Exhumation Processes: Normal Faulting, Ductile Flow and Erosion Geological Society Special Publications Series Editors A. J. FLEET R. E. HOLDSWORTH A. C. MORTON M. S. STOKER It is recommended that reference to all or part of this book should be made in one of the following ways. RING, U., BRANDON,M. T., LISTER, G. S. & WlLLETT,S. D. (eds) 1999. Exhumation Processes: Normal Faulting, Ductile Flow and Erosion. Geological Society, London, Special Publications, 154. THOMSON, S. N., STOCKHERT,B. & BRIX, M. R. 1999. Miocene high-pressure metamorphic rocks of Crete, Greece: rapid exhumation by buoyant escape. In: RING, U., BRANDON, M. T., LISTER, G. S. & WILLETT, S. D. (eds) Exhumation Processes: Normal Faulting, Ductile Flow and Erosion. Geological Society, London, Special Publications, 154. GEOLOGICAL SOCIETY SPECIAL PUBLICATION NO. 154 Exhumation Processes: Normal Faulting, Ductile Flow and Erosion EDITED BY UWE RING (Johannes Gutenberg-Universitfit, Mainz, Germany) MARK T. BRANDON (Yale University, New Haven, USA) GORDON S. LISTER (Monash University, Clayton, Australia) and SEAN D. WILLETT (Pennsylvania State University, USA) 1999 Published by The Geological Society London THE GEOLOGICAL SOCIETY The Society was founded in 1807 as The Geological Society of London and is the oldest geological society in the world. It received its Royal Charter in 1825 for the purpose of 'investigating the mineral structure of the Earth'. The Society is Britain's national society for geology with a membership of around 8500. It has country- wide coverage and approximately 1500 members reside overseas. The Society is responsible for all aspects of the geological sciences including professional matters. The Society has its own publishing house, which pro- duces the Society's international journals, books and maps, and which acts as the European distributor for publications of the American Association of Petroleum Geologists, SEPM and the Geological Society of America. 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(918) 584-2555 Fax (918) 560-2652) First published 1999 Australia The publishers make no representation, express or Australian Mineral Foundation implied, with regard to the accuracy of the 63 Conyngham Street information contained in this book and cannot Glenside accept any legal responsibility for any errors or South Australia 5065 omissions that may be made. Australia (Orders: Tel. (08) 379-0444 © The Geological Society 1998. All rights reserved. Fax (08) 379--4634) No reproduction, copy or transmission of this publication may be made without written permission. India No paragraph of this publication may be reproduced, Affiliated East-West Press PVT Ltd copied or transmitted save with the provisions of the G-l/16 Ansari Road Copyright Licensing Agency, 90 Tottenham Court New Delhi 110 002 Road, London WlP 9HE. Users registered with the India Copyright Clearance Center, 27 Congress Street, (Orders: Tel. (11) 327-9113 Salem, MA 01970, USA: the item-fee code for this Fax (11) 326-0538) publication is 0305-8719/98/$10.00. Japan British Library Cataloguing in Publication Data Kanda Book Trading Co. A catalogue record for this book is available from Cityhouse Tama 204 the British Library. Tsurumaki 1-3-10 Tama-Shi ISBN 1-86239-025-8 Tokyo 206-0034 Japan Typeset by Type Study, Scarborough, UK (Orders: Tel. (0423) 57-7650 Fax (0423) 57-7651) Printed in Great Britain by Cambridge University Press, Cambridge, UK. Contents Preface vii Acknowledgements viii RING, g., BRANDON, M. T., WILLETE, S. D. & LISTER, G. S. Exhumation Processes 1 Subduction-related accretionary wedges (B-type subduction) SEDLOCK, R. L. Evaluation of exhumation mechanisms for coherent blueschists in 29 western Baja California, Mexico RING, U. & BRANDON, M. T. Ductile deformation and mass loss in the Franciscan 55 Subduction Complex: implications for exhumation processes in accretionary wedges THOMSON, S. N., STOCKHERT, B. & BRIX, M. R. Miocene high-pressure metamorphic rocks 87 of Crete, Greece: rapid exhumation by buoyant escape RAWLING,T. J. & LISTER, G. S. Oscillating modes of orogeny in the Southwest Pacific 109 and the tectonic evolution of New Caledonia WINTSCH, R. P., BYRNE, T. & TORIUMI, M. Exhumation of the Sanbagawa blueschist belt, 129 SW Japan, by lateral flow and extrusion: evidence from structural kinematics and retrograde P-T-t paths Collisional belts and intra-continental convergence (A-type subduction) SCHLUNEGGER,E • WILLETT,S. Spatial and temporal variations in exhumation of the 157 central Swiss Alps and implications for exhumation mechanisms VANDERHAEGHE, O., BURG, J.