. Marie, J., Trouvé, P., Desforges, G., Dufaure, P., 1984. Nouveaux éléments de paléogéographie du Crétacé de Tunisie. Notes et Mémoires TOTAL-CFP, Paris, France 19, 7–37. Martinez, Cl., Chikhaoui M. and Elsass, Ph. 1987. Le « Diapir » de Nebeur (Tunisie septentrionale) Géométrie des accidents distensifs synsédimentaires crétacés et leur rôle lors des serrages alpins. Rev. Sc ; de la Terre, Vol. 6, Tunisie.25-36. Masse J.P. et Thieuloy J. P. 1979. Précisions sur l’âge des calcaires et des formations associées de l’Aptien sud-constantinois. B.S.G.F. (7), T. XXV, n° 1, p. 65-71. Mattauer, M., Tapponnier, P. and Proust, F. 1977. Sur les mécanismes de formation deschaînes intracontinentales : l’exemple des chaînes atlasiques du Maroc, Bull. Soc. géol. France 19, 521–526. Mazzoli, S. and Helman, M., 1994, Neogene patterns of relative plate motions for AfricaEurope: some implications for recent central Mediterranean tectonics: Geologische Rundschau, v.83, pp. 464-468. Michard, A. 1976. Eléments de géologie marocaine. Notes et Mémoires : Service Géol. du Maroc, n° 252. Mickus, K. and Jallouli, C., Crustal structure beneath the Tell and Atlas Mountains (Algeria and Tunisia) through the analysis of gravity data, Tectonophysics 314 (1999) 373– 385. Moustafa, A.R. and Khalil, M.H. 1990. Structural characteristics and tectonic evolution of north Sinai fold belts. In: The Geology of Egypt (Ed. R. Said), pp. 381–389. Balkema,Rotterdam. Mrabet, A. 1981. Stratigraphie, sédimentologie et diagenèse carbonatée des séries du Crétacé inférieur de Tunisie centrale. Thèse d’état. Univ. d’Orsay, Paris. Naïli, H., Belhadj, Z., Robaszynski, F. and Caron M. 1995. Présence de roches mères à facies Bahloul vers la limite Cénomanien-Turonien dans la région de Tébessa (Algérie orientale). Notes du Service de Tunisie, 1995, n° 61, 19-32. Negra, M. H. 1994. Les dépôts de plate-forme à bassin en Tunisie Centro-septentrionale. Sédimentation et diagenèse des séries du Crétacé supérieur (formation Abiod et faciès associés).Stratigraphie, Sédimentation, Diagenèse et Intérêt pétrolier. Thèse de Doctorat ès-Sciences. Université de Tunis. Ouali, J. 1984 ; Structure et évolution géodynamique du chainon Nara-Sidi Khalif (Tunisie Centrale). Thèse 3ème cycle, Rennes, 120 p. Ouali, J., Martinez C. and Khesibi M. 1986. Caractères de la tectonique crétacée en distension au Jebel Kebar (Tunisie Centrale) : ses conséquences. Cahiers de Géodynamique, n°1 (1) ORSTOM, Paris. Perthuisot, V., 1978. Dynamique et pétrogenèse des extrusions triasiques en Tunisie septentrionale. Thèse ès Sciences, Trav. Lab. Géol. (Eco. Norm. Sup.), Paris, 312p Perthuisot, V. and Rouvier, H. 1990. Halocinèse et plate-formes en extension ou, coulissement : le Maghreb oriental au Mésozoique. Comparaison avec la rive septentrionale de la Tethys. 2ème congrès national des Sciences de la Terre. Tunis, 1990. Piquet, A., Tricart, P., Guiraud R., Laville, E., Bouaziz, S., Amrhar, M. et Ait Ouali, R. 2002. The Mesozoic-Cenozoic Atlas belt (North Africa) : an overview. Geodinamica Acta, 15 185-208.

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Reicherter, K.R.1; Pletsch, T.K.2. 2000. Evidence for a synchronous circum-Iberian subsidence event and its relation to the African-Iberian plate convergence in the Late Cretaceous. Terra Nova, Volume 12, Number 3, June 2000, pp. 141-147(7). Robertson, A. H. F., Ustaomer, T., Pickett, E. A., Collins, A., Andrew, T. & Dixon, J. E. 2004. Testing models of Late Palaeozoic-early Mesozoic orogeny: support for an evolving one-Tethys model. Journal of the Geological Society, London,161, 501-511. Rosenbaum, G., Lister G. S. and Duboz C. 2002. Relative motions of Africa, Iberia and Europe during Alpine orogeny. Tectonophysics 359 (2002) 117–129. Scotese, R. C., Gahagan, L. & Larson, R. L., 1988. Plate tectonic reconstructions of the Cretaceous and Cenozoic ocean basins. Tectonophysics, 155, 27-48. Stampfli, G., Borel, G., Cavazza, W., Mosar, J., & Ziegler, P.A., 2001. (Editors): The Paleotectonic Atlas of the PeriTethyan Domain. Published by the European Geophysical Society. Stampfli, G.M., Borel, G.D., 2002. A plate tectonic model for the Paleozoic and Mesozoic constrained by dynamic plate boundaries and restored synthetic oceanic isochrons. Earth and Planetary Science Letters 196, 17– 33. Stampfli, G.M., Borel, G.D., 2003. A Revised Plate Tectonic Model for the Western Tethys from Paleozoic to Cretaceous. AAPG International Conference Barcelona, Spain September 21-24, 2003. Touir J. 1999. Sédimentologie, relation tectono-sédimentaire et diagenèse carbonate du Crétacé supérieur de Jebel M’rhila (Tunisie centrale), Thèse de Doctorat, Université de Tunis II. Turki, M.M. 1985. Polycinématique et contrôle sédimentaire associé sur la cicatrice Zaghouan-Nebhana. Témoignages de déformations synsédimentaires prétectogénétiques (Trias-Crétacé) en Tunisie. Thèse d’Etat, Faculté des Sci. de Tunisie. Revue des Sci. de la Terre. Vol. 7, 1988, Tunis. Vially, R., Letouzey, J., Benard, F., Haddadi, N., Desforges, H., Askri, H., & Boudjema, A., 1994. A basin inversion along the North African margin: The Saharan Atlas (Algeria), in Peri-Tethyan Platforms. Edited by F. Roure, 79-118, Technip, Paris. Vila, J.M., 1980. La chaîne alpine d’Algérie orientale et des confins algéro-tunisiens. Unpublished thesis, University of Paris VI, France, 665 p. (Unpubl.) Warme, J.E. 1988. Jurassic carbonate facies of the central and eastern High Atlas Rift, Morocco. In Jacobs Hager V.H eds. The Atlas system of Morocco. Springer Verlag. 169199. Zagrarni, M.F. 1999. Sédimentologie, stratigraphie séquentielle et diagenèse des facies du Crétacé supérieur du jebel Bireno. Paléogéographie des plate-formes carbonatées du Cénomanien-Coniacien en Tunisie centrale. Doctorat de Géologie, Fac. Sc. Tunis. Zargouni, F. 1985. Tectonique de l’Atlas méridional de Tunisie. Evolution géométrique et cinématique des structures en zone de cisaillement. Thèse ès Sci. Univ. de Strasbourg. Rev. Des Sci. De la Terre. Vol. 3. Zouaghi, T, Bédir, M, Inoubl, M. H. 2005. 2D Seismic interpretation of strike-slip faulting, salt tectonics, and Cretaceous unconformities, Atlas Mountains, central Tunisia. Journal of African Earth Sciences 43 (2005) 464–486 Zoback, M. L. 1994. Present day stress in Plate boundaries zones: Influence of relative motions and Plate geometry. Peri-Tethyan Platforms. Edited by François Roure.

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Proceedings of the IFP/PERI-TETHYS Research Conference held in Arles, France, 1993. Editions TECHNIP, pp. 121-128.

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In: Geomorphology and Plate Tectonics Editors: D. M. Ferrari, A. R. Guiseppi

ISBN: 978-1-60741-003-4 © 2009 Nova Science Publishers, Inc.

Short Communication A

3D MORPHOLOGY OF PHASE MICROSCOPIC OBJECTS BY THE DIGITAL HOLOGRAPHIC INTERFERENCE MICROSCOPY METHOD T.V. Tishko, D.N. Tishko and V.P. Titar Laboratory of Holography, Faculty of Radio Physics, Kharkov National University, Kharkiv, Ukraine

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ABSTRACT Combining the holographic methods with the methods for digital image processing has made it possible to develop the digital holographic interference microscope (DHIM) for real-time 3D imaging of phase microscopic objects and measurement of their morphological parameters. The instrument integrates holographic interference microscope with digital processing of interferograms. For the first time it has become possible to obtain optically 3D images of native cells. In this chapter we present result of DHIM application for experimental study of the 3D morphology of biological and technical phase microscopic objects. They are human blood erythrocytes and thin films. It is demonstrated that, in addition to hematological diseases, the diseases of various genesis and external factors serve as the reason for the morphological modification of blood erythrocytes. It is detected that morphologic modifications are nonspecific. It is proved that erythrocyte 3D morphology reflects the state of a living organism and the level of its biological response on different external factors influence. The proposed 3D model of erythrocyte makes it possible to quantitatively estimate the effect of morphological modifications of blood erythrocytes on their functionality with respect to oxygen transfer. It is demonstrated that the observed morphological modifications of erythrocytes lead to a significant decrease in the blood oxygen capacity and can serve as a reason for hypoxia. It is demonstrated that DHIM can also be successfully used for transparent thin films 3D visualization and quantitative investigation.

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T.V. Tishko, D.N. Tishko and V.P. Titar

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INTRODUCTION A lot of objects of wildlife and nonliving matter are microscopic objects. They are invisible for human eye. A. Levenguk was the first, who created a microscope. Since that time microscopes are used for investigation of microscopic objects. Most of microscopic objects are phase objects that do not change the intensity of the radiation transmitted through them and are inaccessible to direct observation by optical microscope. They are cells and tissues of human organism, thin films, etc. To observe such phase microscopic objects it is necessary to transform phase changes, which they cause in the light wave, into intensity changes. Special methods must be used for phase microscopic objects visualization. For the first time this problem was solved by F. Zernike [1].For the phase-contrast method and the phase-contrast microscope he won Nobel Prize in physics in 1953. But classical microscopy methods allow only two-dimensional visualization of phase microscopic objects, measurement of their morphological parameters is impossible. The interference contrast method allows quantitative measurements, but this method can be used only for thin films thickness measurement. So, the problem of 3D visualization of phase microscopic objects has not been solved in classical microscopy. Till recently, electron microscopy was the only method for the 3D imaging of microscopic objects. However, this high-resolution method necessities long preliminary treatment of the sample, which makes it impossible to study native living cells. In addition, such a treatment affects cells and the reliability of the results of electron microscopy can be debated. Improving resolution of electron microscopy D.Gabor proposed the method of holography (Nobel Prize in Physics in 1971) [2]. Though Gabor’s idea has not realized in microscopy, the advent and development of holography as the method for the detection and reconstruction of the wave phase and amplitude resulted in the appearance of holographic analogs of the classical microscope methods [3-6].The holographic analogs of classical methods exhibit several advantages. The development of computers and the methods for the digital data processing has led to a new stage in microscopy. The problem of 3D visualization of phase microscopic objects has been solved by combining the holographic methods with the methods for digital image processing. The first digital holographic interference microscope (DHIM), which allows the real-time 3D imaging of phase microscopic objects and the quantitative measurements of their morphological parameters, has been created at the Laboratory of Holography, Kharkov National University, Ukraine. The first 3D images of the native human blood erythrocytes were obtained using the microscope in [7].Due to the topicality of the problem, several digital holographic microscopes were proposed for the 3D visualization of phase microscopic objects [8, 9].

THEORETICAL PRINCIPLES AND DHIM EXPERIMENTAL LAYOUT The DHIM consists of three main units: holographic microinterferometer, digital video camera and computer. A He-Ne laser with a wavelength of 0.63 μ m serves as the radiation source. The interferograms of the microscopic objects under study, obtained using the holographic microinterferometer, are recorded by the digital camera. The digital interferograms are computer processed using the mathematical algorithms that makes it

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possible to reconstruct 3D images of microscopic objects and to measure their geometrical parameters. The optical layout of the holographic microinterferometer is shown in fig1.

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Figure 1. The DHIM optical layout.

The radiation of laser 1 is divided into two waves by semitransparent mirror 5: the object wave and the reference wave. The object wave passes through microscope objective 11 and is directed to photographic plate (hologram) 12. The reference wave passes through collimator 9 and also is directed to hologram 12. Mirrors 3 and 4 are introduced into the system to rotate the waves. The reference wave plays an auxiliary role in the system. It is needed for recording and reconstructing the object wave from the hologram. A hologram of the “empty” object wave is recorded on photographic plate 12 in the absence of the test specimen in front of the microscope objective. The developed and fixed hologram is returned to its original position. It is used as an optical element of the microscope. A special holder makes it possible to displace the hologram relative to its initial position. Hologram 12 is situated between objective 11 and eyepiece 13.Since an unfocused image is recorded on the hologram, such a placement of the hologram makes it possible to increase the field of view of the microscope because of the possibility of displacing the eyepiece in a plane orthogonal to the observation direction, and to carry out additional focusing over the depth of the observed scene. The test specimen is placed in front of the microscope objective. When the “empty” object wave, reconstructed from the hologram by means of the reference wave, and a perturbed object wave, transmitted through the test specimen, propagate simultaneously, their interference pattern, i.e. interferogram, can be observed by means of eyepiece 13. So, the interferogram is result of interference of two object waves, passing the same path in different moments of time. The hologram of the “empty” object wave plays the role of the second shoulder of an interferometer. The necessary period of the background interference fringes is formed by

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shifting the hologram from its initial position by means of the micrometer screws of the holder. The quality and contrast of the hologram and of the interferogram are determined by such a quantity as the modulation depth of the interference pattern, which is maximal when the interfering waves have identical intensities and polarizations. Polarizers 6, 7 and 8 are introduced into the system to equalize the intensities and polarizations of the interfering waves. Interferograms of the microscopic objects being investigated are recorded by means of digital video camera 14. The recorded interferograms are transferred to a computer for further processing. A 40x0.65 objective and 10X eyepiece are used in the microscope. The hologram was recorded on PFG-03 plate. Developer GP-2 was used for processing the hologram. Phase objects do not change the intensity of the wave passed through them and cause only phase changes in the wave. The interference fringe shifts on an interferogram of a phase microscopic object are caused by the phase increment of the transmitted wave through the entire thickness of the object,

ϕ ( x, y ) =

2π

λ

z2

⋅ ∫ n( x, y, z ) ⋅ dz

(1)

z1

where Δn (x, y, z) is the difference of the refractive indices of the object and the ambient medium. Therefore, the interferogram makes it possible to see the phase profile of the object. If the object has a homogeneous refractive-index distribution, i.e. Δn = const, we get

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ϕ ( x, y ) =

2π

λ

⋅ n ⋅ t ( x, y )

(2)

where t ( x, y ) = z2 − z1 is the thickness of the object at a point (x,y) . From this,

t ( x, y ) = ϕ ( x, y ) ⋅

λ 2π ⋅ n

(3)

In the method of interferometry in fringes of finite width [6] the phase increment equals

ϕ ( x, y ) =

2π ⋅ h( x ', y ') T

(4)

where h( x ', y ') is the deviation of the interference fringe from its initial direction on the inteferogram of the microscopic object, and T is the period of the system of interference fringes. So

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

3D Morphology of Phase Microscopic Objects

t ( x, y ) =

h( x ', y ') ⋅ λ T ⋅ Δn

349 (5)

Measurement of h( x ', y ') and T on the interferogram of a microscopic object makes it possible to determine the thickness of the microscopic object in every point, reconstruct its 3D image by computer interferogram processing and perform necessary measurement.

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DHIM STUDY OF THE 3D MORPHOLOGY OF BLOOD ERYTHROCYTES The study of the interaction of a living organism with the environment at a cellular level is of great scientific interest. A cell is a unit of a living organism that reflects and determines the status and functioning of the biological system as a whole. A number of papers have appeared in recent years in which it was established that the main target of the action of various physical and chemical factors of the environment, as well as of internal pathologies and even of the mental states of living organisms are the cellular plasma membranes. The variation of the elastic properties of the cellular membranes under the action of various effects must unavoidably show up in a change in shape of the cells. The blood cells are of special interest. Blood unites the operation and functioning of all the organs of the living organism. Moreover, an erythrocyte is available for observation as a separate cell of a living organism. The blood erythrocytes are the cells whose main function is the oxygen transport from lungs to tissues and carbon dioxide transport to lungs. In addition, erythrocytes take part in the processes related to maintaining of the blood homeostasis at the organism level. An erythrocyte is a cell without nucleus, and the content of protein hemoglobin in it is 98 %. For the optimal functioning, the functional activity of hemoglobin must be maintained and the optimal 3D shape of erythrocyte must be realized. The erythrocyte shape must correspond to the maximum surface at the given volume and must ensure deformations providing the erythrocyte motion along thin capillaries. These conditions are satisfied for a biconcave disk shape, which is considered as the medical normal shape. The first image of erythrocyte as a biconcave disk was obtained using electron microscopy in [10]. Then, this result has been confirmed. It is commonly accepted that the fraction of the biconcave erythrocytes in the blood of healthy patients ranges from 60 to 97%. The results of electron microscopy show that, in addition to the hematological diseases, the diseases of various genesises can be the reason for modifications of the 3D shape of erythrocytes [11]. This made it possible to formulate the concept of the erythrocyte pathomorphosis. However, this concept is under question, since the morphological modifications observed using electron microscopy can be caused by various effects related to the sample preparation. Human blood erythrocytes, like other cells of a living organism, are phase microscopic objects. Therefore the problem of studying the morphology of erythrocytes involves the problem of 3D visualization of phase microscopic objects and of measuring their morphological parameters. Human erythrocytes are microscopic objects with a size of 7-8 μ m and a maximum thickness of about 2 μ m. Each one is a microscopic object with a low optical density and homogeneous refractive-index distribution, transparent for radiation from a He-Ne laser. The

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optical homogeneity of the erythrocytes makes it possible to use Equation (5) to compute the thickness of the erythrocytes at various points and reconstruct their 3D images. Equation (5) includes the quantity Δn , which equals the refractive-index difference of the microscopic objects and the ambient medium. The untreated dry blood smears on glass substrates were used in experiment. So, Δn equals the refractive-index difference of blood erythrocytes and air. The refractive index of blood was determined by means of an Abbe refractometer using a He-Ne laser and equals 1.352. So, Δn = 0.352. Figure 2 shows interferograms of individual erythrocytes and 3D images of erythrocytes reconstructed from the interferograms obtained using the DHIM.

