ENCYCLOPEDIA OF

GEOLOGY

ENCYCLOPEDIA OF

GEOLOGYEDITED BY

RICHARD C. SELLEY L. ROBIN M. COCKS IAN R. PLIMER

ELSEVIERACADEMIC PRESS Amsterdam Boston Heidelberg London New York Oxford Paris San Diego San Francisco Singapore Sydney Tokyo

Elsevier Ltd., The Boulevard, Langford Lane, Kidlington, Oxford, OX5 1GB, UK 2005 Elsevier Ltd. The following articles are 2005, The Natural History Museum, London, UK: FOSSIL VERTEBRATES/Hominids Palaeontology PALAEOZOIC/Silurian PRECAMBRIAN/Overview Terranes, Overview Conservation of Geological Specimens MINERALS/Olivines MINERALS/Sulphates TERTIARY TO PRESENT/Pleistocene and The Ice Age Environmental Geochemistry Biological Radiations and Speciation PALAEOZOIC/Ordovician TERTIARY TO PRESENT/Eocene TERTIARY TO PRESENT/Paleocene FOSSIL PLANTS/Angiosperms FOSSIL PLANTS/Gymnosperms Biozones MESOZOIC/Cretaceous MESOZOIC/End Cretaceous Extinctions Stratigraphical Principles FOSSIL INVERTEBRATES/Molluscs Overview FOSSIL INVERTEBRATES/Trilobites FOSSIL INVERTEBRATES/Echinoderms (Other Than Echinoids) FOSSIL INVERTEBRATES/Echinoids TERTIARY TO PRESENT/Pliocene FOSSIL INVERTEBRATES/Bryozoans MINERALS/Feldspathoids Russia The following article is a US Government work in the public domain and not subject to copyright: NORTH AMERICA/Atlantic Margin "Earth from Space" endpaper figure reproduced with permission from Reto Stockli, Nazmi El Saleous, and Marit Jentoft-Nilsen and NASA GSFC All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publishers. Permissions may be sought directly from Elsevier's Rights Department in Oxford, UK: phone (+44) 1865 843830, fax (+44) 1865 853333, e-mailpermissions@elsevier.com. Requests may also be completed on-line via the homepage (http://www.elsevier.com/locate/permissions). First edition 2005 Library of Congress Control Number: 2004104445 A catalogue record for this book is available from the British Library ISBN 0-12-636380-3 (set) This book is printed on acid-free paper Printed and bound in Spain

EDITORS v

Editors

EDITORSRichard C. Selley

Imperial College London, UKL. Robin M. Cocks

Natural History Museum London, UKIan R. Plimer

University of Melbourne Melbourne, VA Australia

CONSULTANT EDITORJoe McCall

Cirencester Gloucestershire, UK

vi EDITORIAL ADVISORY BOARD

Editorial Advisory BoardJaroslav Aichler Georg Hoinkes

Czech Geological Survey Jesen k, Czech RepublicAndrew R Armour

t Graz Universita tplatz 2 Universita Graz, AustriaR A Howie

Revus Energy A/S NorwayJohn Collinson

Royal Holloway, London University London, UKShunsho Ishihara

Delos, Beech Staffordshire, UKAlexander M Davis

Geological Survey of Japan Tsukuba, JapanGilbert Kelling

Infoscape Solutions Ltd. Guildford, UKPeter Doyle

Keele University Keele, UKKen Macdonald

University College London London, UKWolfgang Franke

University of California Santa Barbara Santa Barbara, CA, USANorman MacLeod

Institut fu r Geowissenschaften Giessen, GermanyYves Fuchs

The Natural History Museum London, UKStuart Marsh

Marne la Valle Universite FrancePaul Garrard

British Geological Survey Nottingham, UKJoe McCall

Cirencester, Gloucestershire, UKDavid R Oldroyd

Formerly Imperial College London, UKR O Greiling

University of New South Wales Sydney, NSW, AustraliaRong Jia-yu

t Heidelberg Universita Heidelberg, GermanyGwendy Hall

Nanjing Institute of Geology and Palaeontology Nanjing, ChinaMike Rosenbaum

Natural Resources Canada Ottawa, ON, CanadaRobert D Hatcher, Jr.

Twickenham, UKPeter Styles

University of Tennessee Knoxville, TN, USA

Keele University Keele, UK

EDITORIAL ADVISORY BOARD vii

Hans D Sues

S H White

Carnegie Museum of Natural History Pittsburgh, PA, USAJohn Veevers

Universiteit Utrecht Utrecht, The Netherlands

Macquarie University Sydney, NSW, Australia

FOREWORD ix

ForewordFew areas of science can have changed as fast as geology has in the past forty years. In the first half of the last century geologists were divided, often bitterly, between the drifters and those who believed that the Earth and its continents were static. Neither side of this debate foresaw that the application of methods from physics, chemistry and mathematics to these speculations would revolutionize the study of all aspects of the Earth Sciences, and would lead to accurate and detailed reconstructions of world geography at former times, as well as to an understanding of the origin of the forces that maintain the continental movements. This change in world-view is no longer controversial, and is now embedded in every aspect of the Earth Sciences. It is a real pleasure to see this change, which has revitalized so many classic areas of research, reflected in the articles of this encyclopedia. Particularly affected are the articles on large-scale Earth processes, which discuss many of the new geological ideas that have come from geophysics and geochemistry. Forty years ago we had no understanding of these topics, which are fundamental to so many aspects of the Earth Sciences. The editors have decided, and in my view quite rightly, not to include detailed discussion of the present technology that is used to make geophysical and geochemical measurements. Such instrumental aspects are changing rapidly and become dated very quickly. They can easily be found in more technical publications. Instead the editors have concentrated on the influence such studies have had on our understanding of the Earth and its evolution, and in so doing have produced an excellent and accessible account of what is now known. Any encyclopedia has to satisfy a wide variety of users, and in particular those who know that some subject like sedimentation or mineral exploration is part of geology, and go to an encyclopedia of geology to find out more. The editors have made a very thorough attempt to satisfy such users, and have included sections on such unexpected geological topics as the evolution of the Earths atmosphere, the geology of Jupiter, Saturn, and their moons, aggregates, and creationism. I congratulate the editors and authors for producing such a fine summary of our present knowledge, and am particularly pleased that they intend to produce an online version of the encyclopedia. Though I have become addicted to using the Internet as my general encyclopedia, I will be delighted to be able to access something concerned with my own field that is as organized and scholarly as are these volumes.Dan McKenzie Royal Society Professor of Earth Sciences Cambridge University, UK

INTRODUCTION xi

IntroductionCivilization occurs by geological consent subject to change without notice.... Will Durant (1885 1981)

Richard de Bury, Bishop of Durham from 1333 to 1345, divided all knowledge into Geologia, earthly knowledge, and Theologia, heavenly knowledge. By the beginning of the last century, however, Geology was generally understood to be restricted to the study of rocks: according to the old dictum of the Geological Survey of Great Britain If you can hit it with a hammer, then its geology. Subsequently geology has been subsumed into Earth Science. This includes not only the study of rocks (the lithosphere), but also the atmosphere and hydrosphere and their relationship with the biosphere. Presently these relationships now form a nexus in Earth System Science. The Encyclopedia of Geology is what it says on the cover. What appealed to us when first approached to edit this work by Academic Press was a request that the encyclopedia should be rock-based. Readers are referred to the companion volumes, Encyclopedia of Atmospheric Sciences, Encyclopedia of the Solar System, Encyclopedia of Soils in the Environment and Encyclopedia of Ocean Sciences for knowledge on the other branches of Earth Science. Nonetheless we have extended our brief to include articles on the other planets and rocky detritus of our solar system, leaving others to argue, as no doubt Bishop Richard would have done, where the boundaries of earthly and heavenly knowledge might be. (His Grace would probably have charged the editors of the Encyclopedia of the Solar System with heresy.) One of the first, and most difficult, tasks of editing this encyclopedia was to decide, not only which topics merited articles, but also how these articles should be grouped to facilitate the reader. This is easy for some branches of geology, but difficult for others. It is relatively easy to logically arrange articles on mineralogy and palaeontology, since they are defined by their chemistry and evolutionary biology. Articles that describe Earth history may be conveniently arranged in a chronological order, and articles on regional geology may be presented geographically. Other topics present problems, particularly in the area of sedimentology. There is, for example, a range of inter-related topics associated with deserts. This area could be described geomorphologically, and in terms of the aeolian and aqueous processes of deserts, aeolian sedimentary structures, and aeolian deposits. All of these aspects of deserts deserve mention, but there is no obvious logical way of arranging the discrete topics into articles. To help us in this task we relied heavily on our editorial board, whose individual members had more specialized knowledge of their field than we. To the Editorial Board Members, authors and anonymous referees of each article we give heartfelt thanks. We were also, of course, constrained by the willingness of expert authorities to contribute articles. To some degree therefore, the shape of the encylopedia owes as much to the enthusiasm of experts to write for us, as for our wish list of articles. To facilitate readers finding their way around the Encyclopedia of Geology great care has been taken in crossreferencing within and between articles, in providing See Also lists at the end of articles, and in the index. No doubt it will be easier for readers to navigate around the online version of the work, than to manipulate the several hard copy volumes. As geological knowledge expands there is always more to learn and understand. While preparing the Encyclopedia of Geology we have ourselves learned a great deal about geology, both within and beyond our own specialties. We invite you to read this encyclopedia and join us in the field trip of a lifetime. Richard C. Selley L. Robin M. Cocks Ian R. Plimer 1 August 2004 References to related encyclopedia published by Elsevier, Academic Press: Encyclopedia of the Solar System, 1998 Encyclopedia of Ocean Sciences, 2001 Encyclopedia of Atmospheric Sciences, 2002 Encyclopedia of Soils in the Environment, 2005

GUIDE TO USE OF THE ENCYCLOPEDIA xiii

Guide to Use of the EncyclopediaStructure of the EncyclopediaThe material in the Encyclopedia is arranged as a series of entries in alphabetical order. Most entries consist of several articles that deal with various aspects of a topic and are arranged in a logical sequence within an entry. Some entries comprise a single article. To help you realize the full potential of the material in the Encyclopedia we have provided three features to help you find the topic of your choice: a Contents List, Cross-References and an Index.