-P. & TEYSSIER, C. Exhumation of migmatites in two collapsed 181 orogens: Canadian Cordillera and French Variscides CALVERT, A. W., GANS, P. B. & AMATO, J. M. Diapiric ascent and cooling of a sillimanite 205 gneiss dome revealed by 40Ar/39Ar thermochronology: the Kigluaik Mountains, Seward Peninsula, Alaska GLAZNER, A. E Exposure of deep, dense rocks: interplay between erosion and sinking 233 MILLER, J. McL., GREGORY, R. T., GRAY, D. R. & FOSTER, D. A. Geological and 241 geochronological constraints on the exhumation of a high-pressure metamorphic terrane, Oman BATT, G. E., KOHN, B. P., BRAUN, J., McDOUGALL, I. & IRELAND,T. R. New insight into the 261 dynamic development of the Southern Alps, New Zealand, from detailed thermochronological investigation of the Mataketake Range pegmatites GARVER, J. I., BRANDON, M. T., RODEN-TICE, M. & KAMP, P. J. J. Exhumation history of 283 orogenic highlands determined by detrital fission-track thermochronology Lithospberic extension: divergent plate motions (rifting) FORSTER, M. A. & LISTER, G. S. Detachment faults in the Aegean core complex of Ios, 305 Cyclades, Greece vi CONTENTS GOODWIN, L. B. Controls on pseudotachylyte formation during tectonic exhumation in 325 the South Mountains metamorphic core complex, Arizona FOSTER, D. A. & JOHN, B. E. Quantifying tectonic exhumation in an extensional orogen 343 with thermochronology: examples from the southern Basin and Range Province Preface The general idea of this book is to provide an overview of exhumation processes. The idea was conceived dur- ing a conference on the same topic. The papers were organized to provide a broad sampling of frontier research on all processes that contribute to exhumation of metamorphic rocks in ancient and modern orogens. Examples from a variety of tectonic settings, including continental rifts, oceanic subduction zones and continental collision zones are given. The papers provide innovative applications of structural geology, metamorphic petrology and thermochronology to resolve the rates and geometry of normal faulting, and the interaction between erosion and tectonics. One of the weaknesses of the volume is that the role that surface processes play in the exhuma- tion of deeply seated rocks is not well presented. The volume contains 16 papers. The opening contribution by Ring et aL is a review aimed at providing an umbrella for the more focused papers that follow. The remaining papers are arranged into three sections, divid- ed according to tectonic setting. The first section, Subduction-related accretionary wedges (B-type subduction), starts with studies of the Franciscan subduction complex by Sedlock and Ring & Brandon. Sedlock documents normal faulting as the primary exhumation mechanism for blueschists in Baja California. Ring & Brandon examine the role of deformation, primarily ductile flow in tectonically exhuming the high-grade Eastern Franciscan Belt, and show that these processes played only a minor role. The papers of Thomson et al. and Rawling & Lister are examples of dominantly normal-faulting-controlled exhumation at retreating subduction zones. The contribution of Wintsch et aL calls for margin-parallel shear as the principal exhumation process for Cretaceous high-pressure metamorphic rocks at the Japan convergent margin. The second section is Collisional belts and intra-conthzental convergence (A-type subduction). The first three papers address the exhumation of high-temperature rocks in the internides of collisional orogens. The paper of Schlunegger & Willett examines how exhumation influenced the postcollisional growth and destruction of the Alps. The paper illustrates how difficult it is to distinguish between tectonic exhumation and erosion. Vanderhaeghe et al. also highlight the interplay between various exhumation mechanisms during the destruc- tion of the migmatitic core in two collisional orogens. Calvert et al. report on an interesting example of exhuma- tion by diapirism. Glazner reviews how magmatism might influence extensional deformation. The paper focus-