The Chronology of the Geological Record The Chronology of the Geological Record
NO J. SNELLING British Geological Survey London
Memoir No 10 1985
Published for The Geological Society by Blackwell Scientific Publications Oxford London Edinburgh Boston Palo Alto Melbourne Published for The Geological Society by DISTRIBUTORS Blackwell Scientific Publications USA and Canada Editorial offices: Blackwell Scientific Publications Inc Osney Mead, Oxford, OX2 OEL P O Box 50009, Palo Alto, California 94303 8 John Street, London, WC1N 2ES 23 Ainslie Place, Edinburgh, EH3 6AJ Australia 52 Beacon Street, Boston, Massachusetts 02108, USA Blackwell Scientific Publications 667 Lytton Avenue, Palo Alto, California 94301, USA (Australia) Pty Ltd 101 Barry Street, Carlton, Victoria 3053, Australia 107 Barry Street, Carlton, Victoria 3053 (~ 1985 The Geological Society. Authorization to photocopy items for internal or personal use, or the internal or personal use of specific British Library Cataloguing in Publication Data clients, is granted by The Geological Society for libraries and other The Chronology of the geological record. users registered with the Copyright Clearance Center (CCC) Trans- 1. Geological time actional Reporting Service, provided that a base fee of $02.00 per I. Snelling, N.J. copy is paid directly to CCC, 21 Congress Street, Salem, MA 01970, 551.7'01 QE508 USA. 0305-8719/84 $02.00 ISBN 0-632-01285-4 First published 1985
Set by Setrite Ltd Hong Kong and printed in Great Britain by Hollen Street Press, Slough, Berks. Contents
Preface: SNELLING, N. J., vii ODIN, G. S. Concerning the numerical ages proposed for the Jurassic and Cretaceous geochronology, 196 JENKINS, D. J., BOWEN, D. Q., ADAMS, C. G., SHACKLETON, Part 1: Geochronology and the N. J. & BRASSELL, S. C. The Neogene: Part 1, 199. geological time-scale BERGGREN, W. A., KENT, D. V. & VAN COUVERING, J. A. The Neogene: Part 2. Neogene geochronology and SNELLING, N. J. Geochronology and chronostratigraphy, 211 the geological record, 3 SNELLING, N. J. An interim time-scale, 261 MOORBATH, S. • TAYLOR, P. N. Precambrian geochronology and the geological record, 10 WRIGHT, A. E. Subdivision of the Precambrian, 29 Part 2: The geological record ODIN, G. S. Some key rules for the calibration of the numerical time-scale, 41 CURRY, D. Oceanic magnetic lineaments and the calibration COWIE, J. W. & JOHNSON, M. R. W. Late Precambrian and of the late Mesozoic-Cenozoic time-scale, 269 Cambrian geological time-scale, 47 HOUSE, M. R. The ammonoid time-scale and the ammonoid ODIN, G. S., GALE, N. H. t~ DORI~, F. Radiometric dating of evolution, 273 Late Precambrian times, 65 GREGOR C. B. The mass-age distribution of Phanerozoic MCKERROW, W. S., LAMBERT, R. ST J. & COCKS, L. R. M. sediments, 284 The Ordovician, Silurian and Devonian periods, 73 CLAUER, N. & HOFFERT, M. Sr isotopic constraints for the GALE, N. H. Numerical calibration of the Palaeozoic time- sedimentation rate of deep sea red clays in the southern scale; Ordovician, Silurian and Devonian periods, 81 Pacific Ocean, 290 KUNK, M. J., SUTrER, J., OBRADOVICH,J. D. r RAYNOLDS, R. G. H. & JOHNSON, G. D. Rates of Neogene LANPrtERE, M. A. Age of biostratigraphic horizons within depositional and deformational processes, north-west the Ordovician and Silurian systems, 89 Himalayan foredeep margin, Pakistan, 297 ODIN, G. S. Remarks on the numerical scale of Ordovician to J~,GER, E. Geochronology in the Central Alps; dating of Devonian times, 93 metamorphism, subsequent cooling with Oligocene FORSTER, S. C. t~ WARRINGTON, G. Geochronology of the glaciation, and the development of the recent Carboniferous, Permian and Triassic, 99 landscape, 312 ODIN, G. S. Comments on the geochronology of the DODSON, M. H. & MCCLELLAND-BROWN, E. Isotopic and Carboniferous to Triassic times, 114 palaeomagnetic evidence for rates of cooling, uplift and HALLAM, A., HANCOCK,J. M., LA BREQUE, J. L., erosion, 315 LOWRIE, W. & CrtANNELL, J. E. T. Jurassic to Paleogene: BROWN, G. C. Processes and problems in the continental Part 1. Jurassic and Cretaceous geochronology and Jurassic lithosphere: geological history and physical to Paleogene magnetostratigraphy, 118 implications, 326 BERGGREN, W. A., KENT, D. V. & FLYNN, J. J. Jurassic to Paleogene: Part 2. Paleogene geochronology and chronostratigraphy, 141 Index, 335 Preface
The measurement of geological time and the construction of re-evaluated The Phanerozoic Time-Scale data bank a geologic time-scale composed of standard stratigraphic eliminating nearly half of the pre-Cenozoic data but replacing divisions based on rock sequences and calibrated in years has them by as much and more new data. The latter work also long attracted the attention of geologists and has done much reassesses the previous data and in addition incorporates a to pro.voke international co-operation. Thus the Committee new data bank of 251 items with very detailed comment on, for the Measurement of Geological Time, set up in and evaluation of, their radiometric and stratigraphic December 1923 by the National Research Council of the significance. USA almost immediately attracted the co-operation of the The contributors to this volume have among other things pioneers concerned with the dating of rocks by radioactive attempted a further reassessment of the aforementioned data decay and served as a world-wide forum through to the bases. Hopefully this iterative process will