Figure 2. Interferograms of individual erythrocytes (at the left) andreconstructed 3D images of erythrocytes (at the right).

Figure 3 shows reconstructed 3D image of a fragment of the blood smear. One can see the direction of blood smearing. We have determined three main morphological types of erythrocytes: biconcave disk, flat disk, and spherocytes [12]. These morphological types and their variants were detected in the native blood smears. To characterize the morphological type, a sphericity coefficient k is introduced as a ratio of the erythrocyte thickness at the center to the thickness at half radius (fig. 4). For the biconcave erythrocytes, flat disks, and spherocytes, the sphericity coefficient is less than unity, about unity, and greater than unity, respectively. The sphericity coefficient is measured upon the computer processing of the DHIM erythrocyte interferograms. Figure 5

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demonstrated the 3D images of the three main morphological types and their sphericity coefficients. The results obtained show that the morphological modifications of erythrocytes, induced by various pathologies and external factors, correspond to an increase in the sphericity coefficient. Figure 6 shows the fragment of the native smears of blood of a healthy man aged 56 (a) and a diseased woman aged 23 (b) [12]. It is seen that the biconcave erythrocytes dominate in the blood smear of the healthy patient. The fragment of the blood smear of the woman contains flat disks and spherocyte. The analysis of the blood smears of Ukrainians (control patient and patient with various non hematological diseases) shows that single-type erythrocytes (flat disks) dominate in 80% of blood smears [13]. The reason for such morphological modifications needs to be further studied. The morphological modifications related to a decrease in the erythrocyte surface area cause a decrease in the functionality with respect to the oxygen supply of tissues and organs.

Figure 3. 3D image of the fragment of the blood smear.

A 3D model of erythrocyte is proposed to quantitatively estimate the effect of morphological modifications of blood erythrocytes on their functionality with respect to the oxygen transfer [14]. The total surface area of all the blood erythrocytes is equal to the product of the number of erythrocytes in blood and the surface of a single erythrocyte. This quantity determines the oxygen capacity of blood. Evidently, the oxygen capacity depends on both the number of erythrocytes in blood and the erythrocytes surface area.

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Figure 4. Determination of the sphericity coefficient k; dc - thickness at the center; dr - thickness at a half of radius.

Figure 5. Three main morphological types of erythrocytes: biconcave (a), flat (b), and spherical (c) and their sphericity coefficients.

A variation in the erythrocyte morphology (the transformation of medically normal biconcave disks to flat disks) under the given erythrocyte volume leads to a decrease in the total surface area of the blood erythrocytes by a factor of almost 1.5. On the assumption that

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the erythrocytes functionality with respect to the oxygen transport is linearly related to the surface area, we conclude that the above morphological modifications result in a decrease in the functionality with respect to the oxygen transport by a factor 1.5. This is equivalent to the corresponding decrease in the number of normal (biconcave) erythrocytes in blood (i.e. a decrease in the oxygen capacity of blood by a factor of 1.5). A decrease in the oxygen capacity of blood causes hypoxia (the state that emerges upon the insufficient oxygen supply of the organism tissues and organs). In the medical literature, the blood hypoxia is only related to a decrease in the erythrocytes mass and the effect of the morphological modification on hypoxia is not considered. .Apparently, this is due to the absence of the technical means for the corresponding measurement. The above quantitative estimates prove that the modification of the erythrocyte shape at the constant erythrocyte volume and the normal hemoglobin content is equivalent to a decrease in the oxygen capacity of blood that corresponds to a loss of one third of the erythrocytes (moderate hemorrhage). The hypoxia caused by various reasons (including a perturbation of the erythrocyte morphology) induces reactions aimed at maintaining homeostasis. If the adaptive response is insufficient, functional damages and structural changes are initiated. Lately ozone therapy is used in medical practice for normalization of supplying organs and tissues of an organism with oxygen. In our case ozone therapy is used for patient with neurosensor hardness of hearing.

Figure 6. 3D images of the fragments of blood smears and the mean sphericity coefficients: (a) health patient (ks = 0.35) and (b) diseased patient (ks = 0.96).

We investigated 60 patients (men and women) with neusensor hardness of hearing of different genesis [15, 16]. The ages of patients are from 18 to 67. According to the modern understanding the problem, the main reason of the neusosensor hardness of hearing is deficiency of oxygen on any level of a hearing sensor with posterior negative influence on the functions of the hearing system. Untreated blood specimens were studied before and just after injections of ozonized physiological solution. All patients passed the audio testing after the course of ozone therapy. In all cases the positive medical effect was achieved. Investigation of 3D erythrocytes morphology of the patients using DHIM has shown that erythrocytes of all patients before treatment had the flat disk shape. After the injections of the ozonized physiological solution normalization of erythrocyte shape was observed. Figure 7 shows the

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T.V. Tishko, D.N. Tishko and V.P. Titar

results of ozone therapy influence on blood erythrocytes of a patient. Such results ware obtained for all patients.

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Figure 7. 3D images of fragments of blood smears of a patient before (a) and just after (b) injection of ozonised physiological solution.

These experiments have shown that flat disk shape of blood erythrocytes, which does not corresponds to the norm, is the main reason of oxygen deficiency, which causes neurosensor hardness of hearing. Injection of ozonized physiological solution resulted in normalization of erythrocyte morphology and the positive medical effect, because the functional possibilities of blood erythrocytes have increased. Of course, the lack of oxygen in tissues caused by erythrocytes modifications affect negatively on a whole organism and can be the reason of different pathologies. It is necessary to investigate the reason of such morphological modifications and the way of treatment. The DHIM experimental study of the 3D morphology of human blood erythrocytes has shown that the blood erythrocytes exhibit morphological modifications caused by hematological disease as well as the pathologies of various genesis and external factors. These unspecific modifications correspond to an increase in the erythrocyte sphericity coefficient. Such morphological modifications of erythrocytes can be a reason for hypoxia and, hence, functional and structural changes of organism.

DHIM STUDY OF THIN FILMS Lately the scientific and technical direction connected with thin film production is extensively developing. In the process of thin film deposition there is the necessity of the thin films morphology visual investigation and measurement of their thicknesses. Optical microscopes are widely used for such investigation. But they allow only 2D imaging, quantitative measurements are impossible. Application of microinterferometers has some advantages due to the possibility of coating thickness measurements. High accuracy of thickness measurement has been achieved for optically nontransparent coatings. But the known optical microinterferometers do not make it possible to obtain good results for transparent thin films (0.1-0.5 μ m) on transparent substrates. Till now the electron

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microscopy method was the single method for thin film morphology investigation. But this method does not make it possible to carry out quantitative measurements. So, the problem of thin transparent films investigation has not been solved. Thin films also are phase microscopic objects. That makes it possible to use the DHIM for thin films investigation. In this chapter we present our pioneer results of application the DHIM for investigation of thin films morphology investigation. Production of protective coating deposited on polymeric material surfaces is of great interest. Polymer goods with different coatings are used as functional elements in electronic equipment production, as units of aviation and space apparatus. Coatings for protection of plastic optical material are of wide application. Lenses made of such materials, along with well known advantages, shortcomings such as hyper plasticity, and a low value of hardness. That’s why plastic lenses are used together with optical transparent coatings, which contain strengthening layers. Using the coatings, it is possible to improve important costumer qualities of lenses, such as dirt repellent, anti-weeping and hydrophobic properties, abrasive wear firmness.

Figure 8. The fragment of the interferogram of the AlN film edge (at the top) and 3D image of the fragment (at the foot).

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Now application of alternative energy sources and improvement of their working characteristics are of great interest. Photoelectric transformers are used in solar batteries for energy transformation. Fresnel lenses made of acrylic are used in the devices. But under influence of environment, especially solar radiation, acrylic loses its optical properties. High transparence in the optical range, high firmless and chemical inertness makes AlN the perspective chemical compound for use on the polymer goods which are used for operation in the conditions of environment influence, especially under ultraviolet radiation influence. The technology of deposition of AlN coating on acryl substrates by vacuum-arc method is working out in the National Scientific Center “Kharkov Institute of Physics and Technology”. We used such thin AlN coatings on acrylic substrates as the objects under study in our experiments. Figure 8 shows a fragment of an interferogram of the AlN film on the acrylic substrate (a) and the reconstructed 3D image of the fragment. The thickness of the film is about 0.58 μ m.

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Figure 9 shows 3D image of the AlN film on acrylic substrate after damaging doze of ultraviolet radiation influence. The thickness of the film is about 0.1 μ m.

Figure 9. 3D image of the fragment of the AlN film on an acrylic substrate after influence of ultraviolet radiation.

One can see that after radiation influence the surface of the film is damaged. The crack is not only in the coating, but penetrates into the substrate. So, the DHIM can be successfully used for transparent thin films morphology investigation. It combines the possibility of a microscope and interferometer. One can obtain 3D image of a film surface and to measure its thickness at any point.

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CONCLUSION The digital holographic interference microscope (DHIM) makes it possible to obtain 3D images of phase microscopic objects and to measure their morphological parameters. DHIM was used for experimental study the 3D morphology of biological and technical phase microscopic objects. 3D morphology study of blood erythrocytes has been discovered that, in addition to hematological diseases, the diseases of various genesis and external factors served as the reason for the morphological modification of blood erythrocytes. The morphologic modifications are nonspecific. It has been proved that 3D erythrocyte morphology reflected the state of a living organism and the level of its biological response on different external factors influence. It has been demonstrated that the observed morphological modifications of erythrocytes lead to a significant decrease in the blood oxygen capacity and can serve as a reason for hypoxia. It has been shown that DHIM can be successfully used for thin films morphology investigation. DHIM use makes it possible to visualize the surface of a thin film and to measure its thickness, dimensions of film defects, roughness , etc.

REFERENCES [1]

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[2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16]

Franson M. Phase-Contrast and Interference Microscope; Gosizdat Fiz.-Mat.Lit., Moscow, Ru, 1960. Gabor D. J. Nature.1948, vol.161, 777. Safronov G. S.; Tishko T. V. Ukrainsk. Fizich. Zh.1985, vol.30, 333-337. Safronov G. S.; Tishko T. V. Ukrainsk. Fizich. Zh.1985, vol.30, 994-997. Safronov G. S.; Tishko T. V. Prib. Tech. Eksp.1987, vol.2, 249. Tishko T. V.; Titar V. P.; Tishko D. N. J .Opt. Technol. 2005, vol.72, №2, 203-209. Tishko T. V.; Titar V. P.; Panfilov D. A.; Tishko D. N. Biol. Vestnik.1998, vol.2, № 1, 107-111. Marquet P.; Rappaz B.; Magistretti P. J.;et al. Opt. Lett.2005, vol.30, 468-472. Popescu G.; Ikeda T.; Best C. A. J. Biomed. Opt. 2005, vol.10, 503-508. Salsbury A. J.; Clarke J. J. Clin .Pathol.1967, vol.20, 503-508. Novitsky V.V.; Ryazantseva N. V.; et al. Atlas. Clinical Erythrocyte Pathomorphosis; St.Petersburg Univ., St. Petersburg, Ru., 2003. Tishko T. V.; Titar V. P.; Tishko D. N. Vestn. Khark. Nats.Univ. Ser.Radiofiz.Electron. 2006, vol.712, 53-56. Novitsky V.V.; Ryazantseva N.V.; Tishko T.V.; Titar V.P.; Tishko D.N.; et al. Theory and Practice of Erythrocyte Microscopy; Pechat. Manufact., Tomsk, Ru, 2008. Tishko T. V.; Titar V. P.; Tishko D. N.; Nosov K. V. Las. Phys.2008, vol.18, № 4, 1-5. Tishko T. V.; Titar V. P.; Barkhotkina T. M.; et al. Vestnik Khark. Univ. Ser. Biofiz. Vestnik. 2000, vol. 497, 103-111. Tishko T. V.; Titar V. P.; Barkhotkina T. M.; Tishko D. N. Proc. SPIE, vol. 5582, 119127.

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In: Geomorphology and Plate Tectonics Editors: D. M. Ferrari, A. R. Guiseppi

ISBN: 978-1-60741-003-4 © 2009 Nova Science Publishers, Inc.

Short Communication B

TECTONIC CONTROL ON THE EVOLUTION OF THE MIDDLE TRIASSIC PLATFORMS IN THE ALPINE-CARPATHIAN-DINARIC REGION (DIFFERENCES IN THE EVOLUTION OF TWO OPPOSITE SHELVES OF THE NEOTETHYS OCEAN) Felicitász Velledits* Volterra Bt. Dunakeszi, Andrássy, Hungary

ABSTRACT

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Based on the Middle Triassic evolution of the carbonate platforms of the AlpineCarpathian-Dinaric region two different types can be distinguished. The first is characterized by Middle-Upper Triassic terrestrial sediments together with volcanites. They suffered repeated uplift in the Anisian-Carnian: 1. Piz da Peres Conglomerate, (Bithynian); 2. Voltago Conglomerate, (Early Pelsonian); 3. Richthofen Conglomerate (Illyrian: Trinodosus zone/Trinodosus subzone); 4. Ugovizza Breccia 2 (upper Illyrian: Avisianum subzone); 5. Conglomerate and sandstone of Fassanian age; 6. Bauxite: Upper Ladinian-Carnian. The uplift was accompanied by volcanic activity, and followed by rapid subsidence. Carbonate platforms belonging to the first type can be found in the Dolomites, Carnic Alps, Julian Alps, South Karavank Mts., Bükk Mts., and External Dinarides. The age of the uplift is younger and younger as we proceed from the Dolomites towards the Carnic and Julian Alps, Karavanks, External Dinarids. On the southern shelf the platforms are small, and the shape is more or less round and the basins cover a much bigger area than platforms. The second carbonate platform type is characterized by the lack of terrestrial sediments and volcanics. Such platforms can be found in the Northern Calcareous Alps (NCA), the Western Carpathians (WNC) and the Drina Ivanjica Element of the Internal Dinarids. The ages of the drownings: 1. Balatonicus zone: Balatonicus subzone, 2.

*

Correspondence to: Volterra Bt. 2120 Dunakeszi, Andrássy Gy. u. 6. Hungary, [email protected]

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Felicitász Velledits boundary between the Balatonicus and Trinodosus zones: Binodosus-Trinodosus subzones, 3. Reitzi zone: Avisianum subzone. The age of many terrestrial sediments, i.e., uplifts, coincide with that of the drowning events. On the northern shelf the platforms are big and have long, elongated shapes; the platforms cover a much bigger area than the basins. The carbonate platforms of the first type were deposited in the Triassic on the southern shelf, and the second type on the northern shelf of the ocean, the remnants of which build up the Dinaride Ophiolite Belt. The asymmetric evolution of the two shelves, and the younger and younger age of the uplift, and accompanying volcanic activity can be explained by mantle plume activity.

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INTRODUCTION The basement of the Pannonian basin shows a mosaic pattern made up of allochthonous terranes derived from different parts of the Tethyan realm. On the NE part of the large, composite Pelso Megaunit (Kovács 1982, Tollmann 1987, Haas ed. 2001) on the opposite sides of the Darno fault zone, there are two mountains: Bükk Mts. and Aggtelek-Rudabánya Mts. The Triassic sections of the Bükk Mts. were deposited on the southern shelf of the opening Neotethys Ocean, whereas formations building up the Aggtelek-Rudabánya Mts. were deposited on the northern shelf. Due to the Neogene tectonic movement, Triassic carbonate platforms originated from the two opposite shelves are today situated close to each other on the two opposite sites of the Darnó fault zone (Fig.1b). The Carboniferous–Late Triassic sequence of the Bükk Mountains shows striking similarities to that of the Jadar and Sana–Una units of the Dinarides (Protić et al. 2000). According to the paleogeographic reconstruction of Kovács (1984), Tollmann (1987) and Haas (2001) in the Triassic, the Bükk Mts. were situated adjacent to the Julian Alps and the South Karavank Mts. and came into their present-day position during a several hundred km displacement along dextral strike slips (Middle Hungarian Lineament) only in the Late Oligocene–Early Miocene. Opposite to this the Triassic formations building up the AggtelekRudabánya Mts belong to the nappes of the Inner West Carpathians. In the Middle–Late Triassic, the West Carpathians together with the Northern Calcareous Alps were situated on the northern shelf of the opening Vardar–Meliata branch of the Neotethys (Kovács 1982, 1997, Tollmann 1987, Haas ed. 2001) ocean. Research began with the detailed study of the Triassic carbonate platforms of the Bükk Mts. and the Aggtelek-Rudabánya Mts. (Velledits 2006, Velledits et al. in prep). The comparison of the Middle-Upper Triassic successions of the two mountains shed light on the striking difference in the evolution of the two opposite shelves. Research was continued with the collection of excessive knowledge on the Middle Triassic development of the two opposite shelves partly by numerous site visits in the Dolomites, Southern Karavanks, Kamnik-Savinja Alps, Julian Alps, Dinarids, North Calcareous Alps and West Carpathians and partly from literature.