1. Contents ListYour first point of reference will probably be the contents list. The complete contents lists, which appears at the front of each volume will provide you with both the volume number and the page number of the entry. On the opening page of an entry a contents list is provided so that the full details of the articles within the entry are immediately available. Alternatively you may choose to browse through a volume using the alphabetical order of the entries as your guide. To assist you in identifying your location within the Encyclopedia a running headline indicates the current entry and the current article within that entry. You will find 'dummy entries' where obvious synonyms exist for entries or where we have grouped together related topics. Dummy entries appear in both the contents lists and the body of the text. Example If you were attempting to locate material on erosional sedimentary structures via the contents list: EROSION see SEDIMENTARY PROCESSES: Fluxes and Budgets; Aeolian Processes; Erosional Sedimentary Structures. The dummy entry directs you to the Erosional Sedimentary Structures article, in the SEDIMENTARY PROCESSES entry. At the appropriate location in the contents list, the page numbers for articles under Sedimentary Processes are given. If you were trying to locate the material by browsing through the text and you looked up Erosion then the following information would be provided in the dummy entry:

EROSIONSee SEDIMENTARY PROCESSES: Erosional Sedimentary Structures; Aeolian Processes; Fluxes and Budgets

xiv

GUIDE TO USE OF THE ENCYCLOPEDIA

Alternatively, if you were looking up Sedimentary Processes the following information would be provided:

SEDIMENTARY PROCESSESContents Erosional Sedimentary Structures Depositional Sedimentary Structures Post-Depositional Sedimentary Structures Aeolian Processes Catastrophic Floods Deep Water Processes and Deposits Fluvial Geomorphology Glaciers Karst and Palaeokarst Landslides Particle-Driven Subaqueous Gravity Processes Deposition from Suspension Fluxes and Budgets

2. Cross-ReferencesAll of the articles in the Encyclopedia have been extensively cross-referenced. The cross-references, which appear at the end of an article, serve three different functions. For example, at the end of the PRECAM BRIAN: Overview article, cross-references are used: i. To indicate if a topic is discussed in greater detail elsewhere. Africa: Pan-African Orogeny. Antarctic Asia: Central. Australia: Proterozoic Biosediments and Biofilms Earth Structure and Origins. Earth System Science.Europe: East European Craton; Timanides of Northern Russia. Gondwanaland and Gondwana. Grenvillian Orogeny. Indian Subcontinent. North America:Precambrian Continental Nucleus; Continental Interior. Precambrian: Eukaryote Fossils; Prokaryote Fossils; Vendian and Ediacaran, Russia, Sedimentary Rocks: Banded Iron Formations. Shields. Terranes, Overview.ii. To draw the reader's attention to parrallel discussions in other articles.

Africa: Pan-African Orogeny. Antarctic. Asia: Central. Australia: Proterozoic. Biosediments and Biofilms. Earth Structure and Origins. Earth System Science. Europe: East European Craton; Timanides of Northern Russia. Gondwanaland and Gondwana. Grenvillian Orogeny Indian Subcontinent. North America: Precambrian Continental Nucleus; Continental Interior. Precambrian: Eukaryote Fossils; Prokaryote Fossils; Vendian and Ediacdran. Russia. Sedimentary Rocks: Banded Iron Formations. Shields. Terranes, Overview.

GUIDE TO USE OF THE ENCYCLOPEDIA xv

iii. To indicate material that broadens the discussion. Africa: Pan-African Orogeny. Antarctic. Asia: Central. Australia: Proterozoic. Biosediments and Biofilms. Earth Structure and Origins. Earth Syatem Science. Europe: East European Graton; Timanides of Northern Russia. Gondwantand and Gendwana. Grenvillian Orogeny. Indian Subcontinent. North America: Precambrian Continental Nucleus; Continental Interior. Precambrian: Eukaryote Fossils; Prokaryote Fossils; Vendian and Ediacaran. Russia. Sedimentary Rocks: Banded Iron Formations. Shields. Terranes, Overview.

3. IndexThe index will provide you with the page number where the material is located, and the index entries differentiate between material that is a whole article, is part of an article or is data presented in a figure or table. Detailed notes are provided on the opening page of the index.

4. ContributorsA full list of contributors appears at the beginning of each volume.

CONTRIBUTORS xvii

ContributorsAbart, R University of Basel, Basel, Switzerland Aldridge, R J University of Leicester, Leicester, UK Al-Jallal, I A Sandroses Est. for Geological, Geophysical Petroleum Engineering Consultancy and Petroleum Services, Khobar, Saudi Arabia Alkmim, F F Universidade Federal de Ouro Preto, Ouro Preto, Brazil Allen, P M Bingham, Nottingham, UK Allwood, A C Macquarie University, Sydney, NSW, Australia Al-Sharhan, A S United Arab Emirates University, AI-Ain, United Arab Emirates Anderson, L I National Museums of Scotland, Edinburgh, UK Arndt, N T LCEA, Grenoble, France Arnott, R Oxford Institute for Energy Studies, Oxford, UK Asimow, P D California Institute of Technology, Pasadena, CA, USA Atkinson, J City University, London, UK Bacon, M Petro-Canada, London, UK Bailey, J Anglo-Australian Observatory and Australian Centre for Astrobiology, Sydney, Australia Bani, P Institut de la Recherche pour le Dveloppement, Noumea, New Caledonia Bell, F G British Geological Survey, Keyworth, UK Bell, K Carleton University, Ottawa, ON, Canada Best, J University of Leeds, Leeds, UK Birch, W D Museum Victoria, Melbourne, VIC, Australia Bird, J F Imperial College London, London, UK Black, P Auckland University, Auckland, New Zealand Bleeker, W Geological Survey of Canada, Ottawa, ON, Canada Bogdanova, S V Lund University, Lund, Sweden Bommer, J J Imperial College London, London, UK Boore, D M United States Geological Survey, Menlo Park, CA, USA Bosence, D W J Royal Holloway, University of London, Egham, UK Boulanger, R W University of California, Davis, CA, USA Braga, J C University of Granada, Granada, Spain Branagan, D F University of Sydney, Sydney, NSW, Australia Brasier, M D University of Oxford, Oxford, UK Brewer, P A University of Wales, Aberystwyth, UK Bridge, M University College London, London, UK Brown, D Institute de Ciencias de la Tierra 'Jaume Almera' CSIC, Barcelona, Spain Brown, A J Macquarie University, Sydney, NSW, Australia Brown, R J University of Bristol, Bristol, UK

xviii CONTRIBUTORS Bucher, K University of Freiburg, Freiburg, Germany Burns, S F Portland State University, Portland, OR, USA Byford, E Broken Hill, NSW, Australia Calder, E S Open University, Milton Keynes, UK Cameron, E M Eion Cameron Geochemical Inc., Ottawa, ON, Canada Carbotte, S M Columbia University, New York, NY, USA Carminati, E Universita La Sapienza, Rome, Italy Chamberlain, S A Macquarie University, Sydney, NSW, Australia Charles, J A Formerly Building Research Establishment Hertfordshire, UK Chiappe, L M Natural History Museum of Los Angeles County Los Angeles, CA, USA Clack, J A University of Cambridge, Cambridge, UK Clayton, C Eardiston, Tenbury Wells, UK Clayton, G Trinity College, Dublin, Ireland Cocks, L R M The Natural History Museum, London, UK Coffin, M F University of Tokyo, Tokyo, Japan Collinson, J John Collinson Consulting, Beech, UK Comerford, G The Natural History Museum, London, UK Condie, K C New Mexico Tech, Socorro, NM, USA Cornford, C Integrated Geochemical Interpretation Ltd, Bideford, UK Cornish, L The Natural History Museum, London, UK

Cosgrove, J W Imperial College London, London, UK Coxon, P Trinity College, Dublin, Ireland Cressey, G The Natural History Museum, London, UK Cribb, S J Carraig Associates, Inverness, UK Cronan, D S Imperial College London, London, UK Currant, A The Natural History Museum, London, UK Davies, H University of Papua New Guinea, Port Moresby Papua New Guinea Davis, G R Imperial College London, London, UK DeCarli, P S SRI International, Menlo Park, CA, USA Dewey, J F University of California Davis Davis, CA, USA, and University of Oxford, Oxford, UK Doglioni, C Universita La Sapienza, Rome, Italy Doming, K J University of Sheffield, Sheffield, UK Dott, Jr R H University of Wisconsin, Madison, Wl, USA Doyle, P University College London, London, UK Dubbin, W E The Natural History Museum, London, UK Dyke, G J University College Dublin, Dublin, Ireland Echtler, H GeoForschungsZentrum Potsdam, Potsdam, Germany Eden, M A Geomaterials Research Services Ltd, Basildon, UK Eide, E A Geological Survey of Norway, Trondheim, Norway Eldholm, O University of Bergen, Bergen, Norway

CONTRIBUTORS xix

Elliott, D K Northern Arizona University, Flagstaff, AZ, USA Elliott, T University of Liverpool, Liverpool, UK Eriksen, A S Zetica, Witney, UK Payers, S R University of Aberdeen, Aberdeen, UK Feenstra, A GeoForschungsZentrum Potsdam, Potsdam, Germany Felix, M University of Leeds, Leeds, UK Figueras, D BFI, Houston, TX, USA Fookes, P G Winchester, UK Forey, P L The Natural History Museum, London, UK Fortey, R A The Natural History Museum, London, UK Foster, D A University of Florida, Gainesville, FL, USA Frda, J Czech Geological Survey, Prague, Czech Republic Franke, W Johann Wolfgang Goethe-Universitat Frankfurt am Main, Germany Franz, G Technische Universitat Berlin, Berlin, Germany French, W J Geomaterials Research Services Ltd, Basildon, UK Fritscher, B Munich University, Munich, Germany Frostick, L University of Hull, Hull, UK Fuchs, Y Universit Marne la Valle, Marne la Valle, France Gabbott, S E University of Leicester, Leicester, UK Garaebiti, E Department of Geology and Mines, Port Vila, Vanuatu

Garetsky, R G Institute of Geological Sciences, Minsk, Belarus Garrard, P Imperial College London, London, UK Gascoyne, J K Zetica, Witney, UK

Gee, D G University of Uppsala, Uppsala, SwedenGeshi, N Geological Survey of Japan, Ibaraki, Japan Giese, P Freie Universitat Berlin, Berlin, Germany Giles, D P University of Portsmouth, Portsmouth, UK Glasser, N F University of Wales, Aberystwyth, UK Gluyas, J Acorn Oil and Gas Ltd., Staines, UK Gorbatschev, R Lund University, Lund, Sweden Gordon, J E Scottish Natural Heritage, Edinburgh, UK Gradstein, F M University of Oslo, Oslo, Norway Gray, D R University of Melbourne, Melbourne, VIC, Australia Greenwood, J R Nottingham Trent University, Nottingham, UK Grieve, RAF Natural Resources Canada, Ottawa, ON, Canada Griffiths, J S University of Plymouth, Plymouth, UK Hambrey, M J University of Wales, Aberystwyth, UK Hancock, J M Formerly Imperial College London, London, UK Hansen, J M Danish Research Agency, Copenhagen, Denmark Harff, J Baltic Sea Research Institute Warnemunde, Rostock, Germany

Deceased

xx

CONTRIBUTORS

Harper, DAT Geologisk Museum, Copenhagen, Denmark Harper, E M University of Cambridge, Cambridge, UK Harrison, JP Imperial College London, London, UK Hatcher, Jr RD University of Tennessee, Knoxville, TN, USA Hatheway, A W Rolla, MO and Big Arm, MT, USA Hauzenberger, C A University of Graz, Graz, Austria Hawkins, A B Charlotte House, Bristol, UK Haymon, R M University of California-Santa Barbara Santa Barbara, CA, USA He Guoqi Peking University, Beijing, China Head, J W Brown University, Providence, Rl, USA Heim, N A University of Georgia, Athens, GA, USA Helvaci, C Dokuz Eyll niversitesi, Izmir, Turkey Hendriks, B W H Geological Survey of Norway, Trondheim, Norway Henk, A Universitt Freiburg, Freiburg, Germany Herries Davies, G L University of Dublin, Dublin, IrelandHey, R N University of Hawaii at Manoa, Honolulu, HI, USA