in time produce an 1950s. The first steps to establish a chronostratigraphic scale accurate time-scale, but at the moment it seems more were taken much earlier at the International Geological realistic to view the suggested summary/compromise time- Congress held in Bologna (Italy) in 1881 and both of these scale as ephemeral. A particularly noticeable aspect of this activities are now co-ordinated through the various Sub- volume is the combined use of ocean floor spreading and commissions of the Commission on Stratigraphy of the reversals of the Earth's magnetic field as secondary time lUGS. keepers. It is already clear that this seconday clock will allow Progress in nuclear physics and the development of new a very fine resolution of Cenozoic time, but it is equally clear tools for isotope research saw the effective birth of isotope that the clock has yet to be accurately calibrated. Con- geology in 1950 (Rankama 1954) and the following decade sideration in this volume is also given to the problems of the saw a major data explosion in this subject. Much of this early Precambrian time-scale and it would seem that following work was essentially geochronometric though not necessarily the deliberations of the Subcommission on Precambrian directed towards the establishment of a geologic time-scale. Stratigraphy and the findings of IGCP Projects 99 and 118 However, the possibility of improving the time-scale, at that (Geochronological Correlation of Precambrian Sediments time the virtual brain child of one man -- Arthur Holmes -- and Volcanics in Stable Zones, and Upper Precambrian resulted in the holding of an interdisciplinary symposium by Correlations respectively) the geological community is on the the Geological Society of London, and the subsequent threshold of a significant advance, albeit one that may be publication in 1964 of The Phanerozoic Time-Scale followed proceded by valuable controversy. by a supplement in 1971. Important aspects of these in- Although there is still room for improvement in the fluencial publications were the inclusions of over 300 items or accuracy and resolution of the time-scale it is nevertheless 'abstracts of published radiometric and stratigraphic data sufficiently accurate to allow very useful estimates of the with comments' which now constitute the foundation data rates at which many geological processes proceed to be bank for virtually all time-scale publications. made, some of the these processes are the subject of papers A notable problem apparent in these pioneering works is in the second part of this volume. the considerable element of uncertainty introduced by It is inevitablethat the task of drawing up a geological differing opinions concerning the numerical values of the time-scale will remain a collaborative and co-operative effort decay constants, particularly for potassium-40 and rubidium- and it is encouraging that the hope expressed in The 87, the two parent isotopes with the widest application in Phanerozoic Time-Scale 'that this co-operative venture will practical geochronometry. The use of the differing decay continue' continues to be realized. The efforts of many of the constants for the same analytical data could result in a authors to produce up to the minute reviews of their subject discrepancy of about 30 Ma for Palaeozoic rocks. Fortunately is particularly appreciated by the sponsors of this symposium. the vigorous persual of this problem by a few researchers, This volume is based on papers presented at a symposium: backed by pressure from the Subcommission on Geo- Geochronology and the Geological Record, held on the llth chronology which circulated questionaires for surveys, and 12th May 1982 in the Scientific Societies Lecture resulted in the presentation at the International Geological Theatre, London and sponsored by the Geological Society of Congress in Sydney, Australia, in 1976 of a 'Convention on London and the Subcommission on Geochronology (IUGS). the Use of Decay Constants in Geochronology and The sponsors are deeply indebted to V.G. Micromass Ltd. Cosmochronology' (Steiger & J~iger 1977) which has since for their generous support and to Dr Gilles Odin who been universally adopted. The effective resolution of this generously made available prior to publication copies of the problem has prompted re-evaluations of the 1964 time-scale, proofs of his work Numerical Dating in Stratigraphy for the notably by Harland, Cox, Llewellyn, Pickton, Smith, and use of contributors to this volume. Waiters (1982) and by Odin (1982). The former work relies heavily on a data base generated by Armstrong (1978) which June 1984 N.J. SNELLING
ARMSTRONG, R. L. 1978. Pre-Cenozoic Phanerozoic time scale- Scale Cambridge University Press, Cambridge. computer file of critical dates and consequences of new and in- ODIN, G. S. (ed.) 1982. Numerical Dating in Stratigraphy. Pt. I progress decay-constant revisions. In: Cohee, G. V. etal (eds), Con- and Pt. II (2 volumes) Wiley, Chicester. tributions to the Geological Time-Scale. Am. Ass. Petrol. RANKAMA, K. 1954. Isotope Geology Pergamon, London. Geol. Studies in Geology No.6..73-91. STEIGER, R. H. & J~,GER, E. 1977. Subcommission on Geo- HARLAND, W. B., Cox, A. V., LLEWELLYN, P. G., PICKTON, chronology: Convention on the use of decay constants in geo- C. A. G., SMITH, A. G. t~ WALTERS, R. 1982. A Geologic Time- and cosmochronology. Earth planet. Sci. Lett., 36, 359-62.