Sedimentology and Sedimentary Basins E-Book

Mike R. Leeder

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 1539

Veröffentlichungsjahr: 2011

Beschreibung

The sedimentary record on Earth stretches back more than 4.3 billion years and is present in more abbreviated forms on companion planets of the Solar System, like Mars and Venus, and doubtless elsewhere. Reading such planetary archives correctly requires intimate knowledge of modern sedimentary processes acting within the framework provided by tectonics, climate and sea or lake level variations. The subject of sedimentology thus encompasses the origins, transport and deposition of mineral sediment on planetary surfaces.

The author addresses the principles of the subject from the viewpoint of modern processes, emphasising a general science narrative approach in the main text, with quantitative background derived in enabling ‘cookie’ appendices. The book ends with an innovative chapter dealing with how sedimentology is currently informing a variety of cognate disciplines, from the timing and extent tectonic uplift to variations in palaeoclimate. Each chapter concludes with a detailed guide to key further reading leading to a large bibliography of over 2500 entries. The book is designed to reach an audience of senior undergraduate and graduate students and interested academic and industry professionals.

Leseprobe

Contents

Preface

Acknowledgements

Part 1: MAKING SEDIMENT

Introduction

Chapter 1 CLASTIC SEDIMENT AS A CHEMICAL AND PHYSICAL BREAKDOWN PRODUCT

1.1 Introduction: clastic sediments—‘accidents’ of weathering

1.2 Silicate minerals and chemical weathering

1.3 Solute flux: rates and mechanisms of silicate chemical weathering

1.4 Physical weathering

1.5 Soils as valves and filters for the natural landscape

1.6 Links between soil age, chemical weathering and weathered-rock removal

1.7 Provenance: siliciclastic sediment-sourcing

Further reading

Chapter 2 CARBONATE, SILICEOUS, IRON-RICH AND EVAPORITE SEDIMENTS

2.1 Marine vs. freshwater chemical composition and fluxes

2.2 The calcium carbonate system in the oceans

2.3 Ooid carbonate grains

2.4 Carbonate grains from marine plants and animals

2.5 Carbonate muds, oozes and chalks

2.6 Other carbonate grains of biological origins

2.7 Organic productivity, sea-level and atmospheric controls of biogenic CaCO3 deposition rates

2.8 CaCO3 dissolution in the deep ocean and the oceanic CaCO3 compensation mechanism

2.9 The carbonate system on land

2.10 Evaporite salts and their inorganic precipitation as sediment

2.11 Silica and pelagic plankton

2.12 Iron minerals and biomineralizers

2.13 Desert varnish

2.14 Phosphates

2.15 Primary microbial-induced sediments: algal mats and stromatolites

Further reading

Chapter 3 SEDIMENT GRAIN PROPERTIES

3.1 General

3.2 Grain size

3.3 Grain-size distributions

3.4 Grain shape and form

3.5 Bulk properties of grain aggregates

Further reading

Part 2: MOVING FLUID

Introduction

Chapter 4 FLUID BASICS

4.1 Material properties of fluids

4.2 Fluid kinematics

4.3 Fluid continuity with constant density

4.4 Fluid dynamics

4.5 Energy, mechanical work and power

Further reading

Chapter 5 TYPES OF FLUID MOTION

5.1 Osborne Reynolds and flow types

5.2 The distribution of velocity in viscous flows: the boundary layer

5.3 Turbulent flows

5.4 The structure of turbulent shear flows

5.5 Shear flow instabilities, flow separation and secondary currents

5.6 Subcritical and supercritical flows: the Froude number and hydraulic jumps

5.7 Stratified flow generally

5.8 Water waves

5.9 Tidal flow—long-period waves

Further reading

Part 3: TRANSPORTING SEDIMENT

Introduction

Chapter 6 SEDIMENT IN FLUID AND FLUID FLOW—GENERAL

6.1 Fall of grains through stationary fluids

6.2 Natural flows carrying particulate material are complex

6.3 Fluids as transporting machines

6.4 Initiation of grain motion

6.5 Paths of grain motion

6.6 Categories of transported sediment

6.7 Some contrasts between wind and water flows

6.8 Cohesive sediment transport and erosion

6.9 A warning: nonequilibrium effects dominate natural sediment transport systems

