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Sedimentary structures introduces undergraduate students to depositional and also post-depositional sedimentary processes in an structures across a wide range of scales can be interpreted in terms of those processes. Sedimentary structures produced by erosion, deposition and post-depositional change are all clearly explained and related to the processes that formed them. Hydrodynamic and aerodynamic controls on the development of sub-aqueous and aeolian bedforms are discussed, as are the styles of deformation to which sediments can be subjected after deposition.
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Sedimentary structures T H I R D
E D I T I O N
John Collinson Consultant, formerly University of Bergen and Keele University
Nigel Mountney Keele University
David Thompson Formerly Keele University
TERRA
© John D. Collinson, Nigel P. Mountney, David B. Thompson 2006
This book is copyright under the Berne Convention No reproduction without permission All rights reserved
This third edition first published in 2006 by Terra Publishing Second edition published by Unwin Hyman in 1989 First edition published by George Allen & Unwin in 1982 Terra Publishing PO Box 315, Harpenden, Hertfordshire AL5 2ZD, England Telephone: +44 (0)1582 762413 Fax: +44 (0)870 055 8105 Website: www.terrapublishing.net ISBN:
1-903544-19-X 978-1-903544-19-8
ISBN-13:
16 15 14 13 12 11 10 09 08 07 06 10 9 8 7 6 5 4 3 2 1 British Library Cataloguing-in-Publication Data A CIP record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data are available
Typeset in Times New Roman and Helvetica Printed and bound by Gutenberg Press Ltd, Malta
Contents
Preface Acknowledgements
1 Introduction 1.1 The nature of this book 1.2 The wider geological context 1.3 Sedimentary structures and science Study techniques
2 Bedding 2.1 The nature of bedding 2.2 The significance of bedding Study techniques
3 Basic properties of fluids, flows and sediment 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8
Introduction Properties of low-viscosity fluids and flows Waves Properties of sediments moved by flows Erosion Modes of sediment transport Sediment gravity flows Pyroclastic density currents Study techniques
4 Erosional structures 4.1 Introduction 4.2 Sole marks 4.3 Small-scale structures on modern and ancient upper surfaces 4.4 Erosional features in vertical section Study techniques
5 Depositional structures in muds, mudstones and shales
vii ix
5.1 Introduction 5.2 Structures and lamination Study techniques
1 1 3 3 5
67 67 69 73
6 Depositional structures of sands and sandstones 74 6.1 Ripples and cross lamination 6.2 Aqueous dunes, sandwaves, bars and cross bedding 6.3 Aeolian dunes and cross bedding 6.4 Flat beds and parallel lamination 6.5 Undulating smooth surfaces and lamination 6.6 Hummocky and swaley cross stratification 6.7 Massive sand and sandstone beds 6.8 Normally graded beds, inverse grading and the Bouma sequence Study techniques
7 7 15 20
21 21 21 27 29 31 33 34 42 43
7 Depositional structures in gravels, conglomerates and breccias
74 92 111 128 130 131 132 133 136
138
7.1 Introduction 138 7.2 Problems of classification 138 7.3 Morphology and general settings of gravel deposition 140 7.4 Structures and other descriptive features: mode of formation 142 7.5 Processes of formation of mass properties and structures 156 7.6 Uses of structures 161 Study techniques 162
45 45 45 56 59 65
v
CONTENTS
8 Depositional structures of chemical and biological origin 8.1 Introduction 8.2 Chemical precipitation 8.3 Precipitat