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Figure 1.a. Major geographic and geologic units of the Alpine-Carpathian-Dinarid regions. The numbers indicate the numbers of the Triassic sedimentary successions of the different units depicted on Fig 2a-b. Horizontal lines indicate platforms the sedimentary succession of which were deposited on the southern shelf, the vertical lines of those on the northern shelf. Modified and simplified after Kovács et al. (2000). 1.b. Simplified geologic map of Bükk Mts., Aggtelek Rudabánya Mts. and Darnó zone. Due to the Neogene tectonic movement Triassic carbonate platforms originated from the two opposite shelves. Bükk Mts. from the southern shelf (oblique lines), Aggtelek Rudabánya Mts. form the northern shelf (horizontal lines). They are today situated close to each other on the two opposite sites of the Darnó fault zone. Simplified after Kovács (1989).

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The aim of this chapter is to show the differences in the Middle Triassic evolution of the two opposite shelves, to show the effect of the rifting (mantle plume) on the platform evolution which support the correctness of the state-of-the-art asymmetric rifting model (Velledits 2006) as opposed to the formerly accepted symmetric model (Kovács 1982, Haas 2001). Opinions of the researchers vary as to whether there was a single ocean or more branches of the Neotethys Ocean. According to Karamata (2006) and Sudar et al. (in press) the Neotethys Ocean had more than one branch: Vardar-Meliata to the east, and the Dinarid Ophiolite Belt (DOB) to the west (Fig.1a). However according to Csontos et al. (2003) there was only one, and the western branch was overthrusted into its present day position only due to subsequent tectonic movement. Formerly Kovács (1992), and Haas (2001) used the name “Vardar-Meliata Ocean” for the western ending of the Neotethys Ocean around which the Alpine-Carpathian-Dinaric carbonate platforms developed, but more recently Sudar (in press) use the name “Vardar zone” for the eastern ophiolite belt, whereas now they call the western ophiolite belt the Dinaric Ophiolite Belt (DOB). See Fig.1a. This chapter will discuss the evolution of the platforms apart from the number of the branches of the Neotethys Ocean.

PLATFORM EVOLUTION IN THE TRIASSIC Taking into consideration the volcano-sedimentary succession, the subsidence/uplift history and the shape of the Triassic platforms in the Alpine-Carpathian-Dinaric region, two striking different platform types can be distinguished. The differences are as follows:

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1. Presence or Lack of Anisian/Ladinian Terrestrial Sediments and Volcanics In the Triassic sequences of the Dolomites, Carnic Alps, Julian Alps, South Karavank Mts., Bükk Mts., and External Dinarides, terrestrial sediments (alluvial fans, fluviatile conglomerates, lake marls) appear in the Anisian between the thick carbonate formations, indicating the updoming of these areas. These terrestrial sediments were frequently deposited with a significant discordance on Permian or Carboniferous beds (Placer & Car 1977, Fois & Jadoul 1983, Brandner 1984, Jadoul & Nicora 1986, Gianolla et al. 1998, Velledits 2004). The thickness of the conglomerate may reach as much as 500 m at some places (Čar & Skaberne 2003). Coevally with the terrestrial sediments, or following them, volcanites appear in these areas. Their thickness may reach several hundred meters locally. From the Dolomites, terrestrial sediments were described at three levels (Bechstädt & Brandner 1970; Assereto et al. 1977; De Zanche et al. 1992; De Zanche et al. 1993; Senowbari-Daryan et al. 1993; Gianolla et al. 1998). From the oldest to the youngest these are 1. Piz da Peres Conglomerate (Bithynian); 2. Voltago Conglomerate (Early Pelsonian,); 3. Richthofen Conglomerate (Illyrian, Trinososus zone/Trinodosus subzone). The most significant erosion occurred during the formation of the Richthofen Conglomerate, the base of which deeply cut the Anisian, Lower Triassic and Permian units. On the basis of the analysis of the pebbles of the Richthofen Conglomerate, Bechstädt & Brandner (1970) concluded that

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more than 400 m thick sediment was eroded at this time. 4. To the East of the Dolomites, in the Carnic Alps, Julian Alps and Karavanks, and in the neighborhood of Idrija (N Dinarides) a younger conglomerate level also appears in the upper Illyrian: Avisianum subzone: Ugovizza Breccia 2 (Fig.2a) (Farabegoli, Levanti (1982), Fois, Jadoul (1983), Jadoul, Nicora (1986), Farabegoli et al. 1985, Krainer, Lutz (1995). 5. In addition to this Mostler, Krainer (1994) describe a 40 m thick conglomerate and sandstone layer from the Lower Fassan. 6. From the External Dinarids from the Mt. Svilaja Balini et al. (2006), from the Lika Mts Trubelja (2003) describe bauxites together with volcanites that lie on the karst surface of the Ladinian limestones and are overlaid by Upper Triassic platform carbonates. If we consider the age of the terrestrial sediments it is conspicuous that the youngest of each unit appears later and later: in the Dolomites the age of the main terrestrial sediments is Upper Pelsonian/Lower Illyrian (Richthofen Cgm), in the Carnic Alps, Julian Alps and Karavanks, and in the neighborhood of Idrija upper Illyrian: Avisianum subzone (Ugovizza Breccia 2), in the Southern Karavanks Early Fassanian and further to the SE in the External Dinarids Upper Ladinian-Carnian. The Triassic sequences of the Northern Calcareous Alps (NCA), and Western Carpathians (WNC) and Drina Ivanjica Element of the Internal Dinarids show a quite different character. Terrestrial sediments and volcanics of considerable thickness are missing. Volcanites are present only as some cm or dm thick volcanic intercalations. Coeval with the Anisian terrestrial sediments of the above-mentioned areas, the platforms (or parts of the platforms) were drowned (Fig.2b). According to the paleogeographic model of Kovács (1982, 1997), Tollmann (1987), Dercourt et al. (2000), Ziegler & Stampfli (2001) and Haas (2001), areas with terrestrial sediments and volcanics (Dolomites, Carnic Alps, Julian Alps and Karavanks, Bükk Mts., External Dinarides) were deposited south of the opening Neotethys ocean. Despite this the NCA, the WNC, and the Drina Ivanjica Element (Internal Dinarids) were deposited on the northern shelf. Later in this chapter the first will be called southern shelf and the latter northern shelf. If we compare the age of the terrestrial sediments (Fig.2a ) of the southern shelf with the age of the drowning event on the northern shelves (Fig.2b ), we can conclude that many episodes of uplift on the southern margin coincide with episodes of drowning in the north. This leads to the question whether every terrestrial sediment refers to tectonic activity, i.e., the uplift of the crust, or whether some of them are controlled by sea level change? Rüffer & Zühlke (1995) and Zühlke (2000) have presented some results by simple numerical basin modelling with respect to subsidence/uplift rates and primary control by sealevel changes or subsidence/uplift. According to them, sequence boundaries in large parts of the Southern Alps (Eastern Dolomites, Lombardy), in the European epicontinental seas (SWGermany), in the Arctic Sea (Barents Sea, Canadian Arctic), and in China correlate with each other. Numerical modelling for the Dolomites (Rüffer & Zühlke (1995) and Zühlke (2000)) indicates that the origins of the Piz da Peres Conglomerate and Voltago Conglomerate in large areas of the eastern Dolomites were induced by sea-level changes, whereas the Richthofen Conglomerate of the western Dolomites and the Voltago Conglomerate in the Southern Dolomites were primarily controlled by tectonics.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers, Incorporated, 2009.

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Figure 2. a. Middle Triassic successions of the different tectonical units of the southern shelf. The circled numbers in each column heading refer to the numbers in Fig.1. where they indicate the present geographical position of the unit. The arrows depict periods with high subsidence rate.

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Figure 2.b. Middle Triassic successions of the tectonically different units of the northern shelf and the Transdanubian Range, which shows transition between the two shelves types. The numbers in the rectangles in the heading of every column refer to the number in the Fig.1a. depicting the present geographical position of the unit. Arrows indicate drowning events. Column 6: based on Vörös et al. (2003) 7. based on Bechstädt et al. (1978) and Brandner and Resch (1981), 8: Piller et al. (2004), 9: Velledits et al. (in prep), 10: Dulić et al. (2006).

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On the northern shelf platform drownings and neptunian dykes give information about the tectonically active periods. On the southern shelf the age of the uplifts i.e the age of the terrestrial sediments indicates the tectonically active periods. Taking into consideration the results of Rüffer & Zühlke (1995) and Zühlke (2000) the age of the drowning events, and the age of the neptunian dykes the following periods can be regarded as tectonically active periods: 1. 2. 3. 4. 5.

Balatonicus zone: Balatonicus subzone, Pelsonian-Illyrian boundary: Binodosus-Trinodosus subzones, Reitzi zone: Avisianum subzone, Upper Ladinian-Carnian. Based on the results of Mostler and Krainer (1994) a fifth period can be assumed its age was determined as Fassan according the earlier stratigraphic subdivision.

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2. Subsidence/Uplift History In the subsidence history of the Dolomites and the Bükk Mts. during Anisian to Carnian three distinctive periods can be distinguished: uplift in the Middle-Upper Anisian, rapid subsidence in the Late Anisian-Early Ladinian, and slow subsidence from the Middle Ladinian onward. According to Maurer (2000) after the Anisian uplift the rate of subsidence considerably accelerated in the Late Illyrian-Early Ladinian. He estimates 200 Bubnoffs (m/Ma) for this period. According to him the subsidence was 600-700m in the western Dolomites, whereas in the central Dolomites and Carnia it was higher, 900-1050m. In the Bükk Mts. we do not have such an exact age determination, but the tendency of the subsidence is quite similar. After the Anisian uplift the subsidence reached 200–300 m/Ma in the Early Ladinian. The rapid subsidence stopped in the Ladinian in both areas. Bosellini (1991, 1997) has first pointed out that the rapid subsidence stopped in the Late Ladinian over almost the whole Dolomite Region. According to Maurer (2000) the subsidence slowed down in the Gredleri and Archelaus zones, reaching only 50 Bubnoffs. In the Bükk Mts. the rapid subsidence slowed down at the end of Fassanian (Velledits 2006). To the east of the Dolomites in the Carnic Alps (Farabegoli, Levanti 1982), in the Julian Alps (Farabegoli et al. 1985) Idrija area (Placer, Čar 1977) the uplift happened in the Illyrian (Avisianum subzone) as well. Terrestrial sediments appeared together with volcanics, and were followed by deep water sediments (Buchenstein Lmst). In the External Dinarides Ladinian-Carnian bauxites appear together with volcanic rocks, but they are covered by shallow water carbonates. Consequently, the subsidence after the uplift was not rapid. But we have to assume rapid subsidence before the base of the deep water cherty limestone i.e. between Late Illyrian-Early Longobardian. The subsidence history of the platforms deposited on the northern shelf is different during the Middle Triassic. Instead of uplift, the platforms, or parts of the platforms were subsided (Fig.2b ) due to tectonic activity. In the Northern Calcareous Alps, due to the “Reifling event” a part of the Steinalm platform was drowned during the Pelsonian (Schlager & Schöllnberger 1975, Lein 1987). Due to the block faulting and rapid deepening of some parts of the Steinalm platform, platforms (Wetterstein Formation) and basins were formed. The basins

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can be subdivided into the Reifling/Partnach basins (intraplatform basins) and the Hallstatt (s.l.) deeper shelf, the latter one bordered the opening Neotethys Ocean (Mandl 2000). In the WNC the situation is similar. At the beginning of the Illyrian, but locally already in the Late Pelsonian, the first sediments of basin facies appear in the Silica and Torna Nappes of the Western Carpathians (Kovács 1984, Mello et al. 1997, Velledits et al. in prep), indicating the first significant differentiation of the crust. In the Silica Nappe, platforms (Wetterstein Limestone) and intraplatform basins (Reifling Limestone, Nádaska Limestone, Schreyeralm Limestone) were formed. The platform edge bordering the opening ocean was drown in the Pelsonian, the sedimentation remained pelagic from the Pelsonian onward (Bódva unit=Hallstatt facies). In the Drina Ivanjica Terrene (Inner Dinaides) the Han Bulog Limestone represents the first deep water sediments above the Pelsonian platform carbonates. The base of the Han Bulog Limestone is Binodosus/Trinososus subzone (Sudar, Budurov 1983). On the northern shelf the following drowning events can be detected 1. Bithynian/Pelsonian boundary; in the Transdanubian range (Vörös et al. 2003), in the Tirolicum (Tatzreiter 2001)), 2, around the boundary between the Binodosus/Trinodosus subzones; Transdanubian range (Vörös et al. 2003), Tirolicum (Tatzreiter 2001), Juvavicum (Piller et al. 2004), Aggtelek (Velledits et al in prep), Internal Dinarids (Sudar, Budurov 1983), 3. in the Avisianum subzone; Transdanubian range (Vörös et al. 2003).

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3. Geometry of the Platforms Striking differences can be seen in the geometry of the Late Illyrian-Ladinian carbonate platforms of the two opposite shelves. On the southern shelf (Dolomites, Bükk Mts.) small (425km in diameter), more or less round island platforms can be found (see Fig.3a for the Dolomites, and Velledits 2006/Fig.9 for the Bükk Mts.) On the northern shelf the platforms have long, elongated shape. For an example see the Ladinian-Cordevolian Wetterstein platform from the Western Carpathians (Fig.3b), the size of which is today 48x8-12 km. In the first case the majority of the area is covered by basins, the platforms emerge really as islands. As oppose to this, in the second case the platforms cover huge areas, whereas the small basins appear today only on the edges of the platforms. The different geometry of the platforms was probably controlled by different stress field. Remark: it must be noted that the Middle Triassic evolution of the Transdanubian Range shows partly similar features to the southern shelf like presents of volcanic rocks of significant thickness partly similar features to the northern shelf like the lack of terrestrial sediments and the shape of the platforms.

CONSEQUENCES FOR PLATE TECTONICS The northern and southern rifted-margins of Neotethys had very different stratigraphic and subsidence records during the Middle Triassic. The geometry of the platforms also differed considerably. Velledits 2004, 2006 justified that the Middle–Upper Triassic sequences of the Alpine–Carpathian-Dinaric region follow the asymmetric rifting model of

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Wernicke (1985) and Dixon et al. (1989). The evolution of the southern shelf follows the evolution of the updoming part, the sedimentary successions deposited northern shelf follows the evolution of the break-away part of a rifting ocean. The evolution of these two shelves and the oceanic remnants can be easily correlated (see Velledits 2006). The appearance of the terrestrial sediments between thick carbonate sequences, their consistently younger and younger age, the coeval accompanying volcanics and the succeeding rapid subsidence can be well explained by the mantle plume activity on rifting areas. White and Lovell (1997) investigated the effect of mantle plumes on the sedimentary record, or in other words, they considered the sedimentary record as proxy for plume activity. They justified that the discrete episodes of sand deposition in the Paleogene of the North Sea reflect pulses in the early Iceland plume. The study of the sedimentary record indicates that underplating takes place episodically, if not periodically, at intervals of the order of a million years or more. They also describe, that pulses of surface uplift are shortly followed with subsidence, which may be explained by invoking rapid crystallization of the underplate. The Iceland plume was accompanied with widespread magmatism.

Figure 3.a. Platforms and basins of the Dolomites in the Early Ladinian. Modified after Bosellini (1991).

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers, Incorporated, 2009.

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Figure 3.b. One carbonate platform from the Western Carpathian and the bordering basins. Simplified after Less. Gy., Mello, J. (2004)

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Anisian-Ladinian terrestrial sediments repeatedly occur in the Triassic sedimentary record SW from the axis of the DOB. Because these terrestrial episodes coincide with the drowning events of the carbonate platform on the northern shelf, sea level change can not be the main control factor. The accompanying magmatic activity and the following rapid subsidence also refers to mantle plume activity as the main control factor. According to Pamić and Balen (2005) volcanic rocks of the DOB were spatially and genetically related to the Triassic rifting, and their major and trace elements content indicate an upper mantle origin. The younger and younger age of the terrestrial sediments can be best explained by the horizontal movement of the crust above the repeatedly upwelling mantle plume. This fact is also confirmed by the rapid subsidence following the uplift of the crust.

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CONCLUSION 1. Based on the Middle Triassic volcano-sedimentary successions in the AlpineCarpathian-Dinaridic region, two different platform evolutions can be distinguished. The volcano-sedimentary successions deposited on the southern shelf are characterized by the repeated appearance of terrestrial sediments and volcanites, which are followed by rapid subsidence. The platforms are small; the shape of the platforms is round. One the other hand, sediments deposited on the northern shelf are characterized by the lack of terrestrial sediments and volcanites. These platforms or parts of platforms were episodically drowned. The extension of the platforms is huge; the shape is elongated. 2. Many episodes of uplift on the southern shelf coincide with episodes of drowning on the northern shelf. 3. The age of the youngest uplift of every unit became younger as we proceeded from the Dolomites to the Carnic Alps-Julian Alps-External Dinarids. 4. The repeated appearance of the terrestrial sediments together with the volcanites and the following rapid subsidence on the southern shelf, and the coeval drowning events on the northern shelf can not be explained by sea level change. The reason must be in a process in the inner part of the Earth. The most probable mechanism for the asymmetric evolution of the two opposite shelves can be the mantle plume activity. The appearance of younger and younger terrestrial sediments can be explained by the horizontal movement of the crust above the mantle plume.

AREAS WHICH NEED TO BE EXPLORED The most authentic explanation for the asymmetric evolution of the Triassic shelves bordering the Neotethys ocean is the mantle plume activity, which is characteristic of a rifting area. To understand the effect of the mantle plume on the sedimentation on the surface of the crust is only possible if we understand the Middle Triassic rifting of the Neotethys ocean.

