Sedimentary Structures: Third Edition

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. THIS FILE CONTAINS ALL PAGES. (NO MISSING PAGES) Preface vii Acknowledgements ix 1 Introduction 1 1.1 The nature of this book 1 1.2 The wider geological context 3 1.3 Sedimentary structures and science 3 Study techniques 5 2 Bedding 7 2.1 The nature of bedding 7 2.2 The significance of bedding 15 Study techniques 20 3 Basic properties of fluids, flows and sediment 21 3.1 Introduction 21 3.2 Properties of low-viscosity fluids and flows 21 3.3 Waves 27 3.4 Properties of sediments moved by flows 29 3.5 Erosion 31 3.6 Modes of sediment transport 33 3.7 Sediment gravity flows 34 3.8 Pyroclastic density currents 42 Study techniques 43 4 Erosional structures 45 4.1 Introduction 45 4.2 Sole marks 45 4.3 Small-scale structures on modern and ancient upper surfaces 56 4.4 Erosional features in vertical section 59 Study techniques 65 5 Depositional structures in muds, mudstones and shales 67 5.1 Introduction 67 5.2 Structures and lamination 69 Study techniques 73 6 Depositional structures of sands and sandstones 74 6.1 Ripples and cross lamination 74 6.2 Aqueous dunes, sandwaves, bars and cross bedding 92 6.3 Aeolian dunes and cross bedding 111 6.4 Flat beds and parallel lamination 128 6.5 Undulating smooth surfaces and lamination 130 6.6 Hummocky and swaley cross stratification 131 6.7 Massive sand and sandstone beds 132 6.8 Normally graded beds, inverse grading and the Bouma sequence 133 Study techniques 136 7 Depositional structures in gravels, conglomerates and breccias 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 8 Depositional structures of chemical and biological origin 163 8.1 Introduction 163 8.2 Chemical precipitation 163 8.3 Precipitation and binding of sediment by organisms 168 8.4 Early cementation 177 8.5 Other bedding phenomena in limestones 180 Study techniques 180 9 Structures created by deformation and disturbance 182 9.1 Introduction 182 9.2 Physically induced soft-sediment deformation 182 9.3 Chemically induced disturbance 204 9.4 Biogenic sedimentary structures: trace fossils 216 Study techniques 242 10 Assemblages of structures and environmental interpretation 243 10.1 Introduction 243 10.2 Mapping of modern environments 243 10.3 Measurement of sections in rock sequences 244 10.4 Interpretation of vertical sequences in rocks 246 10.5 Key stratigraphical surfaces 252 10.6 Interpretation of lateral relationships in sedimentary rocks 253 Study techniques 253 Appendix 1 Directional data: collection, display, analysis and interpretation 257 Appendix 2 Sampling and preserving unconsolidated sediments 262 Appendix 3 Methods for studying present-day environments 263 Appendix 4 Techniques for the study of trace fossils 265 Appendix 5 Techniques for sedimentary logging 266 Appendix 6 Key to common sedimentary lithologies and structures 269 Bibliography 271 Index 281 Thoroughly revised and with many new illustrations, this classic textbook in elementary sedimentology reaches its third edition 20 years after first publication. Particular attention has been paid to recent advances in the understanding of aeolian processes and bedforms, and in the interpretation of trace fossils. The introduction to environmental interpretation has also been developed to reflect recent advances in stratigraphic thinking. Sedimentary structures sets out a clear methodology and philosophy for understanding both present-day sediments and sedimentary rocks as the products of dynamic processes. The book introduces depositional and post-depositional sedimentary processes in an easily accessible way, and shows, across a wide range of scales, how sedimentary structures 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 subaqueous and aeolian bedforms are discussed, as are the styles of deformation to which sediments can be subjected after deposition. Structures that characterize deposition caused by chemical and biologically influenced processes are explained and illustrated, along with the complex effects of chemical changes and of animal and plant activity in modifying sediments after they have been deposited. The book ends with an introduction to the methods and principles of environmental interpretation, for which it provides an invaluable basis. Sedimentary structures is designed for use in introductory courses in universities, colleges and schools. It continues to be enhanced by an abundance of fine illustrations and by its practical hands-on approach to the subject. This edition represents a major revision of the earlier editions, with several chapters mostly rewritten. Many of the illustrations are new and the reference lists have been up-dated and rationalized. As such, this third edition of Sedimentary structures will be warmly welcomed by all readers with interests in sedimentology. A comprehensive introductory treatment of sedimentary structures, characterized by an abundance of clear illustrations and a practical approach to a subject of fundamental importance in the study of sedimentology and related areas of the Earth sciences.