Tài liệu Quaternary dating methods

Quaternary Dating Methods MIKE WALKER Department of Archaeology and Anthropology University of Wales, Lampeter, UK Quaternary Dating Methods Quaternary Dating Methods MIKE WALKER Department of Archaeology and Anthropology University of Wales, Lampeter, UK Copyright © 2005 John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England Telephone (+44) 1243 779777 Email (for orders and customer service enquiries): [email protected] Visit our Home Page on www.wiley.com All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except under the terms of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London W1T 4LP, UK, without the permission in writing of the Publisher. 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For John Lowe Contents Preface xv 1 Dating Methods and the Quaternary 1.1 Introduction 1.2 The Development of Quaternary Dating 1.3 Precision and Accuracy in Dating 1.4 Atomic Structure, Radioactivity and Radiometric Dating 1.5 The Quaternary: Stratigraphic Framework and Terminology 1.6 The Scope and Content of the Book Notes 1 1 2 5 7 9 12 15 2 Radiometric Dating 1: Radiocarbon Dating 2.1 Introduction 2.2 Basic Principles 2.3 Radiocarbon Measurement 2.3.1 Beta Counting 2.3.2 Accelerator Mass Spectrometry 2.3.3 Extending the Radiocarbon Timescale 2.3.4 Laboratory Intercomparisons 2.4 Sources of Error in Radiocarbon Dating 2.4.1 Contamination 2.4.2 Isotopic Fractionation 2.4.3 Marine Reservoir Effects 2.4.4 Long-Term Variations in 14C Production 2.5 Some Problematic Dating Materials 2.5.1 Lake Sediments 2.5.2 Shell 2.5.3 Bone 2.5.4 Soil 2.6 Calibration of the Radiocarbon Timescale 2.6.1 Dendrochronological Calibration 2.6.2 The INTCAL Calibration 2.6.3 Extending the Radiocarbon Calibration Curve 17 17 18 19 20 20 23 24 24 24 25 26 27 29 29 30 31 31 32 32 32 34 viii Contents 2.6.4 Bayesian Analysis and Radiocarbon Calibration 2.6.5 Wiggle-Match Dating 2.7 Applications of Radiocarbon Dating 2.7.1 Radiocarbon Dating: Some Routine Applications 2.7.1.1 Dating of plant macrofossils: Lateglacial cereal cultivation in the valley of the Euphrates 2.7.1.2 Dating of charcoal: a Holocene palaeoenvironmental record from western Germany 2.7.1.3 Dating of peat: a Holocene palaeoclimatic record from northern England 2.7.1.4 Dating of organic lake mud: a multi-proxy palaeoenvironmental record from Lake Rutundu, East Africa 2.7.1.5 Dating of marine micropalaeontological records: an example of a problem from the North Atlantic 2.7.1.6 Dating of marine shell: a Holocene aeolianite from Mexico 2.7.1.7 Dating of bone: the earliest humans in the Americas 2.7.2 Radiocarbon Dating of Other Materials 2.7.2.1 Dating of textiles: the ‘Shroud of Turin’ 2.7.2.2 Dating of old documents: the Vinland Map 2.7.2.3 Dating of lime mortar: medieval churches in Finland 2.7.2.4 Dating of hair: radiocarbon dates and DNA from individual animal hairs 2.7.2.5 Dating of iron artefacts: the Himeji nail and the Damascus sword 2.7.2.6 Dating of pottery: the earliest pottery in Japan 2.7.2.7 Dating of rock art: Palaeolithic cave paintings in Spain and France Notes 3 Radiometric Dating 2: Dating Using Long-Lived and Short-Lived Radioactive Isotopes 3.1 Introduction 3.2 Argon-Isotope Dating 3.2.1 Principles of Potassium–Argon Dating 3.2.2 Principles of Argon–Argon Dating 3.2.3 Some Assumptions and Problems Associated with Potassium–Argon and Argon–Argon Dating 3.2.4 Some Applications of Potassium–Argon and Argon–Argon Dating 3.2.4.1 Potassium–argon and argon–argon dating of the dispersal of Early Pleistocene hominids 3.2.4.2 40Ar/39Ar dating of anatomically modern Homo sapiens from Ethiopia 35 37 37 37 38 38 41 41 43 45 47 47 48 49 51 51 52 52 53 54 57 57 58 58 59 59 61 62 62 Contents Ar/39Ar dating of historical materials: the eruption of Vesuvius in AD 79 3.2.4.4 40Ar/39Ar dating and geological provenancing of a stone axe from Stonehenge, England 3.3 Uranium-Series Dating 3.3.1 Principles of U-Series Dating 3.3.2 Some Problems Associated with U-Series Dating 3.3.3 Some Applications of U-Series Dating 3.3.3.1 Dating the Last Interglacial high sea-level stand in Hawaii 3.3.3.2 Dating of early hominid remains from China 3.3.3.3 Dating of a speleothem from northern Norway 3.3.3.4 Dating of