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There is no recent widely accepted model for rifting. Detailed studies in the latest years carried out on numerous recent and fossil rifts seem to justify the simple shear (asymmetric rifting) model of Wernicke (1981, 1985) and Dixon et al. (1989). As opposed to former (symmetric) rifting models (McKenzie 1978), this model states that the evolution of the two opposite shelves, bordering the opening ocean, is asymmetric during the rifting in the sense of topography and volcanism. In a rifting area, episodic and repeated magmatic underplating associated with mantle plume activity is the most probable mechanism for regional surface uplift and denudation. The understanding of the Triassic rifting of the Neotethys requires broadly based interdisciplinary studies, to understand the complex interaction between processes in the Earth’s asthenosphere, lithosphere, and the sedimentation on the surface of the crust. Therefore, to justify or reject the asymmetric rifting model would require a multidisciplinary project, in which the interactions between tectonics and surface processes would be investigated with both the classical (sedimentology, paleontology, biostratigraphy) and the most advanced (absolute age determination by U/Pb, numerical forward modeling, subsidence analyses) methods of basin analysis. In the first step a data base concerning the exact age of every uplift and drowning would be necessary. At present, data are especially scanty from the South-Eastern part of the Dinarids. Data must be collected from the Hellenides as well. These should be completed with the geochemical analyses of the volcanites. Subsidence/uplift geohistory plots should be constructed for both margins. The subsidence histories of the margins of the Triassic Neotethys must be compared with predictions from thermo-mechanical models that consider the additional heating by magma intrusion. Comparison should be made with youthful margins, such as the Gulf of Aden and southern Red Sea which are distal and proximal to flood volcanic provinces. This interdisciplinary project would significantly contribute to the paleogeographical reconstructions of the Triassic

REFERENCES Assereto, R., Brusca, C., Gaetani M., Jadoul, F. (1977) The Pb-Zn mineralization in the Triassic of the Dolomites. Geological history and genetic interpretations. L’industria Mineria, 231, 1-34. Balini, M., Jurkovšek, B., Kolar-Jurkovšek, T. (2006) New Ladinian Ammonoids from Mt. Svilaja (External Dinarides, Croatia). Rivista Italiana de Paleontologis a Stratigrafia. 112/3, 383-395. Bechstädt, T., Brandner, R., Mostler, H., Schmidt, K. (1978) Aborted rifting in the Triassic of the Eastern and Southern Alps. N Jb Paläont Abh 156,157-178. Bechstädt, T., & Brandner, R., (1970) Das Anis zwischen St. Vigil und dem Höhlensteintal (Pragser- und Olanger Dolomite, Südtirol). – Festband Geol. Inst., 300-Jahr-Feier, Univ. Innsbruck, 9-103. Bosellini A (1991) Geology of the Dolomites. An introduction Dolomieu Conference on Carbonate Platforms and Dolomitisation Ortisei/St. Ulrich, Val Gardena/Grödental: 1-43 Bosellini A (1998) Geologie der Dolomiten. Bozen: Athesia. 1-192

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372

Felicitász Velledits

Brandner, R., Resch, W. (1981) Reef development in the Middle Triassic (Ladinian and Cordevolian) of the Northern Limestone Alps near Innsbruck, Austria. In: Toomey D.F. (eds): European fossil reef models. Soc Econom Paleont and Miner Spec Publ 33, 203231 Brandner, R. (1984) Meeresspiegelschwankungen und Tektonik in der Trias der NW-Tethys. Jb. Geol. B.-A., 126/4,435-475. Čar, J., Skaberne, D. (2003) Stopniški Konglomerati. Geologija, 46/1: 49-64. Csontos, L., Gerzina, N., Hrvatović, H., Schmid, S.M., Tomljenović, B. (2003). Structure of the Dinarides: a working model. Annales Universitatis Scientiarum Budapestinensis de Rolando Eötvös Nominatae. Sectio Geologica. 35, 143-145. De Zanche, V., Franzin, A., Giannola, P., Mietto, P., Siorpaes, C. (1992) The Piz da Peres section (Valdaora-Olang, Pusteria Valley, Italy). A reappraisal of the Anisian stratigraphy in the Dolomites. Eclogae geologicae Helvetiae, 85/1, 127-143. De Zanche, V., Giannola, P., Mietto, P., Siorpaes, C., Vai, P.R. (1993) Triassic sequence stratigraphy in the Dolomites (Italy): Memorie di Scienze Geologiche, 45, 1-27. Dercourt, J., Gaetani, M., Vrielynck, B., Barrier, E., Biju-Duval, B., Brunet, M.F., Cadet, J.P., Crasquin, S., Sandolescu, M. eds. (2000) Atlas Peri-Tethys, Palaeogeographical maps. CCGM/CGMW, 24 maps and explanatiry notes: I-XX, 1-269 Dixon, T.H., Ivins, E.R., Franklin, B.J. (1989) Topographic and volvanic asymmetry around the Red Sea: constraints on rift models. Tectonics, 8/6, 1193-1216 Dulić, I., Wagreich, M., Javanović, R. (2006) 1st International Workshop „Mesozoic Sediments of Carpatho-Balkanides and Dinarides”. Novisad. 1-70. Farabegoli, E., Jadoul, F., Martines, M. (1985) Stratigrafia e paleogeografia anisiche delle Alpi Giulie occidentali (Alpi Meridionali – Italia) Riv. It. Paleont. Strat., 91/2, 147-196. Farabegoli, E., Levanti, D. (1982) Triassic Stratigraphy and Microfacies of the Monte Pleros (Western Carnia, Italy). Facies 6, 37-58. Fois, E., Gaetani, M. (1984) The recovery of reef-building communities and the role of Cnidarians in carbonate sequences of the Middle Triassic (Anisian) in the Italien Dolomites. Palaeontogr Amer 54,191-200. Fois, E., Jadoul, F. (1983) La dorsale paleocarnica anisica de Pontebba. Riv. It. Paleont. Strat., 89, 3-30. Fülöp, J., Brezsnyánszky, K., Haas, J., (1987) The new map of basin basement of Hungary. Acta Geol. Hung 30, 3-20. Gianolla, P., De Zanche, V., Mietto, P. (1998) Triassic sequence Stratigraphy in the Southern Alps (Northern Italy): definition of sequences and basin evolution In: Mesozoic and Cenozoic Sequence Stratigraphy of European Basins, Tulsa: SEPM Spec. Pub., 60: 719747. Haas, J. (ed) Hámor, G., Jámbor, Á., Kovács, S., Nagymarosy, A., Szederkény,i T., (2001). Geology of Hungary: Triassic. Budapest: Eötvös University press. 1-317. Jadoul, F., Nicora, A., (1986) Stratigrafia e paleografia ladinico-carnica delle alpi carniche orientali (versante nord della Val Canale, Friuli). Riv. It. Paleont. Strat., 92, 201-238. Karamata, S. (2006). The geological development of the Balkan Peninsula related to the approach, collision and compression of Gondwanan and Eurasian units. in Robertson, A., Mountrakis, D. (eds) Tectonic Development of the Eastern Mediterranean Region. London, Geological Society, Special Publication 260: 155-178.

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Tectonic Control on the Evolution of the Middle Triassic Platforms

373

Kovács S (1982) Problems of the „Pannonian Median Massif” and the distribution of Late Paleozoic-Early Mesozoic isopic zones. Geol. Rubdschau: 71/2: 617-648 Kovács, S. (1984) North Hungarian Triassic facies types. Acta Geol. Hungarica, 2, 251-264. Kovács, S. (1989) Geology of North Hungary. Paleozoic and Mesozoic terraines. In: Kecskeméti, T. XXI st European Micropalaeontological Colloquium. Guidebook. Budapest: Hungarian GeologicalSociety. 15-37. Kovács, S. (1992) Tethys "western ends" during the Late Paleozoic and Triassic and their possible genetic relationships. Acta Geol. Hung 35/ 4, 329-369. Kovács, S. (1997) Middle Triassic rifting and facies differentiation in Northeast Hungary. in Sinha, A.K., Sassi, F.P., Papanicolau D. (eds) Geodynamic Domains in AlpineHimalayan Tethys. New Delhi-Calcutta: Oxford & IBH Publishing Co. Pvt.Ltd. 375-397. Kovács, S., Szederkényi, T., Haas, J., Buda, Gy., Császár, G., Nagymarosy, A., (2000) Tectonostratigraphic terranes in the pre-Neogene basement of the Hungarian part of the Pannonian area. Acta Geol Hung 43, 225-328. Krainer, K., Lutz, D. (1995) Middle Triassic Basin Evolution and Stratigraphy in the Carnic Alps (Austria). Facies, 33, 167-184. Lein R. (1987) Evolution of the Northern Calcareous Alps during Triassic times. In: Flügel H.W. & Faupl P. (ed) Geodynamics of the Eastern Alps: 85-102, Wien, Franz Deuticke. Less. Gy., Mello, J., (ed) Elecko, M., Kovács, S., Pelikán, P., Pentelényi, L., Peregi, Zs., Pristas, J., Radócz, Gy., Szentpéteri, I., Vass, D., Vozár, J., Vozárová, A. (2004) Geological map of the Gemer-Bükk area. 1: 100 000. Mandl, G.W, (2000) The Alpine sector of the Tethyan shelf- examples of Triassic to Jurassic sedimentation and deformation from the Northern Calcareous Alps. Mitt. Österr. Geol. Ges. 92,61-77. Maurer, F. (2000) Growth mode of Middle Triassic carbonate platforms in the Western Dolomites (Southern Alps, Italy). Sedimentary Geology, 134, 275-286. Mello, J., Elečko, M., Pristaš, J., Reichwalder, P., Snopko, L., Vass, D., Vozárová, A., Gaál, L., Hanzel, V., Hók, J., Kováč, P., Slavkay, M., Steiner, A. (1997) Vysvetlivky ku geologickej mape Slovenského Krasu 1:50 000. (Explanatory notes: Slovak Karst) V. of 255. Bratislava: Vydavatel’stvo Dionýza Štúra. McKenzie, D.P. (1978) Some remarks on the development of sedimentary basins. Earth planet. Sci. Letter 40, 25-32. Mostler, H., Krainer, K. (1994) Saturnalide Radiolarien aus dem Langobard der Südalpinen Karawanken (Kärnten, Österreich). Geol. Paläont., Mitt. Innsbruck. 19, 93-131. Pamić, J., Balen D. (2005) Interaction between Permo-Triassic rifting, magmatism and initiation of the Adriatic-Dinaric carbonate platform (ADCP). Acta Geologica Hungarica 48/2, 181-204. Piller, W.E., Egger, H., Erhart, C.W., Harzhauser, M., Hubmann, B., van Husen, D., Krenmair, H. G., Krystyn, L., Lein, R., Lukeneder, A., Mandl, G.W., Rögl, F., Roetzel, R., Rupp, C., Schnabel, W., Schönlaub, H.P., Summesberger, H., Wagreich, M., Wessely, G. (2004) Die stratigraphische Tabelle von Österreich 2004 (sedimentäre Schichtfolgen). Komm paläont strat Erforsch Öster der Öster Akad der Wiss und Öster Strat Kom Wien. Wolkersdorf: Gerin. Placer, L., & Čar, J. (1977) Srednjetriadna zgradba idrijskega ozemlja. (The Middle Triassic Structure of the Idrija Region.) Geologija, 20,141-165.

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374

Felicitász Velledits

Protić, L., Filipović, I., Pelikán, P., Jovanović, D., Kovács, S., Sudar, M., Hips, K., Less, Gy., Cvijić, R. (2000) Correlation of the Carboniferous, Permian and Triassic sequences of the Jadar block, Sana-una and „Bükkium” terranes. In: Karamata S. & Jankovič S. (Eds.) Proc. of the international symposium: Geology and metallogeny of the Dinarides and the Vardar zone. Acad. Sci. Arts Repub. Srpska, Collect. Monogr., Dept. Nat. Math. Tech. Sci. I: 61-69, Sarajevo. Rüffer, T., Zühlke, R. (1995) Sequence Stratigraphy and Sea-Level changes in the Early to Middle Triassic of the Alps: A Global Comparison. In Hag B.U. (ed) Sequence Stratigraphy and Depositional Response to Eustatic, Tectonic and Climatic Forcing. Dordrecht, Kluwer: Academic Pulishers. 161-207. Schafhauser, M. (1997) Stratigraphy und Fazies in der Mitteltrias der Südkarawanken (Kärnten/Österreich). Final Thesis. Univ: Berlin. 1-161. Unpublished. Schlager, W., Schnöllnberger, W. (1975) Das Prinzip der stratigraphischen Wenden in der Schichtfolge der Nördlichen Kalkalpen. Mitt. Geol. Ges. Wien. 66-67, 165-193. Senowbari-Daryan, B., Zühlke, R., Bechstädt, T., Flügel, E. (1993) Anisian (Middle Triassic) Buildups of the Northern Dolomites (Italy): The Recovery of Reef Communities after the Permian/Triassic Crisis. Facies, 28, 181-25. Sudar, M., Kovács, S., Karamata, S., Haas, J., Gawlick, H.J., Péró, Cs., Gaetani, M., Gradinaru, E., Mello, J., Polák, M., Aljnović D., Ogorelec, B., Kolar-Jurkovšek, T., Jurkovšek, B., Buser, S. (in press). Triassic environments in the Circum-Pannonian region related to the initial Neotethyan rifting stage. Geologica Carpathica Sudar, M.N., Budurov K.J. (1983) Conodont succession in the Illyrian of Pridvorica near Sarajevo (Inner Dinarides, Yugoslavia). Radovi Geoinstituta 16,180-182. Tatzreiter, F. (2001) Noetlingites strombecki (Griepenkerl 1860) und die stratigraphischen Stellung der Grossreifling Ammonitenfaunen (Anis, Steiermark/Östzerreich). ) Noetlingites strombecki (Griepenkerl 1860) and the stratigraphical position of the ammonite-faunas of Grossreifling (Anisian, Styria/Austria). Mitt.Ges.Geol.Bergbaustud.Österr. 45, 143-162. Tollmann, A. (1987) New directions on the Geology of the Eastern Alps and their connection to the Eastern Mediterranean. Mitt der Österr Geol Ges 80,47-113. Trubelja, F. (2003) Two genetic rare bauxite deposits in the karst of the Dinarides (Bosnia and Herzegovina) – 22nd IAS Meeting of Sedimentology – Opatija 2003, Abstracts Book. Zagreb: 210. Velledits, F. (2004) Anisian terrestrial sediments in the Bükk Mountains (NE Hungary) and their role in the Triassic rifting of the Vardar-Meliata branch of the Neo-Tethys ocean. Rivista Italiana di Paleontologia e Stratigrafia. 110, 659-679. Velledits, F. (2006) Evolution of the Bükk Mts. (NE Hungary) during the Middle–Late Triassic asymmetric rifting of the Vardar-Meliata branch of the Neotethys ocean. International Journal of Earth Sciences (Geol. Rundsch) 95, 395-412. Velledits, F., Péró, Cs., Blau, J., Senowbari-Daryan, B., Kovács, S., Piros, O., Pocsai, T., Simon, H., Dumitrică, P., Pálfy, J. (in prep): The oldest Triassic platform margin reef from the Alpine–Carpathian Triassic, Aggtelek, NE Hungary. Facies Vörös, A. (ed), Budai T, Lelkes Gy, Kovács S, Pálfy J, Piros O, Szabó I, Szente I, Vörös A (2003b) The Pelsonian Substage on the Balaton Highland (Middle Triassic, Hungary). Geol Hung, ser Paleont, 55, 1-195. Budapest: Hungarian Geol. Inst.

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Wernicke B (1981) Low-angle normal faults in the Basin and Range Province: nappe tectonics in an extending orogen. Nature 291: 645-648 Wernicke, B. (1985) Uniform-sense normal simple shear of the continental lithosphere. Can J Earth Sci 22, 108-125. White, N., Lovel, B. (1997) Measuring the pulse of a plume with the sedimentary record. Nature 387: 888-891. Ziegler, A.P., Stampfli, M. (2001) Late Palaeozoic-EarlyMesozoic plate boundary reorganization: collapse of the Variscan orogen and opening of Neotethys. Brescia: “NATURA BRESCIANA” Ann. Mus. Civ. Sc. Nat.. Monografia N. 25:17-34. Zühlke, R. (2000) Fazies, hochauflösende Sequenzstratigraphie und Beckenentwicklung im Anis (mittlere Trias) der Dolomiten (Südalpin, N-Italien). Gaea Heidelbergensis 6, 368.

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In: Geomorphology and Plate Tectonics Editors: D. M. Ferrari, A. R. Guiseppi

ISBN: 978-1-60741-003-4 © 2009 Nova Science Publishers, Inc.

Short Communication C

MORPHOSTRUCTURE PECULIARITIES OF PAY ZONES AT THE CONTINENTAL MARGINS OF THE NORTH-WEST AUSTRALIA A. Zabanbark* P.P. Shirshov Institute of oceanology of RAS, Moscow, Russian Federation

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ABSTRACT The problem is the definition of morphostructure diagnostic signs of the pay zones from the all territory of the sedimentary basin, for it study by precise and reliable methods so far as the search and the prospecting of the hydrocarbons in the deepwater regions at present technically are limited and economically no profitable. For solving this problem is using the bathymetric map of the continental margin of North-West Australia ( Carnarvon basin as a model ). For revealing of geomorphologic particularities of the pay zones in the considering basin with help of specialized GIS technology were processing digital maps (figure maps) of the bottom relief. Is determined that fields are situated in the narrow zone with frequent and disorderly changing of azimuth dip of the bottom surface of the continental margin, that is characteristic signs of the pay zone. Analogous trends are mapping in the more deepwater regions of the continental slope, so it may consider as prospective for hydrocarbons search.