Howell, J University of Bergen, Bergen, Norway Howie, R A Royal Holloway, University of London, London, UK Hudson-Edwards, K University of London, London, UK Huggett, J M Petroclays, Ashtead, UK and The Natural History Museum, London, UK Hughes, N C University of California, Riverside, CA, USA Hutchinson, D R US Geological Survey, Woods Hole, MA, USA Idriss, I M University of California, Davis, CA, USA Ineson, J R Geological Survey of Denmark and Greenland Geocenter Copenhagen, Copenhagen, Denmark Ivanov, M A Russian Academy of Sciences, Moscow, Russia Jger, K D Martin Luther University, Halle, Germany Jarzembowski, E A University of Reading, Reading, UK and Maidstone Museum and Bentlif Art Gallery, Maidstone, UK Jones, B University of Alberta, Edmonton, AB, Canada Jones, G L Conodate Geology, Dublin, Ireland Joyner, L Cardiff University, Cardiff, UK Kaminski, M A University College London, London, UK

Hoinkes, G University of Graz, Graz, Austria Hooker, J J The Natural History Museum, London, UK Home, D J University of London, London, UK Hovland, M Statoil, Stavanger, Norway

Kay, S MCornell University, Ithaca, NY, USA Kemp, A I S University of Bristol, Bristol, UK Kendall, A C University of East Anglia, Norwich, UK Kenrick, P The Natural History Museum, London, UK

CONTRIBUTORS xxi

Kogiso, T Japan Marine Science and Technology Center, Yokosuka, Japan Krings, M Bayerische Staatssammlung fr Palontologie und Geologic, Geo-Bio Center, Munich, Germany Lancaster, N Desert Research Institute, Reno, NV, and United States Geological Survey, Reston, VA, USA Lang,K R Tufts University, Medford, MA, USA Laurent, G Brest, France

MacLeod, N The Natural History Museum, London, UK Maltman, A University of Wales, Aberystwyth, UK Martill, D M University of Portsmouth, Portsmouth, UK Martins-Neto, M A Universidade Federal de Ouro Preto, Ouro Preto, Brazil Marvin, U B Harvard-Smithsonian Center for Astrophysics Cambridge, MA, USA Mason, P J HME Partnership, Romford, UK Massonne, H-J Universitt Stuttgart, Stuttgart, Germany Matte, P University of Montpellier II, Montpellier, France Mayor, A Princeton, USA McCaffrey, W University of Leeds, Leeds, UK McCall, G J H Cirencester, Gloucester, UK McCave, I N University of Cambridge, Cambridge, UK McGhee, G R Rutgers University, New Brunswick, NJ, USA McKibben, M A University of California, CA, USA McLaughlin, Jr P P Delaware Geological Society, Newark, DE, USA McManus, J University of St. Andrews, St. Andrews, UK McMenamin, MAS Mount Holyoke College, South Hadley, MA, USA Merriam, D F University of Kansas, Lawrence, KS, USA Metcalfe, I University of New England, Armidale, NSW, Australia Milke, R University of Basel, Basel, Switzerland

Lee, E M York, UKLemke, W Baltic Sea Research Institute Warnemnde, Rostock Germany Lesher, C M Laurentian University, ON, Canada Lewin, J University of Wales, Aberystwyth, UKLiu, J G Imperial College London, London, UK

Long,J A The Western Australian Museum, Perth WA, Australia Loock, J C University of the Free State Bloemfontein, South Africa Lowell, R P Georgia Institute of Technology, Atlanta, GA, USA Lucas, S G New Mexico Museum of Natural History Albuquerque, NM, USA Liming, S University of Bremen, Bremen, GermanyLuo, Z-X Carnegie Museum of Natural History Pittsburgh, PA, USA

Macdonald, K C University of California-Santa Barbara Santa Barbara, CA, USA Machel, H G University of Alberta, Edmonton, Alberta, Canada

xxii CONTRIBUTORS

Milner, A R Birkbeck College, London, UK Mojzsis, S J University of Colorado, Boulder, CO, USA Monger, J W H Geological Survey of Canada, Vancouver, BC, Canada and Simon Fraser University Burnaby, BC, Canada Moore, P Selsey, UK

Oneacre, J W BFI, Houston, TX, USA Orchard, M J Geological Survey of Canada Vancouver, BC, Canada

Orr, P JUniversity College Dublin, Dublin, Ireland Owen, A W University of Glasgow, Glasgow, UK Plike, H Stockholm University, Stockholm, Sweden Page, K N University of Plymouth, Plymouth, UK Paris, F University of Rennes 1, Rennes, France Parker, J R Formerly Shell EP International, London, UK Pfiffner, O A University of Bern, Bern, Switzerland Piper, D J W Geological Survey of Canada, Dartmouth, NS, Canada Price, R A Queens University Kingston, ON, Canada Prothero, D R Occidental College, Los Angeles, CA, USA Puche-Riart, O Polytechnic University of Madrid, Madrid, Spain

Morris, N JThe Natural History Museum, London, UK Mortimer, N Institute of Geological and Nuclear Sciences, Dunedin New Zealand Mountney, N P Keele University, Keele, UK Mpodozis, C SIPETROL SA, Santiago, Chile Mungall, J E University of Toronto, Toronto, ON, Canada Myrow, P Colorado College, Colorado Springs, CO, USA Naish, D University of Portsmouth, Portsmouth, UK Nickel, E H CSIRO Exploration and Mining, Wembley, WA, Australia Nielsen, K C The University of Texas at Dallas, Richardson, TX, USA Nikishin, A M Lomonosov Moscow State University, Moscow, Russia Nokleberg, W J United States Geological Survey, Menlo Park, CA, USA Norbury, D CL Associates, Wokingham, UK O'Brien, P J Universitt Potsdam, Potsdam, GermanyOgg, J G Purdue University, West Lafayette, IN, USA

Pye, KRoyal Holloway, University of London, Egham, UK Rahn, P H South Dakota School of Mines and Technology Rapid City, SD, USA Ramos, V A Universidad de Buenos Aires, Buenos Aires, Argentina Rankin, A H Kingston University, Kingston-upon-Thames, UK Rebesco, M Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Italy Reedman, A J Mapperley, UK

Oldershaw, C St. Albans, UK Oldroyd, D R University of New South Wales, Sydney, Australia

CONTRIBUTORS xxiii

Reisz, R R University of Toronto at Mississauga Mississauga, ON, Canada Retallack, G J University of Oregon, Eugene, OR, USA Rickards, R B University of Cambridge, Cambridge, UK Riding, R Cardiff University, Cardiff, UK Rigby, J K Brigham Young University, Provo, UT, USA Rigby, S University of Edinburgh, Edinburgh, UK Rodda, P Mineral Resources Department, Suva, Fiji Rona, P A Rutgers University, New Brunswick, NJ, USA Rose, E P F Royal Holloway, University of London, Egham, UK Rosenbaum, M S Twickenham, UK Rothwell, R G Southampton Oceanography Centre, Southampton, UKRoy, A B Presidency College, Kolkata, India

Searle, R C University of Durham, Durham, UK Seibold, I University Library, Freiburg, Germany Selley, R C Imperial College London, London, UK Sellwood, B W University of Reading, Reading, UK Shields, G A James Cook University, Townsville, OLD, Australia Simms, M J Ulster Museum, Belfast, UK Slipper, I J University of Greenwich, Chatham Maritime, UK Smallwood, J R Amerada Hess pic, London, UK Smith, A B The Natural History Museum, London, UK Smith, I Auckland University, Auckland, New Zealand Snoke, A W University of Wyoming, Laramie, WY, USA Soligo, C The Natural History Museum, London, UK Stein, S Northwestern University, Evanston, IL, USA Steinberger, B Japan Marine Science and Technology Center Yokosuka, Japan Stemmerik, L Geological Survey of Denmark and Greenland, Geocenter Copenhagen, Copenhagen, Denmark Stern, R J The University of Texas at Dallas, Richardson, TX, USA Stewart, I University of Plymouth, Plymouth, UK Storey, B C University of Canterbury, Christchurch, New Zealand Storrs, G W Cincinnati Museum Center, Museum of Natural History and Science, Cincinnati, OH, USA

Rushton, A W A The Natural History Museum, London, UK Russell, A J University of Newcastle upon Tyne, Newcastle upon Tyne, UK Schmid, R ETH-centre, Zurich, Switzerland Scott, E National Center for Science Education Berkeley, CA, USA Scon, A C Royal Holloway, University of London, Egham, UK Scrutton, C T Formerly University of Durham, Durham, UK Searle, M University of Oxford, Oxford, UK

xxiv

CONTRIBUTORS

Strachan, R A University of Portsmouth, Portsmouth, UK Suetsugu, D Japan Marine Science and Technology Center, Yokosuka Japan Surlyk, F University of Copenhagen, Geocenter Copenhagen, Copenhagen, Denmark Tait, J Ludwig-Maximilians-Universitt, Mnchen, Germany Talbot, M R University of Bergen, Bergen, Norway Taylor, P D The Natural History Museum, London, UK Taylor, T N University of Kansas, Lawrence, KS, USA Taylor, W E G University of Lancaster, Lancaster, UK Tazawa, J Niigata University, Niigata, Japan Theodor, J M Illinois State Museum, Springfield, IL, USA Timmerman, M J Universitt Potsdam, Potsdam, Germany Tollo, R P George Washington University, Washington, DC, USA Torsvik, T H Geological Survey of Norway, Trondheim, Norway Trendall, A Curtin University of Technology, Perth, Australia Trewin, N H University of Aberdeen, Aberdeen, UK Turner, A K Colorado School of Mines, Colorado, USA Twitchett, R J University of Plymouth, Plymouth, UK Tyler, I M Geological Survey of Western Australia East Perth, WA, Australia Valdes, P J University of Bristol, Bristol, UK

van Geuns, L C Clingendael International Energy Programme The Hague, The Netherlands van Staal, C R Geological Survey of Canada, Ottawa, ON, Canada Vanecek, M Charles University Prague, Prague, Czech Republic Vaughan,D J University of Manchester, Manchester, UK Veevers, J J Macquarie University, Sydney, NSW, Australia Verniers, J University of Ghent, Ghent, Belgium Wadge, G University of Reading, Reading, UK Walter, M R Macquarie University, Sydney, NSW, Australia Wang, H China University of Geosciences, Beijing, China Ware, N G Australian National University, Canberra, ACT, Australia Warke, P A Queen's University Belfast, Belfast, UK Weber, K J Technical University, Delft, The Netherlands Welch, M D The Natural History Museum, London, UK Westbrook, G K University of Birmingham, Birmingham, UK Westermann, G E G McMaster University, Hamilton, ON, Canada Whalley, W B Queen's University Belfast, Belfast, UK White, N C Brisbane, OLD, Australia White, S M University of South Carolina, Columbia, SC, USA Wignall, P B University of Leeds, Leeds, UK Williams, P A University of Western Sydney, Parramata, Australia

CONTRIBUTORS xxv

Wise, W S University of California-Santa Barbara Santa Barbara, CA, USA Worden, R H University of Liverpool, Liverpool, UK Wyatt, A R Sidmouth, UK Xiao, S Virginia Polytechnic Institute and State University Blacksburg, VA, USA