fluvial terraces in Wyoming, USA 3.4 Cosmogenic Nuclide Dating 3.4.1 Principles of Cosmogenic Nuclide (CN) Dating 3.4.2 Sources of Error in CN Dating 3.4.3 Some Applications of CN Dating 3.4.3.1 Cosmogenic dating of two Late Pleistocene glacial advances in Alaska 3.4.3.2 Cosmogenic dating of the Salpausselkä I formation in Finland 3.4.3.3 Cosmogenic dating of Holocene landsliding, The Storr, Isle of Skye, Scotland 3.4.3.4 Cosmogenic dating of alluvial deposits, Ajo Mountains, southern Arizona, USA 3.5 Dating Using Short-Lived Isotopes 3.5.1 Lead-210 (210Pb) 3.5.2 Caesium-137 (137Cs) 3.5.3 Silicon-32 (32Si) 3.5.4 Some Problems in Using Short-Lived Isotopes 3.5.5 Some Dating Applications Using Short-Lived Isotopes 3.5.5.1 Dating a record of human impact in a lake sequence in northern England 3.5.5.2 Dating a 500-year lake sediment/temperature record from Baffin Island, Canada 3.5.5.3 32Si dating of marine sediments from Bangladesh Notes 3.2.4.3 ix 40 4 Radiometric Dating 3: Radiation Exposure Dating 4.1 Introduction 4.2 Luminescence Dating 4.2.1 Thermoluminescence (TL) 4.2.2 Optically Stimulated Luminescence (OSL) 4.2.3 Sources of Error in Luminescence Dating 4.2.4 Some Applications of Luminescence Dating 65 66 66 67 69 71 71 72 74 74 77 77 79 80 80 82 82 84 84 85 86 86 87 87 88 88 91 92 93 93 94 94 96 99 100 x Contents 4.2.4.1 TL dating of Early Iron Age iron smelting in Ghana 4.2.4.2 TL and AMS radiocarbon dating of pottery from the Russian Far East 4.2.4.3 TL dating of burnt flint from a cave site in France 4.2.4.4 TL dating of the first humans in South America 4.2.4.5 OSL dating of young coastal dunes in the northern Netherlands 4.2.4.6 OSL dating of dune sands from Blombos Cave, South Africa: single and multiple grain data 4.2.4.7 OSL dating of fluvial deposits in the lower Mississippi Valley, USA 4.2.4.8 OSL dating of marine deposits in Denmark 4.3 Electron Spin Resonance Dating 4.3.1 Principles of ESR Dating 4.3.2 Sources of Error in ESR Dating 4.3.3 Some Applications of ESR Dating 4.3.3.1 ESR dating of teeth from the Hoxnian Interglacial type locality, England 4.3.3.2 ESR dating of mollusc shells from the Northern Caucasus and the earliest humans in eastern Europe 4.3.3.3 ESR dating of Holocene coral: an experimental approach 4.3.3.4 ESR dating of quartz: the Toba super-eruption 4.4 Fission Track Dating 4.4.1 Principles of Fission Track Dating 4.4.2 Some Problems Associated with Fission Track Dating 4.4.3 Some Applications of Fission Track Dating 4.4.3.1 Fission track dating of glacial events in Argentina 4.4.3.2 Fission track dating of a Middle Pleistocene fossiliferous sequence from central Italy 4.4.3.3 Dating of obsidian in the Andes, South America, and the sourcing of artefacts Notes 5 Dating Using Annually Banded Records 5.1 Introduction 5.2 Dendrochronology 5.2.1 Principles of Dendrochronology 5.2.2 Problems Associated with Dendrochronology 5.2.3 Dendrochronological Series 5.2.4 Applications of Dendrochronology 5.2.4.1 Dating a 2000-year temperature record for the northern hemisphere 5.2.4.2 Dating historical precipitation records 100 101 102 103 104 104 107 108 109 109 110 110 111 112 113 113 114 115 116 116 116 117 117 119 121 121 122 122 123 125 127 128 128 Contents 5.3 5.4 5.5 5.6 5.2.4.3 Dating volcanic events 5.2.4.4 Dating archaeological evidence Varve Chronology 5.3.1 The Nature of Varved Sediments 5.3.2 Sources of Error in Varve Chronologies 5.3.3 Applications of Varve Chronologies 5.3.3.1 Dating regional patterns of deglaciation in Scandinavia 5.3.3.2 Dating prehistoric land-use changes 5.3.3.3 Dating long-term climatic and environmental changes 5.3.3.4 Varve sequences and the radiocarbon timescale Lichenometry 5.4.1 Principles of Lichenometric Dating 5.4.2 Problems Associated with Lichenometric Dating 5.4.3 Lichenometry and Late Holocene Environments 5.4.3.1 Dating post-Little Ice Age glacier recession in Norway 5.4.3.2 Dating rock glaciers and Little Ice Age moraines in the Sierra Nevada, western USA 5.4.3.3 Dating Late Holocene rockfall activity on a Norwegian talus slope 5.4.3.4 Dating archaeological features on raised shorelines in northern Sweden Annual Layers in Glacier Ice 5.5.1 Ice-Core Chronologies 5.5.2 Errors in Ice-Core Chronologies 5.5.3 Ice Cores and