MORPHOSTRUCTURE PECULIARITIES OF PAY ZONES OF CONTINENTAL MARGINS AT THE NORTH-WEST AUSTRALIA Recent continental margins and in large sense the passage zones from continent to ocean become not only important regions of intense exploration of liquid and gaseous hydrocarbons, but its production. At present the platforms of drilling are visible not only at the shelf, but also at the continental slope. At future the objects of the interest of the oilmen will become *

Correspondence to: [email protected]

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A. Zabanbark

the depth over 2000-3500 m, that is lower part of the slope and the rise. The attraction to this part of ocean is related not purely in scientific plan, but also because in the entrails of the shelves and continental slopes prospectors are waiting one of the very important vital natural gift – oil and gas, reserves of which are capable to provide the consumption of humanity for more decades. The principal problem of the work is to distinguish from all the territory of the oil and gas bearing basin the zones , which are already really, by force of technical and economical limitations, would been possible to study by precise and reliable methods. As rule in these cases used the results of drilling, seismic prospecting, gravimetric and magnetometry studding. The bathymetric data, most widespread and sufficient accessible, usually didn’t employ during the oil and gas bearing prognostic of continental margins. Below, it is describing about the results of morphostructure peculiarity studies of the North-West Australian continental margin on the base of the bathymetric maps analysis by specialized geographical information system (GIS technology). After studies of the tectonic of oil and gas bearing regions of West Siberia and Siberian platform it is determined the timing of hydrocarbon fields to the structures, formed in conditions of horizontal tensions arising in result of different amplitude of the adjacent elevation of tectonic blocks [6]. This process is calling by the geologists as gravitational tectogenesis. Belaousov V.V. [1] shown, that the formation of folds in these conditions is accompanied by arising of conjugate zones of local geodynamic distension – them correspond local zone of geodynamic compression with more steep and asymmetric folds. Most of known fields are disposing under local geodynamic zones of distention, in the region where the brachy-form folds is developing gently. The importance of the discovery phenomenon conclude that the productive local geodynamic zones are a particular morphostructure form. By analogy with productive zones of onshore may expect, that in the ocean, in geodynamic local zone of compressions the structure of bottom relief would be more steep, with more clear manifested stretch of the bottom morphostructure, than the local geodynamic zones of distensions. As a model for realization the method about morphostructure analysis of sedimentary basin on the continental margin is choosing the well studied oil and gas bearing Carnarvon basin [3,4], situated on the North-West of Australian continental margin. The mentioned basin is extend about 1000 km along the North-West sea coast of Australia and 300 km wide. One part of the basin is on onshore and the other part is covered by the water of the Indian ocean. In the North part of the basin distinguished three depressions: Dampier, Barrow and Exmouth [2,5,]. Total thick of the sediments in the basin attains 15 km. After the first discovery of the oil field – Raf-Range in 1953 till to day numbered more 80 fields of oil, gas and condensate [7]. Pay layers are Lower Cretaceous, Upper, Middle and Lower Jurassic and Triassic (tab.). At the same time, can say the basin requires some further studies. For geomorphologic particularities revelation of the pay zones, analogous to the determined in Siberia, in considering basin were choosing digital maps of the bottom relief by helps of specialized GIS technology. As analogy to the analysis of the geophysical areas, the area of the bottom relief have been divided by sliding window for regional and local composing ( analysed the results of the smooth in different windows and choosing the optimum) calculated a series of derivative signs: mainly linear stretch of the relief elements, vertical and horizontal gradients of the bottom surface and others, the whole are 12 signs

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(maps). For every sign have been constructed digital maps. In this article considering the analysis results of 3 maps – regional bottom relief of the basin (fig1), local relief and the map of mainly stretch of azimuth dip of the bottom surface(fig.2) and the profile across the hydrocarbon fields, shown the change of the studied morphostrucrure signs (fig.3). According to the adoption geodynamic model, that pay zones must differ by steep changeability of mainly stretch linear relief elements and timed to the peripheral zone of local structures of the bottom relief ( local relief is a sign, formed by subtraction of regional relief from real bottom relief). The profile across a group fields Goodwin – Egret – North-Rankin – Angel shows, that all the fields are situated on the slope of the local relief elevation (fig.3). This zone of bottom is characterized by steep and most local changes mainly linear stretch of relief elements, that contrasted to the quiet, stable direction on the bottom slopes in neighbours non – pay zones. Table 1. Some oil and gas fields on the continental margin of the North-West of Australia Fields

Pasco Legendre North-Rankin

Depth of pay laying horizon , м. 667-784 1665-1667 1854-2234 1530-1840 3067-3400 2650-3350

К1 К1-J3 J Mz, K J2 T3-Т2

Rankin

2605-2655

Mz

Angel

2635-2690

J1

Goodwin

2455-2860

T3,T2

Egret West-Trial East-Mermed South-Pepper Iglhoouk

1213-1218 2180-2182 2750-2788

Mz K1-J3 J2-J1 T3

Talisman Gorgon Saladin Lambert Chervil Harriet

2925 2282 -

J2 K1- J3 -

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Barrow

Age of horizon

pay

Reserves of oil, million t, gas, billion м3 37 20 396

Depth of sea, м.

-

92

-

92

147

133

-

18200 425 18

oil

-

oil gas oil oil oil oil

-

1 21 180 200 22 402 125 121

Nature of fluid

oil oil oil gas, oil Oil gas, condensate gas, condensate, oil gas, condensate gas, condensate oil gas gas gas

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128

102 52 200

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A. Zabanbark

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Figure 1. Survey map of the study region. Conventional signs: 1- fields: 1-Saladin; 2-Chervil; 3-South Pepper; 4- Harriet; 5-Barrow; 6-Pasco; 7-West-Trial; 8-Rankin; 9-North-Rankin; 10-Goodwin; 11Angel; 12-Legendre; 13-Egret; 14 –Gorgon; 15-Talisman; 16-Iglhoouk; 17-Lambert; 18-East-Mermed. 2 – coast; 3 – depth of the ocean; 4 – line of profile; 5 – North-West boundary of the Carnarvon sedimentary basin

Figure 2. Map of azimuth dip of the bottom surface of the continental slope of North – West Australia. Conventional signs: 1 – lines of equal significances of azimuth dips of ocean bottom and significances azimuths (figures); 2 – fields: 1-Saladin; 2-Chervil; 3-South-Pepper; 4-Harriet; 5-Barrow; 6-Pasco; 7West-Trial; 8-Rankin; 9-North-Rankin; 10-Goodwin; 11-Angel; 12-Legendre; 13-Egret; 14-Gorgon; 15-Talisman; 16-Iglhoouk; 17-Lambert; 18-East-Mermed; 3 – coast; 4 – line of profile. The fields are situated in the narrow zone with frequent and disorderly changes azimuth dip of the bottom surface of continental slope, that is character signs of the local zones of geodynamic tension.

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381

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The zones with typical combination of favourable signs extending as a trend along the North-West sea coast of Australia (2). 17 from 18 considering fields, are situated in the discovery trend, this permits to count the proposing hypothesis about timed of fields to the geodynamic zones and to the typical area of there morphostructure manifestation is justified. Analogous trend are observing in more deepwater parts of the continental slopes (fig2), these zones may be consider as a potential for hydrocarbons prospecting. The first studded of morphostructure analysis of the oil and gas bearing of Carnarvon basin on the continental slope shown not only the efficiency of the accounted approach, but it permits to project series perspective zones disposing in the trend, situated at the West, North and South of the oil and gas fields already have been revealed. As far as the technique of prospecting and reclamation of oil and gas fields in the deepwater regions is not far yet quiet and is very expansive, than the using of the proposed method, which have been yet proved on the onshore, would increased the profitable of exploration, prospecting and exploitation of oil and gas fields on the continental slopes and rises of the World ocean.

Figure 3. Profiles across the fields: Goodwin, Egret, North-Rankin, Legendre (1,2). 1 – Profile 1 show, fields are situated on the slope of local relief. Local relief is obtained by subtraction regional relief from real. 2 – Profile 2 show the position of the fields Goodwin – Legendre in real relief on the continental shelf of the North-West Australia. Pay zones are arranged on the bottom areas nothing noteless.

REFERENCES [1] [2] [3] [4] [5]

Belousov V.V. Types and origin of folding.//Soviet Geology. 1958. P.40-64. BHP Billiton LTD…oil and gas discovery in the Exmouth subbasin of the Carnarvon basin// Oil and Gas J.2003.V.101.№ 30. P.8. Geodekyan A.A., Zabanbark A. Geology and habitat of oil and gas resources in World ocean. M. : Naouka. 1985. 191p. Geodekyan A.A., Zabanbark A., Konyoukhov A.I. Tectonic and lithology problems of oil and gas bearing in continental margins. M. : Naouka. 1988. 176 p. Meredith Chris. WALNG project’s fortunes reflected in Greater Gorgon.//Oil and Gas J.2006. V. 104. № 42. P.52-54.

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

382 [6]

Ulmasvay F.S. Geodynamic position of oil and gas fields at the ancient platform// Abstract XIV Gubkin reading.M. 1996. P. 49. Williamson P.E., Poidevin S. Discoveries, pending developments belie 2004 slide in Australia oil, gas reserves.//Oil and Gas J. 2005. V. 103. № 39. P. 34-41.

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[7]

A. Zabanbark

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INDEX

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A Abiotic, 139 absorption, 2, 5, 13, 27 absorption coefficient, 2, 5 accidents, 89, 90, 342 accounting, viii, 35, 107 accuracy, 13, 43, 45, 47, 48, 61, 216, 224, 242, 341, 354 acid, 87, 150 activation, 4 acute, 161 Adams, 94, 305 adaptation, 85, 86, 90, 95 adjustment, viii, 16, 97, 98, 100, 107, 108, 109, 114, 123, 125 Afghanistan, 306 Africa, vii, xii, 22, 142, 151, 153, 157, 158, 160, 246, 258, 262, 267, 311, 312, 316, 320, 324, 325, 326, 327, 329, 330, 331, 332, 334, 335, 337, 338, 340, 341, 342, 343 age, ix, xiii, 1, 3, 8, 9, 11, 12, 14, 15, 23, 26, 117, 160, 165, 167, 169, 171, 173, 177, 179, 183, 184, 193, 197, 199, 200, 201, 204, 208, 209, 210, 213, 216, 217, 219, 225, 227, 228, 233, 234, 235, 238, 276, 279, 280, 285, 300, 316, 328, 334, 359, 360, 363, 366, 368, 370, 371 agents, viii, 97, 108, 118 agricultural, 51, 118, 119, 131, 135 agricultural crop, 51 agriculture, 36, 37, 39, 87, 88, 89 air, 16, 57, 86, 245, 246, 350 Alaska, xi, 81, 83, 85, 87, 88, 91, 92, 94, 95, 106, 113, 275, 276, 279, 296, 297, 299, 300, 304, 305, 306, 307, 308, 309 Alberta, 137, 281, 283 algae, 298

Algeria, xii, 311, 312, 315, 327, 328, 329, 331, 338, 339, 340, 341, 342, 343 algorithm, 211 alienation, 88 alkali, 230 alkaline, 172, 183, 200, 213, 262 allies, 285, 286 alluvial, viii, 24, 26, 35, 50, 51, 52, 111, 112, 114, 115, 362 Alps, viii, xiii, 55, 56, 57, 58, 61, 80, 81, 82, 359, 360, 362, 363, 366, 370, 371, 372, 373, 374 alternative, 135, 356 alternative energy, 356 ambiguity, 103 amplitude, 19, 42, 53, 62, 79, 250, 253, 254, 256, 261, 269, 326, 327, 346, 378 AMS, 2, 3, 4, 7, 8, 20, 27 Amsterdam, 271, 338 analytical techniques, 3 Andes, 81 Angiosperms, 87 animals, 106, 291 anisotropy, 165, 228 Antarctic, 87, 115 anthropology, 88 anxiety, 91 application, xiii, 2, 17, 28, 42, 53, 108, 109, 119, 135, 208, 262, 341, 345, 355, 356 aquifers, 142 Arabia, 326, 334, 340 Arctic, v, viii, 22, 23, 82, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 113, 162, 189, 228, 231, 233, 235, 277, 278, 280, 281, 282, 283, 286, 287, 288, 289, 290, 291, 292, 293, 294, 295, 297, 298, 300, 303, 306, 308, 363 Arctic Ocean, 86, 87, 90, 91, 92, 93, 190 argument, 91, 101, 231 arid, 25, 100, 120

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Index

384

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Arizona, 25, 26, 27, 111, 112, 116, 137, 138, 139, 277, 280, 281, 282, 285, 286, 287, 289, 293, 298, 299, 308 ARS, 137, 138 ash, 106 Asia, x, 53, 54, 160, 161, 162, 165, 180, 187, 198, 199, 209, 211, 216, 221, 223, 225, 226, 227, 231, 233, 235, 236, 270, 272, 276 Asian, 54, 160, 162, 198, 213, 222, 225, 226, 228, 231, 233, 265 assessment, 19, 43, 47, 48, 49, 65, 82, 101, 107, 109, 136, 143 assumptions, 8, 9, 19, 22, 25, 151 asymmetry, 88, 372 Atlantic, xii, 57, 91, 311, 315, 316, 320, 322, 326, 327, 329, 330, 331, 336, 339 Atlantic Ocean, xii, 57, 311, 315, 316, 329, 330, 331, 336 Atlas, xii, 83, 270, 311, 312, 313, 315, 316, 317, 318, 319, 321, 322, 324, 326, 327, 328, 329, 330, 331, 337, 338, 339, 340, 341, 342, 343, 357, 372 atmosphere, 4, 6 atoms, 2, 4 attitudes, 208, 216 Australia, vi, vii, xiv, 22, 111, 112, 120, 160, 165, 177, 178, 187, 226, 230, 235, 236, 377, 378, 379, 380, 381, 382 Austria, 372, 373, 374 availability, 89 averaging, 208, 220 aviation, 355

B Baikal, 179, 181, 184, 200, 227, 236 baking, 165 Bangladesh, 36, 53 banks, 106, 135, 146 barriers, 107 basic research, 224 bathymetric, xiv, 377, 378 batteries, 356 bauxite, 374 Bayesian, 139 beaches, 113 behavior, 12, 115, 166, 269 Belgium, 138 bending, 88, 273 benefits, 92 bias, 26, 254 bifurcation, 120 biogeography, 233, 305 biota, 94, 165

biotic, 103 blocks, xi, xii, 106, 160, 163, 165, 171, 177, 178, 182, 185, 195, 201, 210, 222, 229, 263, 266, 271, 275, 276, 301, 303, 304, 305, 311, 318, 319, 322, 326, 327, 334, 335, 378 blood, xiii, 345, 346, 349, 350, 351, 352, 353, 354, 357 blood smear, 350, 351, 353, 354 bogs, 90 boreal forest, 86, 106 boreholes, 153 Bosnia, 374 Boston, 339 boundary conditions, 23, 100, 107 bounds, 108 branching, 51 Brazilian, 25 Britain, 136 British Columbia, 297, 299, 300, 301, 303, 304, 305, 306, 307, 308 buffer, 51, 52 buildings, 88, 91, 198 burn, 106

C caldera, 106, 114 calibration, 16, 22, 42, 119, 232 Cambodia, 36, 37, 39, 49, 50, 53 Cambodian, v, viii, 35, 36, 37, 38, 39, 41, 42, 49, 50, 51, 52, 53 Cambrian, 169, 180, 181, 182, 183, 184, 185, 186, 187, 190, 191, 193, 218, 222, 225, 228, 229, 230, 231, 233, 234, 252 campaigns, 126 Canada, viii, 23, 85, 86, 87, 89, 91, 93, 227, 229, 231, 232, 276, 277, 281, 282, 283, 285, 286, 287, 288, 289, 292, 293, 294, 295, 305, 306, 307, 308 candidates, 15 capitalist, 88 carbon, 94, 349 carbon dioxide, 349 carbonates, 298, 305, 332, 341, 363, 366, 367 Carpathian, vi, xiii, 359, 361, 362, 367, 369, 370, 374 catastrophes, 113 catchments, ix, 26, 115, 117, 118, 120, 121, 122, 123, 125, 126, 127, 132, 134, 136, 142, 158 cattle, 89, 145, 146, 156 causality, 113, 115 cave, 15, 27 cavities, 148, 150 cell, 152, 349

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Index Central Asia, x, 160, 161, 162, 165, 187, 197, 198, 199, 211, 213, 216, 221, 222, 225, 226, 231, 236 channels, ix, 50, 88, 105, 111, 114, 115, 117, 119, 120, 122, 125, 135 Chile, 273 China, x, 160, 178, 199, 209, 210, 212, 222, 226, 230, 236, 363 circulation, 86, 93, 122 CIS, 241, 247, 248, 265 classes, 62, 67 classical, 346, 371 classification, viii, 35, 37, 39, 42, 43, 50, 51, 52, 53, 113, 167, 169, 176, 200, 204, 208, 216, 219 clay, 50, 125, 150, 153 climate change, viii, 26, 85, 86, 88, 89, 90, 91, 92, 93, 94, 95, 110 climate warming, 56, 91 closure, x, 160, 162, 180, 187, 195, 199, 200, 210, 212, 213, 222, 223, 231, 232 clustering, 99, 107 Co, 41, 113, 115, 120, 270, 288, 289, 290, 291, 292, 294, 367, 372, 373 CO2, 93 coal, 205 coastal communities, 91 coatings, 354, 355, 356 Cochrane, 122, 136, 137 coding, 65 coherence, 53 cold war, 95 Cold War, 91, 92 collisions, 271 Colorado, 26, 83, 105, 110, 111, 114, 115, 137 colors, 149 Columbia, 109 Columbia River, 109 communities, viii, 85, 86, 88, 89, 91, 372 community, 101, 161 compaction, 142, 146 compensation, 242, 245, 246, 254, 267 competition, 87 compilation, 176 complexity, 62 complications, 90 components, 5, 102, 104, 105, 107, 120, 123, 128, 165, 166, 169, 199, 200, 240 composition, 39, 169, 183, 200, 213, 222, 227, 235, 280, 282, 294, 318 computing, 118 concentration, 2, 6, 9, 10, 11, 12, 14, 18, 20, 24, 25, 118, 142, 167, 169, 171 conception, 199 conceptual model, 109