Yakubchuk, A S The Natural History Museum, London, UK Yates, A M University of the Witwatersrand, Johannesburg South Africa Zhang Shihong China University of Geosciences, Beijing, China Ziegler, P A University of Basel, Basel, Switzerland

CONTENTS xxvii

ContentsVolume 1AAFRICA Pan-African Orogeny A Krner, R J Stern North African Phanerozoic S Lning Rift Valley L Frostick AGGREGATES M A Eden, W J French ALPS See EUROPE: The Alps ANALYTICAL METHODS Fission Track Analysis B W H Hendriks Geochemical Analysis (Including X-ray) R H Warden Geochronological Techniques E A Eide Gravity / R Smallwood Mineral Analysis N G Ware ANDES S M Kay, C Mpodozis, V A Ramos B C Storey / A Al-Jallal, A S Al-Sharhan VA Ramos ANTARCTIC ARGENTINA43 54 77 92 107 118 132 140 153 164 169

1 12 2634

ARABIA AND THE GULF ASIA Central S G Lucas South-East / Metcalfe

ASTEROIDS See SOLAR SYSTEM: Asteroids, Comets and Space Dust ATMOSPHERE EVOLUTION S J Mojzsis197 208 222 237

AUSTRALIA Proterozoic / M Tyler Phanerozoic J J Veevers Tasman Orogenic Belt D R Gray, D A Foster

BBIBLICAL GEOLOGY BIODIVERSITY E Byford P L Forey253 259 266 279 294 306 328

A W Owen M R Walter, A C Allwood

BIOLOGICAL RADIATIONS AND SPECIATION BIOSEDIMENTS AND BIOFILMS BIOZONES BRAZIL N MacLeod F F Alkmim, M A Martins-Neto A W Hatheway

BUILDING STONE

xxviii

CONTENTS

cCALEDONIDE OROGENY See EUROPE: Caledonides Britain and Ireland; Scandinavian Caledonides (with Greenland) CARBON CYCLE CLAY MINERALS G A Shields H Wang, Shihong Zhang, Guoqi He Y Fuchs / M Huggett 335 345 358 366 370 L Cornish, G Comerford 373 381 CHINA AND MONGOLIA CLAYS, ECONOMIC USES COLONIAL SURVEYS

COCCOLITHS See CALCAREOUS ALGAE A J Reedman COMETS See SOLAR SYSTEM: Asteroids, Comets and Space Dust CONSERVATION OF GEOLOGICAL SPECIMENS CREATIONISM E Scott

DDELTAS See SEDIMENTARY ENVIRONMENTS: Deltas DENDROCHRONOLOGY DIAGENESIS, OVERVIEW M Bridge R C Selley 387 393 DESERTS See SEDIMENTARY ENVIRONMENTS: Deserts DINOSAURS See FOSSIL VERTEBRATES: Dinosaurs

EEARTH Mantle GJH McCall 397

Crust

GJHMcCallH Palike GJH McCall

403410 421 430

Orbital Variation (Including Milankovitch Cycles) EARTH STRUCTURE AND ORIGINS EARTH SYSTEM SCIENCE R C Selley

EARTHQUAKES See ENGINEERING GEOLOGY: Aspects of Earthquakes; TECTONICS: Earthquakes ECONOMIC GEOLOGY G R Davis 434 444 448 456 463 474 482 499 515 525 535

ENGINEERING GEOLOGY Overview M S Rosenbaum Codes of Practice D Nor bury Aspects of Earthquakes A W Hatheway Geological Maps / S Griffiths Geomorphology M Lee, J S Griffiths, P G Fookes Geophysics / K Gascoyne, A S Eriksen Seismology J J Bommer, D M Boore Natural and Anthropogenic Geohazards G J H McCall Liquefaction / F Bird, R W Boulanger, IM Idriss Made Ground / A Charles

CONTENTS xxix

Problematic Rocks F G Bell Problematic Soils F G Bell Rock Properties and Their Assessment F G Bell Site and Ground Investigation / R Greenwood

543 554 566 580

Volume 2ENGINEERING GEOLOGY Site Classification A W Hatheway Subsidence A B Hawkins Ground Water Monitoring at Solid Waste Landfills ENVIRONMENTAL GEOCHEMISTRY ENVIRONMENTAL GEOLOGY W E Dubbin

/ W Oneacre, D Figueras

1 9 14 21 25

P Doyle

EROSION See SEDIMENTARY PROCESSES: Erosional Sedimentary Structures; Aeolian Processes; Fluxes and Budgets EUROPE East European Craton R G Garetsky, S V Bogdanova, R Gorbatschev Timanides of Northern Russia D G Gee Caledonides of Britain and Ireland R A Strachan , J F Dewey Scandinavian Caledonides (with Greenland) D G Gee Variscan Orogeny W Franke, P Matte, J Tait The Urals D Brown, H Echtler Permian Basins A Henk, M J Timmerman Permian to Recent Evolution PA Ziegler The Alps O AP fiffner Mediterranean Tectonics Carminati, C Doglioni Holocent W Lemke, J HarffA EVOLUTION S Rigby, E MEharper 34 49 56 64 75 86 95 102 125 135 147 160

FFAKEFOSSILS D I Martill 169 174 179 184 188

FAMOUS GEOLOGISTS Agassiz D R Oldroyd Cuvier G Laurent Darwin D R Oldroyd Du Toit / C Loock, D F Branagan

Hall R H Dott, JrHutton D R Oldroyd Lyell D R Oldroyd Murchison D R Oldroyd Sedgwick D R Oldroyd Smith D R Oldroyd Steno / M Hansen Suess B Fritscher Walther I Seibold Wegener B Fritscher FLUID INCLUSIONS A H Rankin

194200 206 210 216 221 226 233 242 246 253

xxx

CONTENTS

FORENSIC GEOLOGY

K Pye

261 274 281 295 301 310 321 334 342 350 357 367 369 378 389 396 408 418 428 436 443 454 462 468 479 490 497 502 508 516 523 527 535 541

FOSSIL INVERTEBRATES Arthropods LI Anderson Trilobites A WA Rushton Insects E A Jarzembowski Brachiopods D AT Harper Bryozoans P D Taylor Corals and Other Cnidaria C T Scrutton Echinoderms (Other Than Echinoids) A B Smith Crinoids M / Simms Echinoids A B Smith Graptolites R B Richards Molluscs Overview N J Morris Bivalves E M Harper Gastropods / Fry da Cephalopods (Other Than Ammonites) P Doyle Ammonites G E G Westermann Porifera / K Rigby FOSSIL PLANTS Angiosperms P Kenrick Calcareous Algae / C Braga, R Riding Fungi and Lichens T N Taylor, M Krings Gymnosperms P Kenrick FOSSIL VERTEBRATES Jawless Fish-Like Vertebrates D K Elliott Fish / A Long Palaeozoic Non-Amniote Tetrapods / A Clack Reptiles Other Than Dinosaurs R R Reisz Dinosaurs A M Yates Birds G / Dyke, L M Chiappe Swimming Reptiles G W Storrs Flying Reptiles D Naish, D M Martill Mesozoic Amphibians and Other Non-Amniote Tetrapods Cenozoic Amphibians A R Milner Mesozoic Mammals Z-X Luo Placental Mammals D R Prothero Hominids L R M Cocks

A R Milner

Volume 3

GGAIA GJHMcCallC Oldershaw L Joyner M Cameron / E Gordon A K Turner

16 14 21 29 35

GEMSTONES

GEOARCHAEOLOGY

GEOCHEMICAL EXPLORATION GEOLOGICAL CONSERVATION GEOLOGICAL ENGINEERING

CONTENTS xxxi

GEOLOGICAL FIELD MAPPING GEOLOGICAL SOCIETIES GEOLOGICAL SURVEYS GEOLOGY OF BEER GEOLOGY OF WHISKY GEOMORPHOLOGY GEOMYTHOLOGY

P Canard A Maltman

43 53 60 65 73 78 82 85 90 96

GEOLOGICAL MAPS AND THEIR INTERPRETATION G L Merries Davies P M Allen G L Jones

GEOLOGY, THE PROFESSION S J Cribb

S J Cribb P H Rahn

GEOLOGY OF WINE / M Hancock 85 A Mayor

GEOPHYSICS See EARTH: Orbital Variation (Including Milankovitch Cycles); EARTH SYSTEM SCIENCE; ENGINEERING GEOLOGY: Seismology; MAGNETOSTRATIGRAPHY; MOHO DISCONTINUITY; PALAEOMAGNETISM; PETROLEUM GEOLOGY: Exploration; REMOTE SENSING: Active Sensors; CIS; Passive Sensors; SEISMIC SURVEYS; TECTONICS: Seismic Structure at Mid-Ocean Ridges GEOTECHNICAL ENGINEERING GEYSERS AND HOT SPRINGS GOLD MAMcKibben J J Veevers D P Giles G J H McCall 100 105 118 128 155

GLACIERS See SEDIMENTARY PROCESSES: Glaciers GONDWANALAND AND GONDWANA GRANITE See IGNEOUS ROCKS: Granite GRENVILLIAN OROGENY R P Tollo

HHERCYNIAN OROGENY See EUROPE: Variscan Orogeny HIMALAYAS See INDIAN SUBCONTINENT HISTORY OF GEOLOGY UP TO 1780 O Puche-Riart D R Oldroyd D R Oldroyd D F Branagan 167 173 179 185 197 HISTORY OF GEOLOGY FROM 1780 TO 1835 HISTORY OF GEOLOGY FROM 1835 TO 1900 HISTORY OF GEOLOGY FROM 1900 TO 1962 HISTORY OF GEOLOGY SINCE 1962I

U B Marvin

IGNEOUS PROCESSES IGNEOUS ROCKS Carbonatites K Bell Granite AIS KempDeceased

P D Asimow

209 217 233

xxxii

CONTENTS

Kimberlite Komatiite Obsidian

GJH McCall N TArndt, C M Lesher G / H McCall RAF Grieve A B Roy

247 260 267 277 285

IMPACT STRUCTURES INDIAN SUBCONTINENT

JJAPAN / Tazawa 297 JUPITER See SOLAR SYSTEM: Jupiter, Saturn and Their Moons

LLAGERSTTTEN S E Gabbott M F Coffin, O Eldholm 307 315 323

LARGE IGNEOUS PROVINCES LAVA N Geshi

MMAGNETOSTRATIGRAPHY S G Lucas D Suetsugu, T Kogiso, B Steinberger 331 335

MANTLE PLUMES AND HOT SPOTS MARS See SOLAR SYSTEM: Mars MERCURY See SOLAR SYSTEM: Mercury

MESOZOIC Triassic S G Lucas, M J Orchard Jurassic K N Page Cretaceous N MacLeod End Cretaceous Extinctions N MacLeod METAMORPHIC ROCKS Classification, Nomenclature and Formation Facies and Zones K Bucher PTt-Paths PJ O'Brien METEORITES See SOLAR SYSTEM: Meteorites MICROFOSSILS Acritarchs K J Doming Chitinozoa F Paris, J Verniers Conodonts R J Aldridge Foraminifera M A Kaminski Ostracoda D / Home Palynology P Coxon, G Clayton MICROPALAEONTOLOGICAL TECHNIQUES I J Slipper 470 MILANKOVITCH CYCLES See EARTH: Orbital Variation (Including Milankovitch Cycles) MILITARY GEOLOGY EPF Rose G R Davis G Hoinkes, C A Hauzenberger, R Schmid