the Quaternary Palaeoenvironmental Record 5.5.3.1 Dating climatic instability as revealed in the Greenland ice cores 5.5.3.2 Dating rapid climate change: the end of the Younger Dryas in Greenland 5.5.3.3 Dating long-term variations in atmospheric Greenhouse Trace Gases 5.5.3.4 Dating human impact on climate as reflected in ice-core records Other Media Dated by Annual Banding 5.6.1 Speleothems 5.6.1.1 Dating a proxy record for twentieth-century precipitation from Poole’s Cavern, England 5.6.1.2 Dating climate variability in central China over the last 1270 years 5.6.2 Corals 5.6.2.1 Dating a 420-year-coral-based palaeoenvironmental record from the southwestern Pacific 5.6.2.2 Dating a 240-year palaeoprecipitation record from Florida, USA xi 129 130 132 133 135 136 136 136 139 140 141 142 142 143 144 144 146 147 148 149 150 151 151 152 154 155 156 156 156 157 158 158 158 xii Contents 5.6.3 Molluscs 5.6.3.1 The development of a sclerochronology using the long-lived bivalve Arctica islandica 5.6.3.2 The development of a ‘clam-ring’ master chronology from a short-lived bivalve mollusc and its palaeoenvironmental significance Notes 6 Relative Dating Methods 6.1 Introduction 6.2 Rock Surface Weathering 6.2.1 Surface Weathering Features 6.2.2 Problems in Using Surface Weathering Features to Establish Relative Chronologies 6.2.3 Applications of Surface Weathering Dating 6.2.3.1 Relative dating of Holocene glacier fluctuations in the Nepal Himalaya 6.2.3.2 Relative dating of periglacial trimlines in northwest Scotland 6.2.3.3 Relative dating of archaeological features by Lake Superior, Canada 6.3 Obsidian Hydration Dating 6.3.1 The Hydration Layer 6.3.2 Problems with Obsidian Hydration Dating 6.3.3 Some Applications of Obsidian Hydration Dating 6.3.3.1 Dating of a Pleistocene age site, Manus Island, Papua New Guinea 6.3.3.2 Dating of fluvially reworked sediment in Montana, USA 6.4 Pedogenesis 6.4.1 Soil Development Indices 6.4.2 Problems in Using Pedogenesis as a Basis for Dating 6.4.3 Some Applications of Dating Based on Pedogenesis 6.4.3.1 Relative dating of moraines in the Sierra Nevada, California 6.4.3.2 Dating glacial events in southeastern Peru 6.5 Relative Dating of Fossil Bone 6.5.1 Post-Burial Changes in Fossil Bone 6.5.2 Problems in the Relative Dating of Bone 6.5.3 Some Applications of the Relative Dating of Bone 6.5.3.1 Fluoride dating of mastodon bone from an early palaeoindian site, eastern USA 6.5.3.2 Chemical dating of animal bones from Sweden 6.6 Amino Acid Geochronology 6.6.1 Proteins and Amino Acids 6.6.2 Amino Acid Diagenesis 6.6.3 Problems with Amino Acid Geochronology 160 160 162 162 165 165 166 166 167 168 168 168 170 172 173 173 174 174 176 176 176 177 178 178 178 180 181 181 182 182 182 184 185 186 187 Contents 6.6.4 Applications of Amino Acid Geochronology 6.6.4.1 Dating and correlation of the last interglacial shoreline (~MOI substage 5e) in Australia using aminostratigraphy 6.6.4.2 Quaternary aminostratigraphy in northwestern France based on non-marine molluscs 6.6.4.3 Dating the earliest modern humans in southern Africa using amino acid ratios in ostrich eggshell 6.6.4.4 Dating sea-level change in the Bahamas over the last half million years Notes 7 Techniques for Establishing Age Equivalence 7.1 Introduction 7.2 Oxygen Isotope Chronostratigraphy 7.2.1 Marine Oxygen Isotope Stages 7.2.2 Dating the Marine Oxygen Isotope Record 7.2.3 Problems with the Marine Oxygen Isotope Record 7.3 Tephrochronology 7.3.1 Tephras in Quaternary Sediments 7.3.2 Dating of Tephra Horizons 7.3.3 Problems with Tephrochronology 7.3.4 Applications of Tephrochronology 7.3.4.1 Dating the first human impact in New Zealand using tephrochronology 7.3.4.2 Dating and correlating events in the North Atlantic region during the Last Glacial–Interglacial transition using tephrochronology 7.3.4.3 Dating Middle Pleistocene artefacts and cultural traditions in East Africa using tephrostratigraphy 7.3.4.4 Dating Early and Middle Pleistocene glaciations in Yukon by tephrochronology 7.4 Palaeomagnetism 7.4.1 The Earth’s Magnetic Field 7.4.2 The Palaeomagnetic Record in Rocks and Sediments 7.4.3 Magnetostratigraphy 7.4.3.1 Polarity changes and the palaeomagnetic timescale 7.4.3.2 Secular variations 7.4.3.3 Mineral