385

conceptualization, ix, 97, 102 concrete, 132 conductive, 247 conductivity, 119, 125, 151, 153, 154, 238, 247 confidence, 120, 165, 167, 168, 169, 171, 177, 181, 186, 200, 201, 203, 204, 206, 208, 211, 213, 215, 216, 217, 220, 224 configuration, 151, 173, 183, 209, 230, 268 conformity, xi, 237 confusion, 57 Congress, iv, 139, 234 consensus, 88 conservation, 118, 122, 139, 151 consolidation, 119, 135 constant rate, 11 Constitution, 65 constraints, 23, 94, 100, 108, 148, 229, 231, 233, 253, 291, 293, 305, 372 construction, 132, 190, 219 consumption, 378 contamination, 20, 88 contextualization, 102 continental shelf, 193, 262, 381 continuity, viii, 87, 97, 123 control, viii, 22, 35, 41, 45, 47, 118, 122, 138, 142, 351, 363, 370 convection, 266 convergence, xi, 79, 172, 193, 210, 237, 238, 239, 245, 246, 247, 249, 251, 265, 266, 269, 316, 343 convex, 145, 146, 157 cooling, 213, 298, 303 coral, xi, xii, 115, 275, 279, 280, 289, 291, 292, 294, 295, 297, 298, 300, 301, 303, 305, 309 coral reefs, 115 correlation, 39, 66, 69, 79, 165, 177, 189, 193, 195, 196, 197, 215, 228, 233, 270 correlations, 119, 222 cosmic ray flux, 16, 18 cosmic rays, vii, 1, 3, 4, 6, 15 costs, 92 coupling, 80 covering, 163, 195 crack, 356 cracking, 153 creep, 20, 55, 82 critical value, 167, 169, 171, 200, 204, 208, 215, 216 Croatia, 371 crops, 89 crust, x, 160, 162, 179, 181, 186, 191, 195, 209, 222, 238, 242, 246, 247, 249, 251, 253, 255, 256, 262, 265, 266, 268, 269, 270, 271, 327, 334, 363, 367, 370, 371 crystalline, 60, 74, 78, 83, 171, 242

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Index

386 crystallization, 226, 230, 368 CSS, 70 cultivation, 39 culture, 88, 89 cycles, 23, 27, 101

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D Darcy’s law, 151 data analysis, 41 data collection, 157 data generation, 123 data processing, 346 data set, x, 40, 41, 159, 161, 162, 176, 182, 198, 199, 246, 256, 263, 265 database, 61, 62, 65, 66, 196, 198 dating, vii, 1, 3, 10, 12, 15, 22, 23, 24, 26, 166, 172, 204, 213, 224, 328, 334 deaths, 89 decay, 2, 6, 10, 15, 25, 27, 202, 204, 205, 207, 262 deciduous, 89 deep-sea, 317, 318, 319, 336 defects, 357 deficiency, 101, 353, 354 definition, xiii, 103, 276, 372, 377 deformation, x, 55, 160, 185, 189, 195, 198, 199, 201, 209, 216, 219, 222, 316, 328, 338, 373 degradation, 56 degrees of freedom, 68 delivery, 111 demagnetization, 166, 170, 172, 199, 202, 204, 205, 207, 209, 214, 216, 218 Denmark, 86, 91 density, x, xi, 2, 5, 20, 69, 73, 74, 127, 144, 237, 238, 240, 242, 245, 246, 247, 248, 249, 251, 252, 253, 254, 256, 258, 260, 265, 267 Department of Agriculture, 137 deposition, 2, 9, 11, 17, 18, 26, 79, 105, 119, 124, 129, 171, 194, 197, 354, 356, 368 deposition rate, 2, 9 deposits, xii, 23, 57, 61, 101, 115, 164, 165, 166, 172, 180, 183, 184, 186, 189, 190, 191, 195, 197, 205, 207, 209, 214, 217, 230, 282, 311, 315, 316, 322, 324, 328, 374 depressed, 56 depression, 120, 190, 200, 201, 203, 205, 206, 207, 209, 213, 225, 226 desiccation, 146 destruction, 51, 53, 142, 221 detachment, 119, 123, 130, 316, 335 detection, 53, 346 detritus, 135 deviation, 165, 215, 218, 348

diagenesis, 230 differentiation, 80, 278, 367, 373 diffusion, 17 diffusion rates, 17 dimensionality, 98, 99 dipole, 16 direct measure, 26, 131 direct observation, 230, 346 disaster, vii, 35, 53 discontinuity, xi, 146, 238 discordance, 362 discounts, 21 discourse, 90 diseases, xiii, 89, 345, 349, 357 disequilibrium, 114 dislocation, 340 displacement, 86, 88, 106, 180, 210, 211, 221, 301, 360 disputes, 91 distribution, viii, 10, 23, 25, 35, 42, 50, 55, 57, 63, 64, 65, 66, 67, 68, 69, 72, 74, 75, 76, 77, 78, 79, 80, 81, 82, 86, 87, 89, 94, 106, 125, 126, 130, 154, 167, 170, 173, 179, 195, 196, 197, 210, 217, 220, 242, 280, 291, 294, 297, 304, 305, 306, 348, 349, 373 diversity, 88, 278, 279, 280, 281, 283, 286, 288, 293, 294, 295, 297, 298, 303 dominance, 256 drainage, 25, 88, 89, 106, 112, 113, 114, 120, 122, 123, 124, 125, 126, 127, 129, 130, 131, 132, 133, 134, 135, 137, 142, 153 drowning, xiii, 360, 363, 365, 366, 367, 370, 371 duality, 137 Dupuit, 142, 143, 151, 157 duration, 2, 7, 13, 14, 15, 18, 19, 26, 87, 104, 107, 154, 197, 198, 222, 230 dust, 20 dykes, 142, 146, 156, 175, 176, 227, 231, 248, 250, 261, 272, 326, 366

E earth, vii, viii, 42, 97, 98, 102 Earth Science, 3, 21, 54, 110, 269, 338, 341, 343, 374 earthquake, 114, 270 echinoderms, 298 ecological, 293 economic development, 89 ecosystem, 86 ecosystems, 88, 89, 138 egg, 86 Egypt, 327, 338, 341, 342

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Index elasticity, 108 electric field, 7 electromagnetic, 40 electron, 346, 349, 354 electron microscopy, 346, 349, 355 e-mail, 159 energy, 4, 85, 88, 90, 91, 107, 115, 356 England, 85 environment, 25, 85, 88, 93, 128, 134, 135, 169, 177, 180, 182, 185, 187, 194, 198, 222, 349, 356 environmental change, 49, 50, 80, 88, 310 environmental characteristics, 134 environmental conditions, ix, 88, 89, 105, 117, 123, 292, 293 environmental contamination, 88 environmental factors, 80, 98, 113, 293, 294 equilibrium, 6, 8, 10, 11, 12, 13, 14, 25, 26, 60, 81, 103, 113, 114, 146 equilibrium state, 113, 114 erosion, vii, ix, xi, 1, 2, 3, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 18, 20, 21, 22, 23, 24, 25, 26, 28, 79, 80, 81, 87, 91, 93, 105, 115, 117, 118, 119, 121, 122, 123, 124, 126, 128, 130, 131, 135, 136, 138, 139, 141, 142, 146, 149, 156, 158, 237, 245, 266, 322, 362 erythrocyte, xiii, 345, 349, 350, 351, 352, 353, 354, 357 erythrocytes, xiii, 345, 346, 349, 350, 351, 352, 353, 354, 357 Eurasia, v, ix, x, 91, 93, 159, 160, 187, 189, 190, 198, 199, 210, 211, 218, 223, 226, 233, 330, 334 Europe, 89, 138, 199, 209, 211, 212, 219, 220, 222, 226, 324, 337, 342, 343 European Union, 157 evacuation, 51 evolution, vii, ix, xii, xiii, 1, 3, 24, 25, 26, 28, 39, 49, 50, 54, 69, 80, 82, 101, 106, 108, 109, 110, 112, 114, 115, 141, 142, 143, 146, 151, 154, 155, 156, 160, 162, 179, 181, 189, 198, 219, 221, 225, 226, 227, 228, 229, 231, 232, 234, 235, 268, 269, 270, 271, 308, 309, 311, 312, 318, 320, 327, 329, 330, 331, 334, 336, 338, 339, 340, 342, 359, 360, 362, 367, 368, 370, 371, 372 exploitation, 381 exposure, vii, 1, 2, 3, 6, 7, 8, 9, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28, 294 extinction, 228, 298, 303, 308 extraction, 21, 91, 122 extrusion, 204, 208, 213, 215, 326, 327, 328

387

F facies, 50, 54, 169, 190, 293, 294, 318, 322, 342, 343, 367, 373 factorial, 63, 69, 70 family, 295 Far East, 199 farm land, 122 farmers, 95 farming, 37, 87 faults, x, xii, 23, 24, 65, 66, 67, 68, 79, 160, 164, 166, 172, 180, 182, 184, 185, 190, 191, 193, 195, 196, 205, 222, 254, 261, 262, 276, 313, 314, 315, 316, 317, 318, 319, 320, 322, 324, 326, 327, 331, 332, 334, 335, 336, 375 fauna, 88, 194, 282, 285, 286, 289, 291, 293, 294, 295, 298, 304 feedback, 87, 89, 103 Fennoscandian, 23 film, 354, 355, 356, 357 films, xiii, 345, 346, 354, 355 filters, 42, 107, 240 fire, 87, 105, 111, 116, 139 fires, 103, 105, 120 fish, 87, 89, 91, 94 fishers, 89 fishing, 89 fitness, 127, 135 fixation, 132 flank, 156 flexibility, 109 flood, viii, 35, 36, 37, 38, 39, 40, 42, 47, 48, 50, 51, 52, 53, 54, 92, 98, 100, 111, 113, 114, 191, 225, 228, 230, 233, 371 flooding, vii, 35, 36, 37, 38, 39, 41, 42, 43, 45, 48, 50, 51, 52, 53, 91, 105, 109, 112, 118, 135, 138 flora, 88 flora and fauna, 88 flow, viii, ix, 21, 35, 36, 37, 40, 51, 53, 55, 61, 110, 111, 118, 119, 120, 122, 123, 124, 131, 132, 137, 141, 142, 145, 146, 151, 152, 153, 155, 156, 322 flow rate, 37 flow value, 119, 131 fluctuations, vii, ix, 83, 104, 141 fluid, 379 fluvial, viii, ix, 20, 21, 26, 35, 38, 39, 42, 110, 111, 114, 115, 128, 135, 141 focusing, 3, 102, 347 folding, xii, 262, 311, 316, 317, 320, 329, 336, 337, 381 forest formations, 119 forest management, 137 Forest Service, 112, 113, 139

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Index

388 forestry, 41, 89, 119, 121, 135 forests, 87, 94, 137, 139 fossil, 269, 371, 372 Fourier, 269, 271 Fox, 139 fractionation, 94 fracture, 106 framing, 229 France, 36, 55, 57, 61, 83, 272, 338, 339, 341, 342, 343, 344 freedom, 65, 67, 68 frequency distribution, 23 frost, 25 FTC, 133 fuel, 89

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G gas, 2, 7, 87, 91, 378, 379, 381, 382 gases, 88 generation, ix, 25, 110, 123, 127, 141, 153, 156 generators, 123 genre, 98 geochemical, 12, 15, 165, 208, 271, 371 geochemistry, 235, 269 geography, 88, 103, 116, 225 geological history, x, 160, 174 geology, 2, 21, 27, 106, 111, 113, 241, 242, 248, 249, 260, 306, 337, 338, 341 geomagnetic field, 16, 201, 225 geometrical parameters, 62, 347 geophysical, 190, 246, 271, 378 Georgia, 97 geothermal, 90, 263 Germany, 27, 341, 363 gift, 378 GIP, 83 GIS, viii, xiv, 40, 41, 53, 54, 55, 57, 62, 63, 69, 80, 122, 123, 136, 137, 377, 378 glaciation, 23, 79, 83 glaciations, 27 glaciers, v, viii, 23, 55, 56, 57, 58, 59, 61, 62, 63, 64, 65, 66, 67, 68, 69, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 87, 89, 90, 94 glass, 350 global warming, 92, 93, 94, 95 globalization, 89, 92 goals, 21 gold, 95 government, 91 GPS, 40, 42, 126, 132, 224, 234 grain, 20 granites, 166, 167

grants, 224 grass, 56, 88, 126 grasses, 126 gravity, viii, x, xi, 97, 106, 108, 190, 237, 238, 240, 241, 242, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256, 258, 262, 267, 268, 270, 271, 272, 273, 319, 341, 342 grazing, 152 greenhouse, 88, 94 greenhouse gas, 88 greenhouse gases, 88 Greenland, 82, 85, 87, 89, 91, 95, 179 grid resolution, 61, 154 groundwater, vii, ix, 141, 142, 143, 145, 146, 148, 151, 153, 154, 155, 156 grouping, 167, 169, 171, 201, 208 groups, 63, 68, 69, 118, 170, 184, 213, 240, 278, 279, 280, 292 growth, ix, 6, 24, 100, 110, 115, 119, 128, 141, 142, 144, 146, 147, 160, 162, 179, 181, 233, 316 growth rate, 100, 144 GSP, 231 Guinea, 320

H H1, 245, 252, 253, 256, 261 H2, 245, 252, 256, 258, 261 habitat, 87, 381 half-life, 6, 9, 10, 12, 14, 15 hanging, 322 hardness, 353, 354, 355 harvest, 88, 95, 136 Hawaii, 114 hazards, 56, 82, 107, 115 health, 89, 353 hearing, 353, 354 heat, 236 heating, 240, 371 height, 133, 134, 250, 263 hematological, xiii, 345, 349, 351, 354, 357 hemisphere, 67, 163, 221, 222, 266, 268 hemoglobin, 349, 353 hemorrhage, 353 heterogeneous, 210 high resolution, 61, 143 hip, 142 holistic, 85, 92 Holland, 93, 95 Holocene, viii, 21, 24, 35, 39, 49, 50, 51, 53, 54, 93, 94, 106, 113, 116 hologram, 347, 348 homeostasis, 349, 353

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Index

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homogeneity, 38, 350 homogenous, 335 horizon, 139, 150, 165, 379 host, 102, 165, 167, 213, 215 House, 99, 112 human, viii, xiii, 10, 26, 35, 50, 85, 87, 88, 90, 92, 101, 103, 107, 111, 112, 345, 346, 354 Human Development Report, 94 human interactions, 92 humanity, 88, 378 humans, 85 humidity, 87, 125 Hungarian, 360, 373, 374 Hungary, 359, 372, 373, 374 hunting, 89 hurricanes, 103, 115 hydrate, 94 hydrates, 87 hydro, xiii, 158, 377, 381 hydrocarbon, 272, 378, 379 hydrocarbons, xiii, 377, 381 hydrologic, ix, 36, 114, 141, 152, 153, 154, 156 hydrological, ix, 87, 94, 120, 121, 127, 134, 136, 141, 152, 153, 154, 156 hydrology, 123, 128, 137, 143, 149, 154 hydrophobic, 355 hydrophobic properties, 355 hypothesis, vii, 1, 3, 25, 62, 65, 67, 68, 69, 148, 232, 278, 381 hypothesis test, 62, 69 hypoxia, xiii, 345, 353, 354, 357

I ICAM, 231 ice, 15, 17, 18, 19, 20, 22, 23, 55, 56, 79, 81, 82, 86, 87, 89, 90, 91, 92, 93, 95, 115 Idaho, 82, 113, 136, 139, 309 identification, 42, 137 identity, 56, 89, 225 IES, 112 Illinois, 110, 139 image analysis, 53 imagery, viii, 35, 36, 39, 40, 42, 53, 61 images, xiii, 36, 38, 39, 42, 45, 47, 51, 53, 126, 127, 256, 345, 346, 347, 350, 351, 353, 354, 357 imaging, xii, 272, 345, 346, 354 impact energy, 123 implementation, 80 in situ, 167, 169, 170, 171, 192, 203, 206 inactive, 55, 335 incidence, 40 increased access, 89

389

independence, 80 India, vii, x, xi, 160, 178, 237, 238, 239, 240, 241, 242, 244, 247, 251, 254, 255, 256, 257, 258, 260, 262, 266, 267, 268, 269, 270, 271, 272, 273 Indian, v, xi, 178, 225, 233, 237, 238, 239, 240, 241, 242, 244, 245, 246, 247, 248, 251, 252, 254, 255, 256, 258, 260, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 378 Indian Ocean, 233, 239 Indiana, 137 indicators, 56, 80, 126, 234 indices, 278, 348 indigenous, 88, 89 indigenous peoples, 89 Indo-Pacific, 279 industrial, 89 industry, 89 inertness, 356 infants, 36 Infiltration, 139, 154 Information System, 122, 123 infrared, 36 infrastructure, 90 inheritance, 7, 15, 17, 19, 20, 23, 26 inherited, x, 10, 23, 26, 80, 160, 318, 319, 320, 329, 331, 336 inhomogeneities, 273 inhomogeneity, 236 initiation, 142, 322, 373 injection, 169, 236, 354 injections, 353 injury, iv Innovation, 138 inorganic, 42 insects, 88, 89 insight, 23, 25, 27 instability, 81, 88 institutions, 90, 92 instruments, 3, 118 integration, 89, 98, 123, 224 interaction, vii, viii, 1, 90, 97, 185, 210, 271, 349, 371 interactions, viii, 4, 27, 92, 97, 115, 371 interdisciplinary, 113, 371 interface, ix, 117, 121, 123, 124, 135, 139 interference, xii, 345, 346, 347, 348, 357 interstitial, 200 interval, 62, 63, 65, 105, 106, 124, 154, 163, 173, 176, 181, 185, 190, 195, 196, 197, 204, 216, 221, 222, 233, 242, 263 interviews, 39 intrinsic, 100, 142