6.10 Steady state, deposition or erosion: the sediment continuity equation and competence vs. capacity

Further reading

Chapter 7 BEDFORMS AND SEDIMENTARY STRUCTURES IN FLOWS AND UNDER WAVES

7.1 Trinity of interaction: turbulent flow, sediment transport and bedform development

7.2 Water-flow bedforms

7.3 Bedform phase diagrams for water flows

7.4 Water flow erosional bedforms on cohesive beds

7.5 Water wave bedforms

7.6 Combined flows: wave–current ripples and hummocky cross-stratification

7.7 Bedforms and structures formed by atmospheric flows

Further reading

Chapter 8 SEDIMENT GRAVITY FLOWS AND THEIR DEPOSITS

8.1 Introduction

8.2 Granular flows

8.3 Debris flows

8.4 Turbidity flows

8.5 Turbidite evidence for downslope transformation from turbidity to debris flows

Further reading

Chapter 9 LIQUEFACTION, FLUIDIZATION AND SLIDING SEDIMENT DEFORMATION

9.1 Liquefaction

9.2 Sedimentary structures formed by and during liquefaction

9.3 Submarine landslides, growth faults and slumps

9.4 Desiccation and synaeresis shrinkage structures

Further reading

Part 4: MAJOR EXTERNAL CONTROLS ON SEDIMENTATION AND SEDIMENTARY ENVIRONMENTS

Introduction

Chapter 10 MAJOR EXTERNAL CONTROLS ON SEDIMENTATION

10.1 Climate

10.2 Global climates: a summary

10.3 Sea-level changes

10.4 Tectonics

10.5 Sediment yield, denudation rate and the sedimentary record

Further reading

Part 5: CONTINENTAL SEDIMENTARY ENVIRONMENTS

Introduction

Chapter 11 RIVERS

11.1 Introduction

11.2 River networks, hydrographs,patterns and long profiles

11.3 Channel form

11.4 Channel sediment transport processes, bedforms and internal structures

11.5 The floodplain

11.6 Channel belts, alluvial ridges and avulsion

11.7 River channel changes, adjustable variables and equilibrium

11.8 Alluvial architecture: product of complex responses

11.9 Alluvial architecture: scale, controls and time

Further reading

Chapter 12 SUBAERIAL FANS: ALLUVIAL AND COLLUVIAL

12.1 Introduction

12.2 Controls on the size (area) and gradient of fans

12.3 Physical processes on alluvial fans

12.4 Debris-flow-dominated alluvial fans

12.5 Stream-flow-dominated alluvial fans

12.6 Recognition of ancient alluvial fans and talus cones

Further reading

Chapter 13 AEOLIAN SEDIMENTS IN LOW-LATITUDE DESERTS

13.1 Introduction

13.2 Aeolian system state

13.3 Physical processes and erg formation

13.4 Erg margins and interbedform areas

13.5 Erg and draa evolution and sedimentary architecture

13.6 Erg construction, stasis and destruction: climate and sea-level controls

13.7 Ancient desert facies

Further reading

Chapter 14 LAKES

14.1 Introduction

14.2 Lake stratification

14.3 Clastic input by rivers and the effect of turbidity currents

14.4 Wind-forced physical processes

14.5 Temperate lake chemical processes and cycles

14.6 Saline lake chemical processes and cycles

14.7 Biological processes and cycles

14.8 Modern temperate lakes and their sedimentary facies

14.9 Lakes in the East African rifts

14.10 Lake Baikal

14.11 The succession of facies as lakes evolve

14.12 Ancient lake facies

Further reading

Chapter 15 ICE

15.1 Introduction

15.2 Physical processes of ice flow

15.3 Glacier flow, basal lubrication and surges

15.4 Sediment transport, erosion and deposition by flowing ice

15.5 Glacigenic sediment: nomenclature and classification

15.6 Quaternary and modern glacial environments and facies

15.7 Ice-produced glacigenic erosion and depositional facies on land and in the periglacial realm

15.8 Glaciofluvial processes on land at and within the ice-front

15.9 Glacimarine environments

15.10 Glacilacustrine environments

15.11 Glacial facies in the pre-Quaternary geological record: case of Cenozoic Antarctica

Further reading

Part 6: MARINE SEDIMENTARY ENVIRONMENTS

Introduction

Chapter 16 ESTUARIES

16.1 Introduction

16.2 Estuarine dynamics

16.3 Modern estuarine morphology and sedimentary environments

16.4 Estuaries and sequence stratigraphy

Further reading

Chapter 17 RIVER AND FAN DELTAS

17.1 Introduction to river deltas

17.2 Basic physical processes and sedimentation at the river delta front