344 352 360 372 386 402 409

418 428 440 448 453 464 470

475 488

MINERAL DEPOSITS AND THEIR GENESIS

CONTENTS xxxiii

MINERALS Definition and Classification E H Nickel 498 Amphiboles R A Howie Arsenates K Hudson-Edwards 506 Borates C Helvaci Carbonates B Jones Chromates PA Williams Feldspars R A Howie Feldspathoids M D Welch Glauconites J M Huggett 542 Micas R A Howie Molybdates P A Williams Native Elements P A Williams Nitrates PA Williams Olivines G Cressey, R A Howie Other Silicates R A Howie Phosphates See SEDIMENTARY ROCKS: Phosphates Pyroxenes R A Howie Quartz R A Howie Sulphates G Cressey Sulphides D J Vaughan Tungstates P A Williams Vanadates P A Williams Zeolites W S Wise Zircons G J H McCall MINING GEOLOGY Exploration Boreholes M Vanecek Exploration N C White Mineral Reserves M Vanecek Hydrothermal Ores M A McKibben Magmatic Ores / Mungall MOHO DISCONTINUITY P Giese

498 503 506 510 522 532 534 539542

548 551 553 555 557 561 567 569 572 574 586 588 591 601 609 613 623 628 637 645

MOON See SOLAR SYSTEM: Moon

Volume 4

NNEW ZEALAND N Mortimer NORTH AMERICA Precambrian Continental Nucleus W Bleeker Continental Interior D F Merriam Northern Cordillera J W H Monger, R A Price, W J Nokleberg 36 Southern Cordillera AWSnoke Ouachitas K C Nielsen Southern and Central Appalachians R D Hatcher, Jr Northern Appalachians C R van Staal Atlantic Margin D R Hutchinson1

8 21 36 48 61 72 81 92

xxxiv CONTENTS

oOCEANIA (INCLUDING FIJI, PNG AND SOLOMONS) I Smith, E Garaebiti, P Rodda ORIGIN OF LIFE / Bailey H Davies, P Bani, P Black, 109 123

pPALAEOCLIMATES PALAEOMAGNETISM PALAEONTOLOGY PALAEOPATHOLOGY B W Sellwood, P J Valdes T H Torsvik L R M Cocks S G Lucas 131 140 147 156 160 163 175 184 194 200 214 219 225 229 248 261268

PALAEOECOLOGY E M Harper, S Rigby

PALAEOZOIC Cambrian N C Hughes, N A Heim Ordovician R A Fortey Silurian L R M Cocks Devonian G R McGhee Carboniferous A C Scott Permian P B Wignall End Permian Extinctions RJ Twitchett PANGAEA S G Lucas PETROLEUM GEOLOGY Overview / Gluyas Chemical and Physical Properties C Clayton Gas Hydrates M Hovland The Petroleum System C Cornford 268 Exploration / R Parker Production KJ Weber, L C van Geuns Reserves R Arnott PLATE TECTONICS R C Searle PRECAMBRIAN Overview L R M Cocks Eukaryote Fossils S Xiao Prokaryote Fossils M D Brasier Vendian and Ediacaran MAS McMenamin 371 PSEUDOFOSSILS PYROCLASTICS D M Martill R J Brown, E S Calder

295 308 331 340 350 354 363371

382 386

QQUARRYING A W Hatheway 399

RREEFS See SEDIMENTARY ENVIRONMENTS: Reefs ("Build-Ups") REGIONAL METAMORPHISM A Feenstra, G Franz 407

CONTENTS xxxv

REMOTE SENSING Active Sensors G Wadge CIS P J Mason Passive Sensors / G Liu RIFT VALLEYS See AFRICA: Rift Valley ROCK MECHANICS JP Harrison R C Selley

414 420 431 440 452 456

ROCKS AND THEIR CLASSIFICATION RUSSIA A S Yakubchuk, A M Nikishin

sSATURN See SOLAR SYSTEM: Jupiter, Saturn and Their Moons SEAMOUNTS S M White 475 485 492 495 501 513 528 539 550 562 570 580 587 593 602 612 628 641 650 663 678 687

SEDIMENTARY ENVIRONMENTS Depositional Systems and Fades J Collinson Alluvial Fans, Alluvial Sediments and Settings K D Jger Anoxic Environments P B Wignall Carbonate Shorelines and Shelves D W J Bosence Contourites M Rebesco Deltas T Elliott Deserts N P Mountney Lake Processes and Deposits M R Talbot Reefs ('Build-Ups') B W Sellwood Shoreline and Shoreface Deposits J How ell Storms and Storm Deposits P Myrow SEDIMENTARY PROCESSES Erosional Sedimentary Structures J Collinson Depositional Sedimentary Structures / Collinson Post-Depositional Sedimentary Structures / Collinson Aeolian Processes N Lancaster Catastrophic Floods A J Russell Deep Water Processes and Deposits D J W Piper Fluvial Geomorphology / Lewin, P A Brewer Glaciers M / Hambrey, N F Glasser Karst and Palaeokarst M J Simms Landslides S F Burns

Volume 5SEDIMENTARY PROCESSES Particle-Driven Subaqueous Gravity Processes M Felix, W McCaffrey 1 Deposition from Suspension IN McCave Fluxes and Budgets L Frostick SEDIMENTARY ROCKS Mineralogy and Classification R C Selley Banded Iron Formations A Trendall Chalk / R Ineson, L Stemmerik, F Surlyk Chert N H Trewin, S R Payers

1 8 17 25 37 42 51

xxxvi CONTENTS

Clays and Their Diagenesis / M Huggett Deep Ocean Pelagic Oozes R G Rothwell Dolomites H G Machel Evaporites A C Kendall Ironstones W E G Taylor Limestones R C Selley Oceanic Manganese Deposits D S Cronan Phosphates W D Birch Rudaceous Rocks / McManus Sandstones, Diagenesis and Porosity Evolution SEISMIC SURVEYS M Bacon

J

Gluyas

62 70 79 94 97 107 113 120 129 141151

SEQUENCE STRATIGRAPHY SHIELDS K C Condie

P P Mclaughlin, Jr

159 173 179 184 194 203 209 220 228 238 244 264 272 282 289 295

SHOCK METAMORPHISM P S DeCarli SOIL MECHANICS / Atkinson SOILS Modern Palaeosols G J Retallack G J Retallack

SOLAR SYSTEM The Sun K R Lang Asteroids, Comets and Space Dust P Moore Meteorites G J H McCall Mercury G J H McCall Venus M A Ivanov, J W Head Moon P Moore Mars M R Walter, A J Brown, S A Chamberlain Jupiter, Saturn and Their Moons P Moore Neptune, Pluto and Uranus P Moore SPACE DUST See SOLAR SYSTEM: Asteroids, Comets and Space Dust STRATIGRAPHICAL PRINCIPLES N MacLeod

STROMATOLITES See BIOSEDIMENTS AND BIOFILMS SUN See SOLAR SYSTEM: The Sun

TTECTONICS Convergent Plate Boundaries and Accretionary Wedges G K Westbrook Earthquakes G J H McCall Faults S Stein Folding / W Cosgrove Fractures (Including Joints) / W Cosgrove Hydrothermal Activity R P Lowell, P A Rona Mid-Ocean Ridges K C Macdonald Hydrothermal Vents At Mid-Ocean Ridges R M Haymon Propagating Rifts and Microplates At Mid-Ocean Ridges R N Hey Seismic Structure At Mid-Ocean Ridges S M Carbotte Mountain Building and Orogeny M Searle Neotectonics I Stewart 307 318 330 339 352 362 372 388 396 405 417 425

CONTENTS xxxvii

Ocean Trenches R J Stern Rift Valleys L Frostick TEKTITES G J H McCall L R M Cocks TERRANES OVERVIEW

428 437 443 455459

TERTIARY TO PRESENT Paleocene J J Hooker 459 Eocene / / Hooker Oligocene D R Prothero Miocene J M Theodor 478 Pliocene C Soligo Pleistocene and The Ice Age THERMAL METAMORPHISM TIME SCALE TRACE FOSSILS

466 472478

A Currant R Abart, R Milke

486 493 499 503 520

F M Gradstein, J G Ogg P J Orr

uULTRA HIGH PRESSURE METAMORPHISM H-J Massonne 533 UNCONFORMITIES A R Wyatt / Best 533 541 548 557

UNIDIRECTIONAL AQUEOUS FLOW URALS See EUROPE: The Urals URBAN GEOLOGY A W Hatheway 557

VVENUS See SOLAR SYSTEM: Venus VOLCANOES G J H McCall 565

WWEATHERING W B Whalley, P A Warke 5 81

Index

591

NEW ZEALAND 1

NEW ZEALANDN Mortimer, Institute of Geological and Nuclear Sciences, Dunedin, New Zealand 2005, Elsevier Ltd. All Rights Reserved.

IntroductionThe south-west Pacific Ocean is a region of isolated islands and submerged plateaus and ridges (Figure 1). The three main islands of New Zealand (North, South, and Stewart) make up the largest landmass group in the region. Schists, greywackes, and granitoids are exposed in islands on the Challenger Plateau and Chatham Rise and have been sampled in dredges on the Campbell Plateau and Norfolk Ridge, thus demonstrating their continental geological character. Abyssal Pacific oceanic-crustal floor typically lies at water depths of about 5000 m, and the boundary between continental crust and oceanic crust is marked by a generally pronounced slope break at about 2500 m water depth. The wider area of continental crust in the New Zealand region (Figure 1) is about one-third the area of on-land Australia and is commonly referred to as Zealandia. On-land New Zealand contains a wide variety of Phanerozoic rocks (Figure 2), which preserve a detailed record of the Cambrian to early Early Cretaceous convergent margin of southern Gondwana, late Early Cretaceous rifting, a Late Cretaceous Palaeogene passive margin, and the NeogeneHolocene active convergent and strike-slip margin. So much of continental Zealandia is submerged because of the widespread Cretaceous extension and rifting. It was only with the development of the NeogeneHolocene convergent plate boundary that about 10% of Zealandia emerged above sea-level. A distinction is generally drawn in New Zealand between pre-late Early Cretaceous (more than 105 Ma) basement rocks, which are commonly metamorphosed and generally highly deformed, and cover rocks, which are younger than 105 Ma, poorly indurated, well stratified, and less deformed.

tectonic events. Reconstructions (Figure 3) involve subtracting the 480 km Neogene dextral strike-slip movement on the Alpine Fault, the 45 Oligocene Miocene rotation between the Pacific and Australian plates, and 4000 km of northwards drift. Small crustal blocks within 100 km of the Alpine Fault (i.e. most of on-land New Zealand) have undergone strong Cenozoic deformation. In the pre-rift (100 Ma) palaeogeography (Figure 3A) Zealandia is in a near-polar position and contiguous with Tasmania and Antarctica. By 10 Ma, some movement on the Alpine Fault had taken place and modern-day New Zealand had been isolated by seafloor spreading.