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Index

390

intrusions, xi, 166, 167, 169, 170, 171, 176, 179, 184, 208, 213, 215, 216, 225, 226, 230, 231, 237, 239, 243, 251, 266, 318 inventories, 7 inversion, 270, 272, 319, 336, 340, 343 inversions, 93, 337 invertebrates, 110 Investigations, 268, 271 investment, 90 ionization, 7 ionizing radiation, 4 island, x, 12, 13, 91, 159, 162, 164, 165, 171, 172, 173, 177, 179, 180, 181, 182, 183, 184, 185, 186, 187, 191, 221, 247, 265, 293, 367 isolation, 87, 89, 199 isotope, 8, 94, 166, 172, 195, 197, 269, 306 isotopes, 269, 271 Isotopic, 236 isotopic methods, 23 isotropic, 143, 151 Israel, 27 Italy, 53, 81, 141, 341, 372, 373, 374

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J Japan, 35, 36, 41, 53 Japanese, 53 Jordan, v, 97, 341 judge, viii, 35 Jurassic, xii, 196, 199, 200, 201, 203, 209, 211, 212, 216, 217, 218, 219, 220, 231, 246, 258, 262, 308, 309, 311, 312, 315, 316, 317, 319, 320, 321, 322, 323, 324, 325, 326, 328, 330, 331, 332, 334, 336, 340, 341, 343, 373, 378

K Kazakhstan, x, 160, 162, 187, 199, 212, 234, 236 killing, 106 kinematics, 162, 181, 185, 187, 190, 197, 219, 221, 223, 224 King, 30 Kyrgyzstan, 234

L L1, 242, 245, 252, 253, 256, 261 L2, 245, 252, 256, 261, 268 LAB, 255 labor, 7, 90 Lafayette, 1, 137 lakes, 46, 51, 87, 106

lamina, 123, 128 laminar, 123, 128 land, viii, xi, 35, 37, 39, 42, 50, 51, 52, 53, 86, 89, 92, 98, 112, 118, 120, 126, 128, 131, 132, 142, 151, 152, 238, 252, 269 land use, 112, 118, 120, 126, 128, 131 landscapes, viii, 19, 23, 26, 50, 89, 97, 100, 107, 108, 110 language, 88, 124 large-scale, x, 25, 90, 112, 160, 162, 177, 179, 180, 193, 198, 199, 200, 210, 218, 221, 222, 229, 234, 305 larvae, 278 laser, 346, 347, 349 Last Glacial Maximum, 57, 69, 79 Late Quaternary, 112 law, 5, 111, 185, 269 laws, 69, 100 legislation, 118 lenses, 355, 356 Levant, 335 levees, 50, 51, 52 liberation, ix, 117, 119, 121, 122, 123, 131, 132, 133, 134 Libya, 326, 327, 332, 337, 338, 341 life expectancy, 89 lifespan, ix, 117 lifestyle, 89 lifetime, 144 likelihood, 43, 102 limestones, 57, 65, 70, 298, 363 limitation, 17, 21, 26, 108 limitations, vii, 1, 3, 8, 15, 17, 26, 27, 101, 378 linear, x, 26, 103, 119, 120, 144, 146, 237, 239, 240, 245, 246, 252, 255, 257, 258, 263, 265, 266, 378, 379 linear regression, 119 links, 88, 184, 193 liquid water, 24 lithologic, 120, 143, 146, 148 lithosphere, vii, xi, 103, 235, 237, 238, 239, 240, 255, 256, 258, 265, 266, 267, 271, 273, 371, 375 Lithuania, 138 livestock, 142 location, 6, 17, 62, 64, 65, 79, 88, 90, 98, 99, 106, 107, 121, 174, 192, 214, 232, 277, 296, 301, 305 London, 81, 83, 228, 230, 235, 269, 273, 308, 339, 340, 343, 372 long-distance, 278, 309 Los Angeles, 306, 308, 309 losses, 17, 118, 139, 146 low-density, 253 LTD, 381

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Index lungs, 349 Lyapunov, 230 lying, 91, 105, 107, 131, 163, 242, 315, 328, 334

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M M.O., 228, 230 machinery, 40 Madison, 112 magma, 316, 341, 371 magmatic, 162, 165, 167, 179, 182, 186, 189, 197, 221, 222, 229, 238, 246, 316, 317, 320, 325, 370, 371 magnetic, iv, xi, 7, 17, 165, 167, 169, 196, 197, 204, 215, 226, 238, 239, 250, 253, 260, 261, 262, 265, 267, 269, 270, 271 magnetic field, 7, 17, 226, 262 magnetism, 228, 265 magnetite, 28, 265 magnetization, 165, 199, 200, 201, 232, 250, 265 magnetometry, 378 main line, 104 maintenance, 103 Malta, 341 management, 93, 107, 118, 122, 125, 126, 137, 138 mantle, xi, xiii, 23, 195, 197, 200, 213, 227, 230, 237, 238, 249, 254, 255, 256, 258, 259, 260, 265, 266, 267, 270, 271, 272, 360, 362, 368, 370, 371 mapping, viii, xiv, 35, 36, 39, 47, 53, 63, 65, 106, 377 margin of error, 120, 301 maritime, 57 marsh, 113 marshes, 50 Maryland, 270 mask, 132 mass spectrometry, 2, 7 material porosity, 127 material surface, 355 matrix, 45, 50, 263 maturation, 338 Maya, 175, 177, 232 measurement, vii, xii, 1, 3, 7, 13, 15, 20, 21, 24, 25, 27, 39, 40, 61, 128, 268, 345, 346, 349, 353, 354 measures, 13, 90, 138 median, 42 Mediterranean, ix, xii, 57, 117, 118, 119, 120, 134, 138, 276, 311, 316, 319, 326, 327, 328, 331, 332, 335, 338, 340, 342, 372, 374 melt, 226 melting, 86, 87, 88, 90, 92 membranes, 349 men, 353

391

mental state, 349 mental states, 349 meridian, 198 Mesozoic, x, 57, 159, 160, 161, 162, 180, 185, 189, 191, 197, 198, 199, 200, 201, 207, 209, 210, 211, 212, 213, 216, 217, 218, 219, 220, 222, 223, 224, 225, 226, 228, 229, 230, 231, 235, 236, 242, 246, 306, 308, 309, 312, 317, 320, 321, 324, 325, 329, 330, 334, 337, 338, 339, 340, 342, 343, 372, 373 Metallogeny, 232 Metazoa, 165 methane, 87 Mexico, xi, 138, 275, 277, 280, 281, 282, 285, 286, 287, 289, 293, 298, 299, 304, 309 micrometer, 348 microscope, xii, 345, 346, 347, 348, 356, 357 microscopy, 346, 349, 355 microwave, 36, 42 microwaves, 42 migration, 89, 146, 219, 303, 328 militarization, 92 military, 91, 92 mineralization, 236, 243, 371 mineralized, 246 minerals, vii, 1, 3, 4, 7, 17, 26, 171, 246 mining, 87 minorities, 89 Miocene, 254, 360 mirror, 347 misconceptions, 101 misinterpretation, 46 missions, 61 Mississippi, 112, 118 Mississippi River, 112 mixing, 15, 17, 20 mobility, xi, 135, 275, 335 modeling, 63, 75, 76, 77, 78, 80, 81, 115, 137, 139, 265, 267, 270, 371 models, vii, viii, 1, 3, 8, 9, 11, 16, 18, 22, 23, 28, 86, 90, 93, 97, 98, 99, 100, 101, 102, 105, 108, 109, 111, 112, 114, 118, 119, 123, 124, 135, 136, 142, 157, 158, 160, 161, 163, 181, 217, 268, 273, 324, 343, 371, 372 modernization, 89 modulation, 348 modules, 123 moisture, 87, 93, 151 molasses, 164, 183 mole, 319, 336 mollusks, 88 Mongolia, 187, 199, 209, 212, 227, 229, 236 monotone, viii, 35, 36, 38, 39 monsoon, viii, 35, 36, 39, 50, 51

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Index

392

Montana, 227, 309 Monte Carlo, 139 Moon, 157 Morocco, xii, 311, 312, 315, 318, 319, 321, 322, 327, 329, 338, 339, 343 morphological, xii, 56, 62, 64, 65, 69, 106, 111, 345, 346, 349, 350, 351, 352, 353, 354, 357 morphology, xiii, 55, 100, 103, 106, 113, 142, 143, 148, 345, 349, 352, 353, 354, 355, 356, 357 morphometric, 146 mortality, 113, 126 mosaic, x, 42, 160, 180, 187, 221, 360 Moscow, 139, 225, 226, 228, 231, 232, 357, 377 motion, x, 24, 160, 177, 186, 193, 198, 200, 209, 211, 219, 223, 224, 268, 307, 324, 325, 326, 329, 331, 335, 336, 337, 349 mountain environments, 81 mountains, 55, 67, 115, 245, 319, 360 mouth, ix, 141, 146, 217, 218 movement, ix, xi, 24, 105, 106, 107, 112, 115, 141, 142, 143, 151, 154, 162, 187, 237, 238, 266, 267, 272, 278, 303, 320, 322, 327, 331, 335, 360, 361, 362, 370 multidisciplinary, 371 multiples, 341 multivariate, 63, 278 muon, 4, 5 muons, 4, 5

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N NASA, 94, 270 nation, 83, 90 national interests, 91 national security, 91, 92 NATO, 339 natural, viii, 13, 26, 35, 39, 42, 49, 50, 51, 52, 56, 87, 88, 89, 91, 97, 100, 103, 110, 113, 114, 116, 118, 122, 128, 129, 136, 138, 165, 378 natural environment, 49, 50 natural gas, 87 natural hazards, 56 natural resources, 91, 118, 129 NCA, xiii, 359, 363 Nd, 234, 268, 269 Nebraska, 113 negative relation, 142 neglect, 99, 151 Nepal, viii, 55, 57, 59, 61, 80, 81, 82, 83 Netherlands, 94, 225 network, 57, 120, 127, 128, 142, 146, 318, 341 networking, 272 neutrons, 4

Nevada, 16, 113, 277, 281, 282, 283, 284, 285, 286, 287, 288, 289, 293, 295, 297, 298, 305, 306, 307, 308, 309 New Jersey, 139 New Mexico, 138, 277, 280, 281, 282, 285, 286, 287, 289, 293, 298, 299, 309 New South Wales, 112, 120 New York, iii, iv, 92, 110, 112, 137, 268, 310 New Zealand, 24, 27, 111, 113 Newton, 278, 303, 307 Nigeria, 142 NOAA, 36, 124 Nobel Prize, 346 noise, 41, 42 nonequilibrium, 114 normal, 63, 163, 167, 168, 170, 171, 196, 197, 203, 208, 215, 249, 256, 267, 316, 317, 322, 331, 335, 336, 349, 352, 375 normal distribution, 63 normalization, 353, 354 North Africa, vi, vii, xii, 311, 312, 320, 327, 330, 334, 339, 340, 342, 343 North America, vi, vii, xi, xii, 22, 91, 106, 212, 227, 230, 233, 234, 275, 276, 277, 278, 279, 280, 281, 282, 283, 285, 286, 287, 289, 291, 292, 293, 294, 295, 296, 297, 298, 299, 300, 301, 302, 303, 304, 305, 306, 308, 309 Northeast, 91, 111, 316, 332, 336, 338, 373 Northern China, 209 Northern Hemisphere, 86, 93 Norway, 86, 87, 91, 92 NRC, 306 NRM, 165, 202, 204, 218 nuclear, 4, 27, 92 nuclei, 4 nucleons, 4 nucleus, 349 nuclides, vii, 1, 3, 4, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27 null hypothesis, 67, 68 nutrient, 293

O observations, 17, 45, 62, 65, 69, 83, 86, 90, 91, 92, 101, 113, 142, 153, 240, 289 obstruction, 18 oceans, xii, 162, 187, 195, 222, 226, 238, 263, 303, 311 offshore, xii, 89, 246, 258, 275, 279, 293, 303, 321 oil, 90, 91, 119, 378, 379, 381, 382 Oklahoma, 137, 306 old age, 23

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Index online, 337, 341 optical, 54, 346, 347, 349, 354, 355, 356 optical density, 349 optical properties, 356 Ordovician, 183, 184, 185, 187, 188, 190, 193, 195, 222, 226, 228 Oregon, 106, 283, 284, 287, 295, 299, 300, 301, 303, 305 organ, 124 organic, 22, 86, 88, 89, 94 organic matter, 86, 88, 94 organism, xiii, 345, 346, 349, 353, 354, 357 orientation, 163, 185, 198, 211, 253, 319, 330 oscillation, 19 oxidation, 165 oxygen, xiii, 345, 349, 351, 353, 354, 357 ozone, 87, 353

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P Pacific, 91, 190, 226, 279, 306, 307, 308 Pacific Region, 307 Pakistan, 24, 231, 246, 269 paleontology, 305, 307, 309, 371 Pap, 227, 228, 305, 306, 307, 308, 309 parameter, 62, 66, 69, 71, 124, 167, 168, 169, 171, 203, 204, 206, 213, 217, 235 parameter estimation, 235 Paris, 53, 55, 56, 81, 82, 157, 272, 337, 338, 339, 340, 341, 342, 343 particles, 4, 123, 137 Pasco, 379, 380 passive, x, 159, 164, 165, 169, 177, 179, 191, 221, 340 pathogens, 87 pathways, 152 patients, 349, 353 Pb, 171, 232, 233, 234, 235, 371 PCA, 62, 66, 69, 70 peat, 18 perception, 61 perceptions, 90 percolation, 119, 153 periodic, viii, 97, 101 permafrost, viii, 55, 79, 80, 81, 82, 83, 85, 86, 87, 88, 90, 93, 94, 113 permeability, 143, 153, 155 permit, 266, 316 perturbation, 353 pests, 87 Petroleum, 54, 111, 159, 337, 340, 341 Petrology, 229, 235 PFG, 348

393

phase objects, 346 photographs, ix, 61, 62, 141 physical properties, vii, 1 physics, 7, 123, 346 physiological, 87, 353, 354 Pinus halepensis, 121 pipelines, 88 plagioclase, 165 Plagioclase, 4 planar, 17, 18 planetary, 27 planets, 235 planning, vii, 35, 139 plants, 88, 106, 110, 129 plasma, 349 plasma membrane, 349 plastic, 273, 355 plasticity, 355 plate tectonics, vii, 238, 268 platforms, xii, xiii, 91, 232, 235, 311, 319, 339, 359, 360, 361, 362, 363, 366, 367, 370, 373, 377 play, 90, 224 Pleistocene, 27, 49, 50, 54, 94, 329 Pliocene, 21, 329, 336 ploughing, 119 polarity, 163, 167, 168, 169, 170, 171, 196, 197, 203, 208, 215, 229 pollen, 53 pollution, 86, 93 polygons, 61, 62 polymer, 356 pools, 146 poor, 161 population, 90, 142, 204, 208 population density, 142 population growth, 142 porosity, 127, 152, 154 Portugal, 119 positive feedback, 87 post-socialist transition, 89 power, 110, 113, 263, 268, 269 precipitation, 57, 60, 86, 87, 98, 120, 143, 152 prediction, 115, 118, 119, 122, 123, 124, 137, 138 pre-existing, 79 preference, 67, 79, 87 pressure, 16, 89, 142, 316 prevention, vii, 35, 53, 118 PRI, 53 Principal Components Analysis, 62, 69, 71 PRISM, 125 probability, 111, 154 probability distribution, 154 process control, 22

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Index

394

production, 2, 4, 5, 6, 8, 10, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 27, 115, 138, 143, 156, 354, 355, 377 productivity, 87 program, 122, 124, 125, 126, 211 programming, 124 propagation, 24, 51, 122, 325, 327, 331 property, iv, 36, 123 protection, 355 protective coating, 355 protein, 349 protons, 4 proxy, 153, 154, 368 public, viii, 55, 80, 89, 90 pulse, 375 pulses, viii, 97, 102, 108, 368

Q qualitative concept, ix, 97, 101 quartz, 7, 12, 17, 21, 24, 25, 149 quasi-linear, 6, 14 questionnaire, 39