magnetic potential 7.4.4 Some Problems with Palaeomagnetic Dating 7.4.5 Applications of Palaeomagnetic Dating 7.4.5.1 Dating lake sediments using palaeosecular variations 7.4.5.2 Palaeomagnetic correlations between Scandinavian Ice Sheet fluctuations and Greenland ice-core records xiii 188 189 189 191 192 195 197 197 198 199 199 201 202 202 204 205 207 207 209 209 211 213 214 215 216 216 216 219 220 221 221 222 xiv Contents 7.4.5.3 Palaeomagnetic dating of the earliest humans in Europe 7.4.5.4 Palaeomagnetic dating of the Sterkfontein hominid, South Africa 7.5 Palaeosols 7.5.1 The Nature of Palaeosols 7.5.2 Palaeosols as Soil-Stratigraphic Units 7.5.3 Some Problems with Using Palaeosols to Establish Age Equivalence 7.5.4 Applications of Palaeosols in the Establishment of Age Equivalence 7.5.4.1 Buried palaeosols on the Avonmouth Level, southwest England: stratigraphic markers in Holocene intertidal sediments 7.5.4.2 The Valley Farm and Barham Soils: key stratigraphic marker horizons in southeast England 7.5.4.3 Correlation between the Chinese loess–palaeosol sequence and the deep-ocean core record for the past 2.5 million years Notes 223 224 225 227 228 229 230 230 231 233 235 8 Dating the Future 8.1 Introduction 8.2 Radiometric Dating 8.3 Annually Banded Records 8.4 Age Equivalence 8.5 Biomolecular Dating Notes 237 237 237 240 242 243 244 References Index 245 279 Preface In a letter to Thomas Manning in 1810, Charles Lamb wrote: ‘Nothing puzzles me more than time and space; and yet nothing troubles me less, as I never think about them.’ All of us working in the field of Quaternary science would, I suspect, tend to agree with the first part of this statement but take issue over the second. I for one have always been fascinated by time and, in particular, by the way in which we are able to assign ages to events in the distant past. My family and friends have been amused and intrigued in equal measure by me talking, with apparent confidence and authority, about the earth being formed 4.5 billion years ago, or the present warm period within which we live lasting 11 500 yrs. ‘But how can you be so sure?’ is the usual question. One of my aims in writing this book is to show them that there are indeed ways in which we can date the past and, moreover, that we can do so with an ever-increasing sense of assurance. My principal purpose, however, is to describe the various dating techniques that are routinely employed in Quaternary science in a way that is comprehensible to both undergraduate students and interested lay-people alike. I have therefore tried to avoid using mathematical formulae, although in the first chapter I felt it necessary to cover some of the basics of chemistry in order to provide the groundwork for what comes later. I have also orientated the book towards the practical aspects of dating by basing it around specific examples. Hopefully, this approach will appeal to students and others with a non-scientific background but, at the same time, will not appear to those who are fortunate in possessing a stronger scientific pedigree to be ‘dumbing down’. Above all, however, my aim is to encourage readers (unlike Charles Lamb) to think a little more about the past and to recognise the importance of being able to frame the momentous events of recent earth and human history within a reasonably secure temporal framework. Throughout the book I have drawn on a previous volume that I wrote with John Lowe (Reconstructing Quaternary Environments, 1997, Addison-Wesley-Longman, London). I make no apologies for this because I know that book has been, and continues to be, widely used at undergraduate and postgraduate levels in both Britain and abroad. I hope that this new book on Quaternary Dating Methods will find an equally wide readership. John and I are about to embark on the third edition of Reconstructing Quaternary Environments (due 2006), and during the course of preparing that revision, I hope I will be able to reciprocate and that some of the material contained in the following pages will find its way into Lowe and Walker Mark III. The text also includes a large number of references. Some might find that this disrupts the flow of the narrative, but I felt that it xvi Preface was important