Geological BasementAt a regional scale, the volcanic, sedimentary, plutonic, and metamorphic basement rocks of New Zealand can be described in terms of a number of western and eastern tectonostratigraphic terranes, composite regional batholiths intruding these terranes, and schist, gneiss, and me lange overprints on

Palaeogeographical ReconstructionsThe shape of the continental crust of Zealandia has changed throughout the Phanerozoic. From the Cambrian to the Early Cretaceous, the New Zealand part of the Gondwanan margin grew by the magmatic and tectonic addition of batholiths and terranes. In the last 100 Ma this continental crust has been thinned, rotated, and translated in response to multipleFigure 1 The outline of the area of continental crust in the New Zealand region (Zealandia). Land and major islands are pale brown; water less than 2500 m deep is pale blue. Deep ocean floor is dark blue and Hikurangi plateau large igneous province is intermediate blue. The present day Pacific Australian plate boundary is shown by the thick black line, with teeth on the over riding plate. Only about 10% of Zealandia is emergent above sea level as the North and South Islands. NR, Norfolk Ridge.

2 NEW ZEALAND

Figure 2 Simplified present day on land geology of New Zealand. The black lines are faults. Many of the lakes and valleys of the South Island are the result of Quaternary glacial erosion. G, locations of Devonian to Jurassic Gondwanan sequences; , locations of Cretaceous metamorphic core complexes.

the terranes and batholiths (Figure 4). Figure 5 shows the names, age ranges, and mutual geometric relationships of the constituent basement units on an Early Cretaceous reconstruction (Figure 3A). No Precambrian rocks are exposed; New Zealand has been near a continentocean margin throughout the Phanerozoic.Western Province Terranes

The Western Province terranes lie west of the Median Batholith and comprise the Early Palaeozoic Buller and Takaka terranes. The Buller Terrane consists of variably metamorphosed siliciclastic sandstones and mudstones, of continental Gondwanan provenance, and is the westernmost recognized terrane in New Zealand (i.e. the terrane closest to the Gondwanan cratonic core). Rare fossils are of Ordovician age, but

a Buller Terrane paragneiss contains detrital zircons as old as 3400 Ma (Archean; New Zealands oldest known geological material). Intercalated volcanics are absent. The Takaka Terrane consists of siliciclastic, carbonate, and volcanic rocks. Middle Cambrian trilobites in the Takaka Terrane are New Zealands oldest known fossils. The Takaka Terrane is generally well stratified and lithologically diverse, and includes Cambrian ultramafics and boninites, Ordovician limestones, and Silurian orthoquartzites. The Buller and Takaka Terranes were accreted to Gondwana by the Devonian.Eastern Province Terranes

The Eastern Province terranes lie east of the Median Batholith and comprise the Brook Street, Murihiku,

NEW ZEALAND 3

Figure 3 Palaeogeographical reconstructions of New Zealand at approximately (A) 100 Ma, (B) 65 Ma, (C) 30 Ma, and (D) 10 Ma. Brown, inferred land including schematic island arc chains; black lines, present day coastlines of North and South Islands and the Alpine Fault. On these reconstructions, the Alpine fault divides the South Island into eastern and western parts. (Reproduced with permission from Lee DE, Lee WG, and Mortimer N (2001) Where and why have all the flowers gone? Depletion and turnover in the New Zealand Cenozoic angiosperm flora in relation to palaeogeography and climate. Australian Journal of Botany 49: 341 356.)

Maitai, Caples, Rakaia, and Pahau terranes. Carboniferous conodonts are known from a limestone in the Rakaia Terrane, but the age range of clastic rocks in Eastern Province terranes is from Permian to Early Cretaceous (Figure 5). The Eastern Province terranes are thus entirely younger than the Western Province terranes and represent accretion of material to Gondwana in the Mesozoic. The Brook Street Terrane is a Permian subductionrelated isotopically primitive pyroxene-rich basaltdominated volcanic pile and volcaniclastic apron, in places up to 14 km thick, which is intruded by Permian layered gabbros and trondhjemite plutons that are now part of the Median Batholith. New Zealands only known Glossopteris, a Gondwanan leaf fossil, occurs in the Brook Street Terrane. The Murihiku Terrane comprises a 913 km Late Permian to Late Jurassic volcaniclastic marine succession of sandstone with lesser conglomerates, mudstones, and tuffs. It has the simplest internal structure of all the Mesozoic New Zealand terranes, a broad synclinorium that is

traceable for 450 km through the North and South Islands. The Maitai Terrane consists of the eastern Early Permian (285275 Ma, according to uraniumlead dating of zircon) Dun Mountain Ophiolite Belt, which is unconformably overlain by 6 km of wellstratified Late Permian to Middle Triassic volcaniclastic sedimentary rocks. The ophiolite originated in a near-arc setting. The Brook Street, Murihiku and Maitai terranes are adjacent to each other as a PermianTriassic arc, fore-arc, and exhumed near-arc ophiolite, respectively. The Caples, Bay of Islands, and Rakaia terranes contrast with the aforementioned Eastern Province terranes in that their PermianJurassic clastic sequences are tectonically imbricated with ocean-floor basalt, chert, and limestone associations; all three terranes grade into the pumpellyiteactinolite to amphibolite facies Haast Schist. Deposition occurred as submarine-fan deposits in lower trench-slope basins, before juxtaposition in an accretionary

4 NEW ZEALAND

Figure 4 Basement geological subdivisions of New Zealand. Minor outliers of Permian Gondwanan sequences rest on Takaka Terrane, and Devonian, Triassic and Jurassic Gondwanan sequences on Buller Terrane. DMOB, Dun Mountain Ophiolite Belt. (Reproduced with permission from Mortimer N (2004) New Zealands geological foundations. Gondwana Research 7: 261 272. International Association for Gondwana Research.)

prism. Compositional and provenance differences are used to discriminate the three terranes: Rakaia sandstones are quartz rich, plutoniclastic, and of average rhyodacitic composition and are thus compositionally distinct from the more dacitic to andesitic volcaniclastic-dominated sandstones in Caples and the Bay of Islands. The Pahau Terrane has a similar lithology

and structure to the Rakaia Terrane, but its depositional ages extend into the Late Jurassic and Early Cretaceous and it contains tuffs. Much of the Pahau clastic detritus is probably recycled from Rakaia rocks, but a volcanic input, probably from the Median Batholith, is also required. The Pahau Terrane probably represents trench deposits that

NEW ZEALAND 5

Figure 5 (A) Summary of the age ranges of New Zealands basement terranes (green, blue, brown, yellow), batholiths (red, orange), and metamorphic rocks (overprint stripes). Gondwana Sequence rocks are shown by letters: K, Kirwans Dolerite; T, Topfer Formation; P, Parapara Group; R, Reefton Group. The terranes can be grouped into Eastern and Western provinces. (B) One possible palaeogeo graphical reconstruction of south eastern Gondwana at about 120 Ma (the end of the convergent margin phase). The present day New Zealand coastlines are shown as white lines; the Alpine Fault and other faults are shown as white dotted lines. (Reproduced with permission from Mortimer N (2004) New Zealands geological foundations. Gondwana Research 7: 261 272. International Association for Gondwana Research.)

were laid down and deformed towards the end of Cretaceous subduction. These nine terranes make up the bulk of the New Zealand volcanosedimentary basement. Smaller tectonostratigraphic units can be regarded as components of the larger terranes. The Median Tectonic Zone is still used by some New Zealand geologists to describe a zone of terrane shards and igneous complexes of uncertain status and correlation that lies between the Brook Street and Takaka terranes (see Plutonic Rocks, below).Overlap Sequences

Overlap sequences of varying ages can be recognized by their lesser deformation and metamorphism and

distinctive petrofacies, as compared with older immediately underlying rocks. Lateral correlatives are used to constrain models of terrane amalgamation and accretion. The only New Zealand rocks that have been correlated with autochthonous Gondwanan sequences occur in two small outliers in northern South Island (marked G in Figure 2). Four units the Reefton Group (marine Devonian), Parapara Group (marine PermianTriassic), Topfer Formation (nonmarine Triassic), and Kirwans Dolerite (a Middle Jurassic low-titanium tholeiite sill intrusion) indicate that the Buller and Takaka terranes had been accreted to Gondwana by the end of the Palaeozoic. In North Island, a postulated Late Jurassic overlap sequence the Waipa Supergroup, possibly sourced

6 NEW ZEALAND

from the Median Batholith may indicate that most of the basement terranes had accreted by this time. The post-105 Ma cover sediments provide a firm minimum age for the mutual juxtaposition and accretion of the basement terranes.Plutonic Rocks

There are three composite regional batholith-sized belts (more than 100 km2) of plutons in New Zealand, and numerous smaller isolated plutons. The Median Batholith is a composite Cordilleran batholith with intrusive contacts against the Brook Street and Takaka terranes. It comprises dozens of 110 km Carboniferous to Early Cretaceous gabbroic to granitic subalkaline I-type plutons. The eastern half of the Median Batholith has also been called the Median Tectonic Zone. The ages and average compositions of the rocks change across the batholith axis: Permian gabbroids dominate the eastern edge, Triassic to early Early Cretaceous dioritoids dominate the central part, and late Early Cretaceous adakitic granitoids are found on the western margin. Roof pendants of petrologically related volcanosedimentary rocks occupy about 5% of the batholith area. How much of the Median Batholith is allochthonous is debatable. The KarameaPaparoa Batholith lies entirely within the Buller Terrane. Its constituent plutons are dominated by DevonianCarboniferous I-type and S-type granites. The Hohonu Batholith, also within the Buller Terrane, represents 10582 Ma plutonism associated with the change from convergence to rifting.Metamorphic Overprints

of the accretionary wedge. The steep me langes may represent zones of strike-slip deformation. Episodes of tectonic activity were previously described as orogenies. In the early 1980s it was realized that the Mesozoic Rangitata Orogeny was probably a composite of an older subduction-related event and a younger extension-related event. With the recognition that much of the intrusion, metamorphism, and deformation in the Buller and Takaka terranes (Tuhua Orogen) occurred during the Cretaceous (of Rangitata age), the orogen terminology became obsolete.