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R radar, 36, 54 radiation, 4, 7, 16, 17, 18, 63, 77, 78, 125, 346, 347, 349, 356 radius, 168, 181, 203, 206, 213, 217, 350, 352 rain, 87, 105, 106, 123, 152 rainfall, ix, 39, 50, 116, 117, 119, 120, 123, 125, 129, 134, 139, 145, 151, 152, 154, 156, 157 random, 65, 66, 67, 68 range, vii, 1, 3, 4, 8, 15, 16, 20, 21, 23, 25, 27, 42, 44, 64, 79, 80, 88, 103, 113, 119, 135, 148, 152, 153, 163, 356, 367 RAS, 228, 230, 234, 377 reaction mechanism, 4 reaction time, 104, 105, 107 reading, 382 real time, ix, 117 reality, 92 reasoning, 334 receptacle, ix, 117, 127, 131, 132, 135 recession, 82 reclamation, 381 recognition, 61 recombination, 183 reconciliation, ix, 97, 98 reconstruction, x, 159, 160, 163, 178, 179, 185, 186, 208, 212, 223, 229, 235, 308, 309, 346, 360

recovery, xii, 99, 100, 103, 104, 105, 106, 111, 114, 311, 372 rectification, 120 recurrence, 105, 106, 110, 111 red mud, 214 redundancy, 66 REE, 169 reef, 372, 374 reefs, 115, 195 refining, 23, 27 reflection, 189, 231, 273 refractive index, 350 refractive indices, 348 regional, vii, ix, x, 23, 24, 27, 35, 56, 57, 91, 98, 106, 118, 141, 165, 190, 198, 204, 210, 237, 238, 245, 246, 249, 252, 253, 267, 334, 371, 378, 379, 381 regolith, 3, 21, 24, 25 regression, 81, 119, 328 regression equation, 119 regular, 37, 39, 40 regulations, 90 rejection, 65, 67, 68 relationship, 18, 26, 27, 28, 53, 85, 100, 102, 119, 122, 142, 143, 154, 155, 232 relationships, viii, 25, 35, 36, 51, 108, 271, 278, 292, 293, 312, 316, 331, 338, 341, 373 relaxation, 111 relaxation time, 111 relevance, 66, 110 reliability, 63, 174, 176, 199, 234, 256, 263, 346 remote sensing, viii, 35, 36, 37, 39, 40, 42, 45, 53, 54, 55, 61, 80 replacement rate, 128 reservation, 108 reserves, 91, 378, 382 reservoir, 94, 120, 148 reservoirs, 105 residential, 51 resilience, 93, 95 resistance, viii, 97, 103, 110, 118 resolution, ix, 12, 13, 41, 42, 61, 125, 126, 141, 143, 154, 346 resources, viii, 27, 85, 88, 89, 91, 118, 129, 381 response time, 104, 107 retardation, 224 retention, 122, 128, 132 Reynolds, 95 rhythm, ix, 117, 132, 133, 134, 135 rice, 39 rifting, xi, xii, 177, 179, 193, 200, 237, 243, 246, 247, 248, 265, 312, 316, 320, 326, 327, 330, 331, 332, 334, 335, 336, 337, 340, 362, 367, 368, 370, 371, 373, 374

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Index risk, vii, 27, 35, 36, 53, 89 risk assessment, 27, 36 risks, 63 river basins, ix, 141 rivers, 51, 108, 111, 112, 113, 142, 200, 203 RM-1, 139 Roads, 51 rocky, 61, 119 Rocky Mountain National Park, 110 rotations, 178, 195, 210, 219, 222, 223, 234 roughness, ix, 117, 357 routing, 112, 113 runoff, ix, 119, 120, 122, 123, 125, 127, 128, 129, 141, 142, 151, 152, 153, 155, 156 rural, vii, 35, 157 rural development, 157 RUS, 157 Russia, 86, 89, 90, 91, 159, 225, 228, 229, 231, 233, 236 Russian, 92, 159, 161, 199, 224, 225, 227, 228, 229, 230, 232, 233, 234, 235, 305, 377 Russian Academy of Sciences, 159, 224

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S safety, 51 salt, 317, 318, 322, 343 salts, 322, 324, 326, 328 sample, 3, 7, 8, 11, 13, 14, 15, 17, 18, 19, 20, 21, 23, 27, 125, 346, 349 sampling, vii, 1, 3, 7, 15, 18, 42, 79, 166, 172, 200, 203, 205, 206, 207, 209, 215, 217, 218, 280 sand, 18, 27, 50, 115, 153, 154, 368 sandstones, 57, 65, 66, 68, 69, 70, 71, 79, 328 SAR, viii, 35, 36, 37, 38, 39, 40, 41, 42, 43, 45, 47, 48, 49, 51, 53, 54, 81 Sarajevo, 374 satellite, viii, xi, 35, 36, 37, 38, 39, 41, 42, 45, 53, 238, 260, 261, 263, 267 satellite imagery, viii, 35, 39, 53 saturation, ix, 141 scalar, 169, 270 scaling, 16, 18, 27 scattering, 36 Schmid, 372 scientific community, 161 scientific knowledge, 90 scores, 174 sea floor, 238 sea ice, 86, 87, 90, 91, 95 sea level, 6, 16, 39, 49, 51, 87, 90, 94, 106, 363, 370 sea-level rise, 87, 90 seals, 88

395

search, viii, xiii, 85, 377 secular, 14, 201, 208 security, 90, 91, 92, 95 sediment, ix, 3, 7, 10, 11, 15, 17, 18, 20, 21, 24, 25, 26, 28, 39, 40, 50, 53, 54, 87, 93, 105, 106, 111, 112, 116, 117, 118, 119, 120, 121, 122, 123, 124, 127, 128, 129, 130, 131, 132, 133, 134, 135, 138, 142, 250, 262, 269, 363 sedimentation, ix, xii, 50, 105, 114, 117, 122, 123, 132, 133, 136, 158, 177, 226, 311, 312, 316, 341, 367, 370, 371, 373 sediments, vii, xii, xiii, 1, 3, 4, 15, 17, 20, 21, 24, 27, 49, 87, 93, 113, 130, 165, 183, 190, 191, 195, 208, 219, 222, 229, 232, 234, 241, 242, 243, 245, 247, 248, 266, 311, 321, 359, 360, 362, 363, 366, 367, 368, 370, 374, 378 segmentation, 137 seismic, xi, 79, 238, 246, 247, 251, 252, 253, 256, 258, 265, 267, 269, 270, 271, 272, 322, 326, 335, 378 seismic data, 272 selecting, 11 semiarid, ix, 81, 117, 135, 136 sensing, viii, 35, 36, 37, 39, 40, 42, 45, 53, 54, 55, 61, 80 sensitivity, 17, 99, 103, 107, 109 separation, xi, 7, 161, 177, 193, 275, 279, 297, 327, 331, 334 series, viii, xi, 7, 35, 36, 38, 51, 61, 87, 100, 103, 120, 123, 125, 143, 154, 164, 171, 172, 173, 183, 200, 203, 205, 230, 232, 233, 275, 276, 315, 322, 324, 327, 328, 335, 341, 378, 381 services, iv shape, vii, xiii, 62, 98, 146, 155, 156, 173, 176, 349, 353, 354, 359, 362, 367, 370 shaping, 98, 102 shear, xi, 100, 119, 123, 124, 195, 235, 237, 241, 248, 251, 252, 253, 262, 266, 271, 320, 334, 335, 371, 375 shipping, 91, 92 shocks, 88 shores, 146, 279, 341 short period, 52, 162, 203 shortage, 161 short-range, 88 short-term, 92, 101, 197 shoulder, 347 shoulders, 248 SIB, 211, 212 Siberia, vii, ix, x, 90, 159, 160, 161, 162, 163, 165, 169, 173, 174, 175, 176, 177, 178, 179, 180, 181, 184, 185, 186, 187, 189, 190, 191, 192, 193, 195, 196, 197, 199, 209, 211, 216, 218, 219, 220, 221,

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

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396

Index

222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 378 sign, 169, 379 signals, 26, 265 significance level, 65 signs, xiii, 69, 80, 377, 378, 380, 381 similarity, 15, 176, 218, 247, 254, 278, 279, 285, 293, 297 simulation, ix, 117, 122, 126, 127, 128, 131, 135, 143, 151, 204, 216 simulations, 119, 123, 124, 153, 154, 155, 157 singular, viii, 88, 97, 100, 106, 108 sites, 11, 16, 17, 23, 62, 65, 67, 78, 79, 148, 153, 154, 155, 156, 167, 168, 171, 172, 201, 203, 204, 206, 208, 216, 218, 219, 360, 361 skeptics, 86 SLE, 118 Smithsonian, 309, 310 smoothness, 146 social behavior, 90 social change, 88 social isolation, 89 social systems, 89 socialist, 89 software, 41, 61, 62, 122, 124 soil, vii, ix, 1, 3, 18, 20, 21, 24, 25, 26, 39, 50, 86, 87, 93, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 128, 129, 130, 131, 132, 134, 135, 136, 137, 139, 142, 143, 144, 146, 147, 151, 152, 153, 154, 155 soil erosion, 118, 119, 120, 124, 134, 136, 137 soil particles, 123 soils, 50, 86, 106, 119, 120, 125, 126, 129, 134, 153, 155 solar, 6, 16, 63, 77, 78, 125, 356 sols, 153 Somali, 258 South Africa, 142 South America, 190, 331 South Asia, 270 Southeast Asia, 53, 54 sovereignty, 91 Spain, v, ix, 111, 117, 118, 119, 120, 136, 343 spatial, vii, viii, 1, 3, 15, 16, 19, 22, 25, 27, 40, 41, 42, 55, 57, 62, 63, 64, 78, 79, 81, 86, 91, 98, 103, 107, 113, 121, 123, 132, 135, 137, 139, 151, 178, 194, 199, 208 spatial analysis, 63 species, 86, 87, 88, 89, 279, 280, 281, 282, 283, 284, 285, 286, 287, 288, 289, 291, 293, 295, 298, 300, 301, 303, 304, 305 spectral analysis, 255, 262 spectrum, 36, 108, 240, 254, 256, 258, 259, 263, 265

speculation, 239 speed, 125, 239, 267, 270 sporadic, 200, 208 sports, 272 Sri Lanka, 254, 255, 266, 267, 268, 269, 271, 273 St. Petersburg, 357 stability, 92, 102, 107, 108, 114, 135, 256, 263 stabilization, 106, 213 stages, ix, 146, 147, 155, 159, 160, 182, 189, 208, 224, 246, 248 stakeholders, 91, 92 standard deviation, 144 standards, 105 stars, 186 statistical analysis, 63, 81 statistics, 20, 78, 152, 167, 168, 169, 171, 203, 206, 213, 217 steady state, 12, 20, 25, 109 stochastic, 123 Stochastic, 136 storage, 10, 18, 25, 61, 111, 115, 132 storms, 91, 103, 105, 111, 113, 114, 120, 129 strain, 222 strategies, 7, 8, 89 streams, 100, 110, 115, 116, 131 strength, 42, 108 stress, 89, 100, 119, 123, 124, 185, 198, 219, 222, 315, 319, 324, 326, 330, 331, 335, 337, 338, 343, 367 stretching, x, 160, 304 strikes, 180, 185 structural changes, 353, 354 structuring, 317, 318, 337 Styria, 374 subjective, 279 submarines, 92 subsistence, 51, 88 substrates, 350, 354, 356 subsurface flow, 119 subtraction, 379, 381 suburban, 51 suicide, 89 suicide rate, 89 summaries, 163 summer, 86, 87, 90, 105, 120, 142 superposition, 340 supply, 87, 128, 351, 353 surface area, 351, 352 surface water, 42, 154 surface wave, 240, 272 survival, 126, 301 susceptibility, 165, 250 sustainability, 94

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Index suture, 229, 248, 261, 262, 273 swamps, viii, 35, 51 swarm, 169, 177, 178, 226, 235, 272 swarms, 165, 179, 234 Sweden, 23 switching, 105 symbolic, 92 symbols, 5, 121 synchronous, 331, 343 synthesis, x, 113, 114, 160, 161, 230, 233, 236, 340 systematics, 305

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T taiga, 86 taxa, 286, 301 taxonomic, 279 temperature, xi, 17, 57, 60, 82, 86, 87, 93, 125, 166, 167, 169, 170, 172, 238, 265, 267, 278, 293 temporal, vii, ix, 1, 3, 7, 15, 16, 27, 87, 88, 97, 98, 99, 100, 102, 103, 105, 107, 141, 143 Tennessee, 1 tension, 316, 380 terraces, 24, 26, 49, 50, 51 territory, viii, xiii, 35, 36, 42, 51, 91, 160, 180, 197, 377, 378 Texas, 109, 277, 278, 280, 281, 282, 285, 286, 287, 288, 289, 291, 292, 293, 294, 298, 299, 300, 301, 303, 304, 306, 307, 308, 309, 310 Thailand, 39 thawing, 87, 88, 92 therapy, 353 thermal vibrations, 4 thermo-mechanical, 371 thin film, xiii, 345, 346, 354, 355, 356, 357 thin films, xiii, 345, 346, 354, 355, 356, 357 Thomson, 233 threats, 118 threshold, 36, 42, 43, 47, 48, 53, 129, 142 thresholds, 45, 99, 103, 114, 115, 116, 142 Tibet, 22, 24, 83, 240, 242, 245, 260, 261, 263, 268, 271, 272 timber, 136 time frame, 221 time series, 51, 143 timing, 15, 18, 86, 112, 227, 233, 334, 378 titanium, 92 Tokyo, 35 tolerance, 103, 139 topographic, 17, 18, 41, 42, 57, 63, 78, 80, 81, 137, 142, 154 topsoil, 144 total product, 5

397

trace elements, 370 tradition, 88 traditional model, 160 trajectory, 19, 329, 331 transfer, ix, xiii, 117, 132, 133, 345, 351 transference, ix, 117 transformation, x, 41, 110, 159, 221, 352, 356 transition, viii, 35, 62, 80, 86, 92, 122, 253, 262, 267, 315, 318, 330, 335, 365 transitions, 62 transparent, xiii, 345, 349, 354, 355, 356 transport, 2, 10, 18, 21, 27, 81, 89, 90, 98, 111, 115, 119, 124, 278, 309, 349, 353 transportation, 19, 25, 27 traps, 162, 175, 189, 195, 196, 197, 222, 226, 227, 228, 229, 232, 233, 235 travel, 272 travel time, 272 trees, 88 trial, 127 Triassic, vi, xii, xiii, 57, 162, 189, 191, 193, 195, 196, 197, 198, 199, 211, 218, 221, 222, 224, 225, 226, 227, 228, 232, 233, 235, 248, 287, 295, 301, 311, 312, 315, 316, 317, 318, 320, 321, 322, 323, 324, 326, 327, 328, 329, 330, 331, 332, 337, 340, 359, 360, 361, 362, 363, 364, 365, 366, 367, 370, 371, 372, 373, 374, 378 trust, 162 trusts, 232 tsunamis, 103 tuff, 183, 184, 189, 196, 200 tundra, 86 Tunisia, xii, 311, 312, 315, 318, 319, 322, 323, 324, 326, 327, 328, 331, 332, 337, 338, 341, 342, 343 turbulence, 124 two-dimensional, ix, 141, 143, 151, 346 typology, 138

U U.S. Department of Agriculture, 137 U.S. Geological Survey, 113, 337, 341 Ukraine, 345, 346 ultraviolet, 356 UN, 91 uncertainty, 15, 20, 89 uniform, 18, 20, 25, 124, 242 uniformitarianism, 100, 105 United States, 139, 305, 306, 308, 309 universality, 102 USDA, 124, 136, 137, 138, 139 USSR, 92, 196, 197, 224, 236 Utah, 309

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,

Index

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V

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vacuum, 356 validation, 47, 48, 49, 120, 136 validity, xi, 10, 135, 183, 263, 275 values, viii, ix, 12, 14, 26, 35, 36, 39, 41, 42, 47, 53, 62, 63, 67, 68, 80, 117, 119, 124, 125, 127, 128, 131, 132, 133, 134, 149, 153, 154, 156, 167, 169 variability, 81, 89, 99, 108, 112, 113, 132, 143 variables, ix, 100, 106, 117, 119, 126 variance, 69 variation, 6, 7, 16, 20, 26, 27, 112, 124, 156, 208, 322, 328, 349, 352 vector, 204, 208, 324, 326, 329, 331, 335, 336, 337 vegetation, 17, 18, 36, 42, 63, 81, 86, 93, 100, 106, 116, 124, 125, 126, 128 vein, 149 velocity, xi, 124, 192, 193, 219, 224, 238, 240, 247, 256, 258, 265, 267, 270, 272 versatility, 123 vessels, 39 victims, vii, 35, 36 Victoria, 82, 232 Vietnam, 36, 49, 51, 54 Vietnamese, 36, 49 village, 39, 91 violence, 89 visible, 317, 319, 326, 377 visualization, xiii, 345, 346, 349 volatility, 89 volcanic activity, xiii, 173, 197, 200, 208, 359, 360 vulnerability, viii, 35, 36, 114

W Wales, 112, 120 war, 265, 315 water, ix, 5, 15, 25, 37, 39, 42, 45, 50, 51, 87, 91, 118, 119, 122, 128, 136, 138, 141, 142, 148, 151, 152, 153, 154, 155, 156, 169, 182, 190, 279, 286, 293, 294, 295, 298, 301, 304, 305, 366, 367, 378

water table, ix, 141, 142, 151, 152, 153, 154, 155, 156 watershed, 2, 3, 10, 25, 26, 36, 111, 116, 122, 136, 137, 139, 156 watersheds, ix, 25, 26, 105, 110, 113, 117, 118, 130, 131, 136, 138 wave number, 255, 256, 259, 263, 264 weakness, 266, 278, 335 wealth, 88, 91, 92 wear, 355 weathering, vii, 1, 3, 22, 24, 25, 108, 111 weeping, 355 wells, 86 West Africa, 318 Western Europe, 118 Western Siberia, 235 wetlands, 87, 94, 153 wildfire, 114 wildfires, 105 wildlife, 89, 92, 346 wind, 20, 125 windows, 123, 378 winter, 112, 116 Wisconsin, 112 witnesses, 80 women, 353 woodland, 119 workers, 280 Wyoming, 16, 56, 83, 176, 227, 309

Y yield, ix, 23, 117, 118, 120, 122, 127, 128, 129, 130, 131, 132, 134, 135, 151, 153, 154 Yugoslavia, 374

Z Zn, 371 zoning, vii, 35, 36, 42, 53

Guiseppi, Antonio R.. Geomorphology and Plate Tectonics, edited by David M. Ferrari, and Antonio R. Guiseppi, Nova Science Publishers,