not only to acknowledge the sources of material upon which I have drawn but, equally importantly, to point the reader in the direction of this work so that those who might be interested in taking matters further will be able to do so. It is customary in a Preface to express thanks to those who have assisted either directly or indirectly in the production of the book, and I do not intend to depart from that practice. Over the last 15 years or so, I have enjoyed the national and international collaboration, and friendship, of many colleagues, first through the North Atlantic Seaboard Programme of IGCP-253, and more recently through the INTIMATE (Integration of ice-core, marine and terrestrial records) Programme of INQUA (International Quaternary Union). I am particularly appreciative of the time that I have spent at a number of different meetings with, amongst others, Hilary Birks, Sjoerd Bohncke, Svante Björck, Russell Coope, Les Cwynar, Irka Hajdas, Jan Heinemeir, Wim Hoek, Konrad Hughen, Sigfus Johnsen, Karen-Luise Knudsen, Nalan Koç, Thomas Litt, Jørgen Peder Steffensen, Chris Turney, Bas van Geel and Barbara Wohlfarth. My work with the Natural Environmental Research Council, formerly as a member and subsequently as chairman of the NERC Radiocarbon Facilities Committee, and latterly as chairman of the NERC AMS (Accelerator Mass Spectrometry) Strategy Group, has brought me into contact with colleagues at the East Kilbride and Oxford Radiocarbon Dating Laboratories, notably Chris Bronk-Ramsay, Charlotte Bryant, Doug Harkness, Robert Hedges and Tony Fallick, whose company I have enjoyed and from whom I have learned a great deal. I should also like to thank Lin Kay and Chris Franklin at NERC for supporting me in my role as Committee Chairman. Finally, I am grateful to my colleagues in the Department of Archaeology and Anthropology, University of Wales, Lampeter, especially David Austin and John Crowther, for providing such a congenial working environment over the past four years, and to the university itself for allowing me a period of study leave during which much of the first draft of the book was completed. In writing this book, I have constantly been aware of the fact that I am approaching the material as a member of the user community. I am not an expert in the technical aspects of dating, and hence I have prevailed upon colleagues who know far more about these matters than I ever will to read what I have written and to show me where I have gone wrong. I am deeply indebted to Tim Atkinson, Simon Blockley, Charlotte Bryant, Tony Fallick, Rob Kemp, Olav Lian, Danny McCarroll, James Scourse, Mike Summerfield, Chris Turney and John Westgate for their careful scrutiny and constructive critical appraisal of various sections of the text; I simply could not have completed this book without their assistance. It goes without saying, however, that any remaining errors are my own. Several friends and colleagues have provided me with photographs, for which I am most grateful, and Phil Gibbard and Richard Preece helped considerably in the compilation of Figure 1.4. I should also like to thank Sally Wilkinson, Keily Larkins, Lynette James and the staff in the production department of John Wiley. Last, and by no means least, I would like to express my gratitude to my wife, Gro-Mette, who has not only been a constant source of encouragement, but who has also read the draft text from cover to cover, and has provided many valuable inputs along the way. One name is missing from the above list. As colleagues within the Quaternary community will know, for more than 30 years I have worked in collaboration with John Lowe. We first met as postgraduate students in the University of Edinburgh and since then we have produced more than 50 joint publications. I have no doubt whatsoever that Preface xvii John could have written this book and, I suspect, he might well have made a better fist of it. Nevertheless, I hope he will find some of the material in the following pages of interest and that he will enjoy reading it. Not only have John and I been close academic colleagues, but we have also remained firm friends, and in acknowledgement of this I would like to dedicate the book to him. Mike Walker October, 2004