17.3 Mass movements and slope failure on the subaqueous delta

17.4 Organic deposition in river deltas

17.5 River delta case histories

17.6 River deltas and sea-level change

17.7 Ancient river delta deposits

17.8 Fan deltas

Further reading

Chapter 18 LINEAR SILICICLASTIC SHORELINES

18.1 Introduction

18.2 Beach processes and sedimentation

18.3 Barrier–inlet-spit systems and their deposits

18.4 Tidal flats, salt marsh and chenier ridges

18.5 Ancient clastic shoreline facies

Further reading

Chapter 19 SILICICLASTIC SHELVES

19.1 Introduction: shelf sinks and lowstand bypass

19.2 Shelf water dynamics

19.3 Holocene highstand shelf sediments: general

19.4 Tide-dominated, low river input, highstand shelves

19.5 Tide-dominated, high river input, highstand shelves

19.6 Weather-dominated highstand shelves

Further reading

Chapter 20 CALCIUM-CARBONATE–EVAPORITE SHORELINES, SHELVES AND BASINS

20.1 Introduction: calcium carbonate ‘nurseries’ and their consequences

20.2 Arid carbonate tidal flats, lagoons and evaporite sabkhas

20.3 Humid carbonate tidal flats and marshes

20.4 Lagoons and bays

20.5 Tidal delta and margin-spillover carbonate tidal sands

20.6 Open-shelf carbonate ramps

20.7 Platform margin reefs and carbonate build-ups

20.8 Platform margin slopes and basins

20.9 Carbonate sediments, cycles and sea-level change

20.10 Displacement and destruction of carbonate environments: siliciclastic input and eutrophication

20.11 Subaqueous saltern evaporites

Further reading

Chapter 21 DEEP OCEAN

21.1 Introduction

21.2 Sculpturing and resedimentation: gullies, canyons and basin-floor channels

21.3 Well caught: intraslope basins

21.4 Resedimentation: slides, slumps, linked debris/turbidity flows on the slope and basin plain

21.5 Continental margin deposition: fans and aprons

21.6 Continental margin deposition: turbi-dite pathway systems connecting slopes and basin plains

21.7 Continental margin deposition: thermohaline currents and contourite drifts

21.8 Oceanic biological and chemical processes

21.9 Oceanic pelagic sediments

21.10 Oceanic anoxic pelagic sediments

21.11 Palaeo-oceanography

Further reading

Part 7: ARCHITECTURE OF SEDIMENTARY BASINS

Introduction

Chapter 22 SEDIMENT IN SEDIMENTARY BASINS: A USER’S GUIDE

22.1 Continental rift basins

22.2 Proto-oceanic rifts

22.3 Coastal plains, shelf terraces and continental rises

22.4 Convergent/destructive margin basins: some general comments

22.5 Subduction zones: trenches and trench-slope basins

22.6 Fore-arc basins

22.7 Intra-arc basins

22.8 Back-arc basins

22.9 Foreland basins

22.10 Strike-slip basins

22.11 A note on basin inversion

Further reading

Part 8: TOPICS: SEDIMENT SOLUTIONS TO INTERDISCIPLINARY PROBLEMS

Introduction

Chapter 23 SEDIMENTS SOLVE WIDER INTERDISCIPLINARY PROBLEMS

23.1 Sediments, global tectonics and seawater composition

23.2 Banded Iron Formations, rise of cyanobacteria and secular change in global tectonics

23.3 Tibetan Plateau uplift; palaeoaltimetry and monsoon intensity

23.4 Colorado Plateau uplift and Grand Canyon incision dated by speleothem carbonate

23.5 River channels and large-scale regional tilting

23.6 Regional drainage reversal

23.7 Sediment budgeting and modelling of foreland basins

23.8 Lengthwise growth and fault amalgamation

23.9 Rivers, basement uplifts, tilting and fault growth

23.10 Unsteady strain and the sedimentary response

23.11 Tectonics and climate as depositional controls

23.12 River equilibrium, incision and aggradation—away from the knee-jerk of tectonic explanation

23.13 Integrated sedimentary systems: modelling tectonics, sediment yield and sea level change

23.14 Extraterrestrial sedimentology—atmo-spheric and liquid flows on Mars

23.15 Suborbital surprises: reefs and speleothem as fine-scale tuners of the Pleistocene sea-level curve

23.16 Speleothem: Rosetta stone for past climate

Further reading

COOKIES

MATHS APPENDIX

REFERENCES

COLOUR PLATES FALL BETWEEN

INDEX

This edition first published 2011 © 2011 Mike Leeder First edition published in 1999 by Blackwell Science Ltd.