Cover StrataLate Early Cretaceous to Holocene rocks rest unconformably on all the older basement units. The last 100 Ma of New Zealands geological history can conveniently be divided into four periods, which are discussed in the following sections.Late Early Cretaceous Intracontinental Rifting

Regionally extensive metamorphic overprints include Devonian and Cretaceous polymetamorphic amphibolitegranulite facies gneisses (formed from Buller, Takaka, Median, and KarameaPaparoa protoliths). Some of the gneisses are confined to the lower plates of two Cretaceous metamorphic core complexes in the South Island (stars in Figure 2). The Haast Schist of JurassicCretaceous pumpellyiteactinolite to amphibolite facies overprints the Caples, Bay of Islands, and Rakaia terranes. Metamorphism probably took place in the deep parts of a JurassicEarly Cretaceous accretionary wedge. Exhumation of the Haast Schist belt was episodic, with most of the schist being at the surface by 105 Ma and deeper levels being exhumed along the Alpine Fault from 20 Ma to the present day. The third major kind of regional tectonic overprint is the Early Cretaceous me lange that is present as belts in and between the Rakaia and Pahau terranes. In part this me lange is probably coeval with the Haast Schist mineral growth, but it formed in the shallower parts

Estimates of the timing of the end of Palaeozoic Mesozoic subduction range from 125 Ma to 85 Ma. The youngest clearly subduction-related plutonic suites are 125 Ma old, and the oldest rift-related alkaline volcanics are about 100 Ma old. Detrital zircon dates of about 100 Ma have been obtained from sandstones imbricated in the accretionary wedge of the Pahau Terrane, but ignimbrites that fill extensional half-grabens are 105100 Ma old. The two metamorphic core complexes, Paparoa and Fiordland, also attest to extreme local continental extension at around 105 Ma. Hypotheses about the reason for the cessation of subduction in the Cretaceous include migration of a spreading ridge along the trench, stalling of spreading outboard of the trench, and collision of the Hikurangi Plateau large igneous province (Figure 1) with the Gondwanan margin. Late Early Cretaceous sedimentary rocks typically comprise synrift non-marine deposits succeeded by passive-margin marine transgressive strata.Late CretaceousPalaeogene Passive Margin

The oldest oceanic crust adjacent to the Challenger and Campbell Plateaus is about 85 Ma old. Spreading in the Tasman Sea ceased at about 55 Ma. New Zealand moved north (Figure 3) due to continuing spreading on the PacificAntarctic Ridge. Marine basins developed across Zealandia as a result of post-rift thermal subsidence. The maximum marine inundation of Zealandia, with widespread limestone deposition, occurred in the Oligocene, but local fluvial and coal deposits dating from throughout the

NEW ZEALAND 7

Late CretaceousCenozoic (albeit in different parts of North and South islands) indicate that Zealandia was never entirely submerged.MiocenePliocene Active Margin Development

The entire basement and its cover of passive-margin Late Cretaceous to Palaeogene sediments were subjected to renewed deformation in the Neogene with the inception of the modern AustraliaPacific plate margin.

By earliest Miocene times, a new plate boundary (in broadly the same place as the present-day boundary; Figure 1) had propagated through Zealandia and cut across the trend of the basement terranes. The development of the PacificAustralian plate boundary had profound geological consequences. The Northland and East Coast allochthons, consisting of Late CretaceousPalaeogene ophiolitic and sedimentary rocks, were thrust onto North Island from the north-east at the end of the Oligocene (ca. 25 Ma). Subductionrelated arc volcanism started at about 25 Ma and became widespread in Northland and the Coromandel between 15 Ma and 5 Ma. On South Island, intraplate stratovolcanoes developed along the east coast. The Neogene succession is generally thick, clastic-dominated, and regressive.Quaternary

See AlsoAntarctic. Australia: Tasman Orogenic Belt. Gondwanaland and Gondwana. Large Igneous Provinces. Oceania (Including Fiji, PNG and Solomons). Plate Tectonics. Tectonics: Convergent Plate Boundaries and Accretionary Wedges.

Further ReadingAdams CJ, Campbell HJ, Graham IJ, and Mortimer N (1998) Torlesse, Waipapa and Caples suspect terranes of New Zealand: Integrated studies of their geological his tory in relation to neighbouring terranes. Episodes 21: 235 240. Ballance PF (ed.) (1993) South Pacific Sedimentary Basins. Sedimentary Basins of the World 2. Amsterdam: Elsevier. Bradshaw JD (1989) Cretaceous geotectonic patterns in the New Zealand region. Tectonics 8: 803 820. Cole JW (1986) Distribution and tectonic setting of Late Cenozoic volcanism in New Zealand. Bulletin of the Royal Society of New Zealand 23: 7 20. King PR (2000) Tectonic reconstructions of New Zealand: 40 Ma to the present. New Zealand Journal of Geology and Geophysics 43: 611 638. Korsch RJ and Wellman HW (1988) The geological evolu tion of New Zealand and the New Zealand region. In: Nairn AEM, Stehli FG, and Uyeda S (eds.) The Ocean Basins and Their Margins, vol. 7B, pp. 411 482. New York: Plenum Press. Lee DE, Lee WG, and Mortimer N (2001) Where and why have all the flowers gone? Depletion and turnover in the New Zealand Cenozoic angiosperm flora in relation to palaeogeography and climate. Australian Journal of Botany 49: 341 356. Mortimer N (2004) New Zealands geological foundations. Gondwana Research 7: 261 272. Sutherland R (1999) Basement geology and tectonic devel opment of the greater New Zealand region: an interpret ation from regional magnetic data. Tectonophysics 308: 341 362.

Although they are part of the continuing Neogene volcanotectonic phase, Quaternary rocks are shown separately in Figure 2 because of their wide areal extent and strong association with present-day landforms. The subduction-related Quaternary volcanoes of North Island have erupted extensive ignimbrite sheets, which blanket the older rocks. In South Island large fluvioglacial outwash plains issue from glacially eroded valleys.

ConclusionsThe Phanerozoic geological history of New Zealand can be interpreted in terms of the progressive Pacificwards growth of Gondwana by terrane accretion and batholith intrusion at an obliquely convergent margin. Continental growth was terminated by widespread extension in southern Gondwana from about 105 Ma and was followed by seafloor spreading from about 85 Ma in the Tasman Sea and Southern Ocean.

8 NORTH AMERICA/Precambrian Continental Nucleus

NORTH AMERICAContents Precambrian Continental Nucleus Continental Interior Northern Cordillera Southern Cordillera Ouachitas Southern and Central Appalachians Northern Appalachians Atlantic Margin This event liberated the large North American fragment (Laurentia) out of the parental landmass of Rodinia. Since this breakup, the west coast of Laurentia (present coordinates) has been a long-lived active margin facing oceanic plates and colliding island arcs, whereas its eastern margin was modified by yet another major collision and rifting cycle, first forming the Appalachian-Caledonian Mountain (see North America: Southern and Central Appalachians) Belt, and finally rifting, starting at ca. 200 Ma, to form the present-day Atlantic Ocean basin. (see North America: Atlantic Margin) These events have modified the margins of Laurentia and added marginal terranes of mostly younger crust, such as the Coast Mountains of British Columbia, large parts of Alaska (see North America: Northern Cordillera), and Gondwana-derived terranes along the eastern seaboard. Nevertheless, North America remains dominated by Precambrian crust, with a mean isotopic age >2 Ga. The ancient crustal core of the continent, parts of which are exposed in the Canadian Shield (Figure 2), is underlain by subcontinental mantle lithosphere of above average thickness, which locally reaches down to a depth of 200300 km into the hotter, convective mantle. This mantle keel developed during or shortly after the amalgamation events in the crust, either by thermal growth (i.e., cooling from the top downwards) or by lateral accretion of buoyant slabs of depleted peridotite. The lithospheric keel is currently a reservoir of diamonds, a high-pressure polymorph of carbon. Transported to the surface by exotic volcanic rocks known as kimberlites, these valuable gemstones are now being produced from several mines across northern Canada (Figure 3). The mantle keel is mechanically coupled with the overlying crust, forming a thick and somewhat cooler lithosphere that enhances the strength and

Precambrian Continental NucleusW Bleeker, Geological Survey of Canada, Ottawa, ON, Canada 2005, Elsevier Ltd. All Rights Reserved.

IntroductionNorth America is a large continent and much of it is ancient (Figure 1). Fringed along several of its coastlines by younger mountain ranges, the broad interior of the continent is underlain by crust that ranges in age from >4.0 Ga to 2.5 Ga) crust, the Archaean cratons (see Precambrian: Overview). Among these, the Superior, Wyoming, and Slave cratons are some of the better-known examples. These crustal fragments are called cratons because they show long-term stability, having been affected by younger deformation only around their edges. The typical length scale of these Archaean cratons is ca. 1000 km. The Superior Craton is the largest preserved Archaean craton on Earth. . Furthermore, the larger Archaean cratons are typically composite, consisting of a number of domains with disparate crust formation ages. Included among these domains are ancient crustal fragments that are dominated by gneissic granitoids with ages of crystallization or inheritance of >2.93.0 Ga. Such ancient gneiss domains (e.g., the Central Slave Basement Complex of the Slave Craton; or the North Caribou Terrane of the Superior Craton; see Figure 4) have typical length scales of 100300 km. . Finally, these ancient gneiss domains are themselves heterogeneous. Embedded within them are found Earths oldest rocks, including, for instance, the 4.03 Ga Acasta gneisses of the Slave Craton (Figures 2A and 4). Individual examples of these

Precambrian Nucleus of North America: General StructureThe basic architecture of the Precambrian nucleus of North America is that of a collage comprising crustal elements of different ages (Figure 1). Many

NORTH AMERICA/Precambrian Continental Nucleus 13

Figure 4 (A) Cartoon illustrating the systematic fractal architecture of the Precambrian crust. The Precambrian record consists of a collage of nested fragments across a variety of scales. At the largest scale, Laurentia itself represents a rifted fragment of Rodinia, a ca 1 Ga supercontinent. Its margins formed between 780 600 Ma, when Rodinia started to break up. At the smallest scale, we find individual gneiss complexes consisting of some the oldest intact rocks on Earth (e.g., Acasta, Isua), nested within larger Archaean cratons. The overall fractal structure is one of preservation and reflects repeated cycles of fragmentation and re aggregation, with smaller older fragments preserved in larger younger fragments. Abbreviations: CSBC, Central Slave Basement Complex, Slave Craton; NCT, North Caribou Terrane, Superior Craton; MRVT, Minnesota River Valley Terrane. (B) An identical fractal pattern of nested fragments, but at smaller scales, is seen in this picture of the icy crust of Europa, one of Jupiters large moons (source: NASA, Galileo Orbiter PIA01127). Linear features are ridges formed by upwelling and subsequent freezing of water along cracks.

Early Archaean gneiss complexes are typically preserved at the 110 km scale, in some cases ranging up to ca. 100 km. Hence, the structure of the Precambrian nucleus of North America, and that of the geological record in general, is self-similar (fractal) in nature, repeating a basic motif across a variety of scales, ranging from the size of modern plates to that of individual ancient gneiss complexes or the greenstones belts embedded within them. As plate tectonics is the dominant process in shaping this pattern on the modern

Earth, it is tempting to conclude that plate tectonics must have been equally dominant since at least ca. 4.0 Ga, the time of the Earths oldest preserved crust (Figure 6). One might also conclude that plates have grown in size over time. These conclusions seem reasonable but there are a number of important caveats. The similarity in basic pattern strongly suggests repeated fragmentation and dispersal events of preexisting crust, with fragments becoming incorporated in new crustal collages through time. However, similarity in pattern and implied kinematic processes

14 NORTH AMERICA/Precambrian Continental Nucleus

Figure 5 The history of crustal aggregation states (supercratons, supercontinents) through time (vertical axis; modified after Bleeker, 2003). Mid Proterozoic Nuna, including the large 1.8 Ga core of Laurentia, was probably the first true supercontinent in Earth history. The Late Archaean may have been characterized by several discrete, transient, aggregations referred to as super cratons: Vaalbara, Superia, Sclavia and possibly others. The diachronous break up of these supercratons, in the Palaeoproterozoic, spawned the present ensemble of ca. 35 Archaean cratons, which now are variably incorporated into younger crustal collages. Since the assembly of Nuna, the time gaps between successive crustal aggregation maxima appear to have become shorter. Note the correlation of intervals of global glaciation with two periods of continental breakup and dispersal, and with possible minima in the frequency of mafic magmatic events in the continental record (legend for the latter: red line, well established mantle plume event; black line, other mafic magmatic event; dashed line, poorly dated event; modified after Ernst and Buchan (2001).

does not necessitate similarity at a dynamic process level. Modern lithospheric plates tend to be large and relatively rigid, and negative buoyancy of subducting, old and cold oceanic plates (slab pull) is a major component in the overall force balance driving plate motions. At present, it is controversial whether in a hotter Archaean Earth, with 24 times the present heat production and a more substantial fraction of the primordial heat budget still preserved inside the Earth, thinner and smaller lithospheric plates interacted the same way as their modern counterparts. A key question is whether the return flow of oceanic mafic-ultramafic material was by rigid slab

subduction (i.e., plate tectonics) or whether residues, after tonalitic melt extraction, descended back into the convecting mantle by more disorganized gravitational sinking (drip tectonics)? Attempts to answer this question from the geological record, as preserved in Archaean cratons, leaves little doubt that the cratons preserve a record of interaction between different crustal fragments. Nevertheless, Archaean cratons lack a fully diagnostic set of criteria confirming modern plate behaviour (e.g., passive margins, flexural basins, accretionary prisms, uncontested ophiolites, high pressure-low temperature metamorphic rocks and

NORTH AMERICA/Precambrian Continental Nucleus 15

of the major continental plates today. The Superior Craton of North America, the largest extant Archaean Craton, with a surface area of ca. 1.57 106 km2, is about half the size of the Arabian Plate. Indeed, several independent lines of evidence suggest that Archaean continental aggregations may have been smaller and more transient than their modern counterparts: . A hotter Archaean Earth, with a substantially higher radiogenic element budget, favours smaller and faster plates to dissipate the increased heat production and avoid catastrophic heating of the planetary interior. . The record of 87Sr/86Sr isotopic compositions of Precambrian seawater, as measured from marine carbonates, shows that prior to 2.62.5 Ga, Sr ratios were buffered by dominant interaction with oceanic crust and young mantle-derived mafic rocks. Only after ca. 2.5 Ga do we see a rapid rise in the 87Sr/86Sr ratios, reflecting more significant input from weathering of aged continental crust. . Much of the modern detrital sediment load to sedimentary basins and continental shelf-slope systems is provided by large river systems draining large continental hinterlands. The fact that there are few examples of large sedimentary basins of a shelfslope affinity preserved in the Archaean record, suggests that river systems and their continental hinterlands were smaller, and that large, emerged continental plates were rare or absent. . As attested by Laurentia, once large cratonic landmasses have aggregated and become underlain by a lithospheric keel, they tend to resist breakup. So, as noted above, the observation that none of the Archaean fragments, with their lithospheric keels, approaches modern continents in size may be significant after all. . Characteristics of the supercontinent cycle (Figure 5) suggest that the successive time lags between breakup and dispersal of one supercontinent (e.g., Rodinia) and the re-aggregation of a subsequent supercontinent (e.g., Pangaea) have become shorter over the last 2.5 billion years. The easiest explanation for this observation is that, following supercontinent breakup and dispersal, modern continental plates, due to their large average size, quickly run out of room and start colliding. More substantial time lags in the past suggest smaller continental plates. . And finally, Earths present rate of heat loss is about twice the rate of internal heat production, while at the same time heat production (mainly from K, Th, U) is undergoing slow exponential decay. Thermal arguments predict therefore that,

Figure 6 Backscatter electron image of a ca. 4.0 Ga zircon crystal from the Acasta gneisses, Earths oldest intact rocks (see also Figure 2A). Metamorphic rims formed at ca. 3.6 Ga. Oval spots are scars from the ion probe beam (from Stern and Bleeker, 1998).

paired metamorphic belts, etc.). Hence, it is useful to consider alternative explanations. In doing so, it is also instructive to consider other planetary bodies and their unique pathways of lithospheric evolution. For a comparison with the fractal pattern of repeated fragmentation and amalgamation in the Earths crust, the icy crust of Europa, one of Jupiters large moons (Figure 4B), is of particular interest (see Solar System: Jupiter, Saturn and Their Moons). Europas crust of water-ice, overlying an interior ocean, shows a fractal pattern that is essentially similar to that of Earths crust, requiring repeated fragmentation events, upwelling and freezing of water along cracks, and lateral mobility of fragments. Yet it is not the product of plate tectonics driven by rigid slab subduction of dense silicate rocks. Both on Europa and Earth, the fractal pattern of smaller, older fragments embedded in younger crustal collages, is an artefact of the process by which fragments are created and preserved. With each repeated breakup event, crustal fragments can only become smaller, while their number will increase. On the other hand, erosion, tectonic slivering, and partial subduction will, over time, reduce the number of fragments or hide them in the lower crust. Furthermore, a fragment of a certain size and age can only be preserved in a younger fragment that is either the same size or larger. Hence, the negative correlation between fragment size and age, as illustrated in Figure 4, is primarily a function of how continental crust is preserved, and may not provide information on whether continental plates have grown in average size over geological time. Nevertheless, it is intriguing that few of the Archaean cratons come close in size to even the smallest

16 NORTH AMERICA/Precambrian Continental Nucleus

over time, the lithosphere will slowly thicken and stiffen, evolving ultimately to a relatively immobile one-plate state. This state has already been reached by our closest sister planet, Venus, which is only marginally smaller than Earth (Venus radius is 95% that of Earth).

Precambrian Nucleus of North America: A Systematic OverviewFrom 2.0 Ga to 1.8 Ga, over a time-span of about 200 million years, the core of Laurentia formed by progressive amalgamation of 67 large fragments of Archaean crust and intervening island arcs into a broad orogenic collage (Figure 1). Crustal shortening and thickening accompanying the various accretion and collision events led to uplift and exhumation and, ultimately, stabilization of the newly formed crust, as indicated by the initiation of widespread intracontinental sedimentary basins that overstep the boundaries between different crustal blocks as early as ca 1.75 Ga. Interestingly, the time-frame of relatively rapid crustal aggregation and growth implied for Laurentia is of a similar order to that for the progressive development of the most recent supercontinent, Pangaea, which started with assembly of the large southern continent Gondwana in the latest Proterozoic and terminated with final collision of Gondwana and Laurasia in the Carboniferous to Permian (i.e., an overall time-frame of ca. 250 Ma). The widespread 2.01.8 Ga orogenic events in Laurentia, known in North America as the Hudsonian Orogeny, have counterparts in most other continents (e.g., the Amazonian Orogeny in Brazil; the Svecofennian Orogeny of the Baltic Shield; the Capricorn Orogeny of Western Australia). Through the collective amalgamation of a large number of disparate Archaean cratons or microcontinents into a global collage, this first-order orogenic event may have led to the first true supercontinent in Earth history at about 1.75 Ga named Nuna (Figure 5). Through further crustal growth along its external margins, and final continentcontinent collision to form the Grenville Orogen along its southeastern margin (Figure 1), Nuna evolved into ca. 1 Ga Rodinia. Clearly, the Archaean cratons are the dominant building blocks in the Palaeoproterozoic assembly of Laurentia, and the core of Nuna. Hence, they form a logical starting point for a brief systematic overview of the Precambrian crust.The Archaean Cratons

cratons; the highly reworked Rae and Hearne cratons, collectively known as the Churchill structural province; the enigmatic Sask Craton, which underlies much of the Palaeoproterozoic Trans-Hudson Orogen in central Canada; and the Nain or North Atlantic Craton underlying southern Greenland (Figure 1). These cratons represent a subset out of a total ensemble of about 35 large Archaean crustal fragments preserved around the world. The independent nature of some of the component cratons of Laurentia is still a matter of debate. Clearly, the well-studied Superior and Slave cratons are two pieces of crust that are exotic relative to each other and most likely originated from unrelated ancestral landmasses the Late Archaean supercratons Superia and Sclavia, respectively (Figure 5). The ancestry of some of the other cratons is less clear. A putative suture between the Hearne and Rae cratons, the Snowbird Tectonic Zone (Figure 1), remains controversial. Hence, it is possible that the Hearne and Rae cratons represent a contiguous fragment of Archaean crust. The Hearne Craton is locally overlain by an Early Proterozoic cover sequence, the ca. 2.42.1 Ga Hurwitz Group, which shows similarities to the Huronian Supergroup overlying the southern Superior Craton. Both sequences contain evidence for ca. 2.3 Ga low-latitude glaciations. Futhermore, both cratons are cross-cut by ca. 2450 Ma mafic dykes. Palaeomagnetic data from these dykes suggest that the Hearne Craton may have originated, at 2450 Ma, from just south of the Huronian margin of the Superior Craton (Figure 7). Thus, both cratons likely originated from within supercraton Superia, possibly along with others such as the Karelia, Nain and Yilgarn cratons. Whether the Wyoming Craton, underlying much of the north-western United States, is truly distinct or just a southern continuation of the Hearne Craton also remains unclear. The proposed suture between the Hearne and Wyoming cratons is buried underneath thick platform strata. The Sask Craton may be an exotic piece of crust or, alternatively, a partially detached piece of either the neighbouring Hearne or Superior Craton, incorporated in the Trans-Hudson Orogen. Interestingly, many of these fundamental questions can be resolved, in principle, with detailed palaeomagnetic studies and high-precision age dating of the Palaeoproterozoic mafic dyke swarms that cut the cratons, in conjunction with stratigraphic comparisons of the Archaean cratons and the Palaeoproterozoic cover sequences that overlie them.The Slave Craton

Individual Archaean cratons that constitute the core of Laurentia are: the Superior, Slave, and Wyoming

As an example of the Archaean components of Laurentia, the Slave Craton is described in more detail.

NORTH AMERICA/Precambrian Continental Nucleus 17

Figure 7 Possible reconstruction of the relative position of the Superior and Hearne crustal fragments at ca. 2450 Ma, prior to the inferred break up of their ancestral supercraton, Superia. Both cratons are cut by ca. 2450 Ma mafic dykes that are petrographi cally similar, the Kaminak dykes (K) of the northern Hearne and the Matachewan dykes (M) of the southern Superior, respect ively. Palaeomagnetic data from both dyke swarms allow the reconstruction shown here. Both dyke swarms and the inferred break up of Superia may have been consequences of the ca 2450 Ma Matachewan plume (black star). Karelia, another Ar chaean craton now embedded in the Baltic Shield, also hosts ca 2450 Ma mafic dykes and, thus, may have been part of Superia. Also shown is a possible topology of intracontinental rift zones along which supercraton Superia broke up, liberating individual cratons. Plumes or hotspots along this rift zone (open stars) may have had ages spreading out over a 100 200 million year interval, similar to those along the mid Atlantic rift during progressive break up of Pangaea.

(Figure 2D) and high-amplitude basement-cored domes. The overall result is an archetypical Archaean granite-greenstone terrane. The younger granites are part of a craton-wide, ca. 2.592.58 Ga granite bloom, which transported heat, partial melt fractions, and aqueous fluids, as well as most of the incompatible heat producing elements (K, U, Th), from the hot lower crust to the upper crust. This critical and irreversible step allowed the lower crust to cool and to mechanically couple with the mantle lithosphere. Shortly following this terminal granite bloom, Slave crust stabilized and became cratonic. Following cratonization, from 2.58 Ga to 2.2 2.0 Ga, Slave crust was gradually exhumed by ca. 1015 km (on average) through slow uplif