Blackwell Publishing was acquired by John Wiley & Sons in February 2007. Blackwell’s publishing program has been merged with Wiley’s global Scientific, Technical and Medical business to form Wiley-Blackwell.

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Library of Congress Cataloguing-in-Publication Data

Leeder, M. R. (Mike R.)Sedimentology and sedimentary basins : from turbulence to tectonics / Mike Leeder.–2nd ed. p. cm.Includes index.Summary: “The sedimentary record on Earth stretches back more than 4.3 billion years and is present in more abbreviated forms on companion planets of the Solar System, like Mars and Venus, and doubtless elsewhere. Reading such planetary archives correctly requires intimate knowledge of modern sedimentary processes acting within the framework provided by tectonics, climate and sea or lake level variations. The subject of sedimentology thus encompasses the origins, transport and deposition of mineral sediment on planetary surfaces. The author addresses the principles of the subject from the viewpoint of modern processes, emphasising a general science narrative approach in the main text, with quantitative background derived in enabling ‘cookie’ appendices. The book ends with an innovative chapter dealing with how sedimentology is currently informing a variety of cognate disciplines, from the timing and extent tectonic uplift to variations in palaeoclimate. Each chapter concludes with a detailed guide to key further reading leading to a large bibliography of over 2500 entries. The book is designed to reach an audience of senior undergraduate and graduate students and interested academic and industry professionals.”– Provided by publisher.

Summary: ‘‘The sedimentary record on Earth stretches back more than 4.3 billion years and is present in more abbreviated forms on companion planets of the Solar System, like Mars and Venus, and doubtless elsewhere”– Provided by publisher.

1. Sedimentology. 2. Sedimentary basins. I. Title. QE471.L375 2010552′.5-dc222010023320ISBN 978-1-4443-4992-4 (hbk)—978-1-4051-7783-2 (pbk.)

Preface

World is crazier and more of it than we think, Incorrigibly plural.

Louis MacNeice, ‘Snow’, Collected Poems, Faber

The predecessors to this book, Sedimentology: Process and Product (Allen and Unwin, 1982) and Sedimentology and Sedimentary Basins: from Turbulence to Tectonics (Blackwell Science 1999) are out of print and partly outdated respectively. I have received much feedback from many persons who have used these books over the years and the current version is intendedto trytorecapture the spiritofadynamic and widely applied science. Reasons of space have pre-ventedme from dealing with the subjects of diagenesis and the transformation of sediment to sedimentary rock. I have replaced these with chapters linking sedimentology to climate, sea-level change, tectonics, sedimentary basin architecture and their role in solving interdisciplinary problems. I feel somewhat uneasy about the omission, but it strikes me that the subject of diagenesis has become so based upon the physics of subsurface water flow and the chemistry of low temperature water–rock interactions that the difference of emphasis is too much to encompass within the present text.

Progress over the past decade has been breathtaking. Take some examples: the flow dynamics of opaque mud suspensions can now be monitered by acoustic Doppler probes; knowledge of deep-sea environments has been revolutionized by improved sea-bed imaging; sedimentological reactions to climatic and sea-level change have proved robust and sedimentology contributes vitally to the understanding of the evolution of sedimentary basins, from the birth, life and death of bounding faults to the climatic and palaeontological record contained within them. Further, carbonate sediments and their contained O2 stable isotopes play a key role in establishing ancient oceanic composition (evaporite fluid inclusions), the palaeoaltimetry of high mountains and plateau (calcisols) and the determination of ancient climate (speleothem). All this means that sedimentology is not something that can be done in isolation; the holistic approach is that which I have taken in this book, one based on a thorough understanding of modern processes that I trust will propel the reader into an enthusiasm for the subject and a sense of its place in the wider scheme of earth sciences, specifically in attempts to read the magnificent rock record.

Who do I expect to be reading this book? You will have completed an introductory course in general geology, earth or environmental sciences, and perhaps a more specific basic one in sedimentology or sedimentary geology. You will thus know the basic sediment and sedimentary rock types and also know something of the place of the subject within the broader earth and environmental sciences. You will have enough basic science background to understand, if not feel exactly on top of, Newton’s laws, basic thermodynamics and aqueous chemistry. Though mathematically challenged, like many earth scientists including myself, you should at least know where to find out how to manipulate equations to a reducible form. I make no apology for spending a little more time with basic fluid dynamics than with the thermodynamics. This is not because I find one more interesting or important than the other—it’s just that most high school leavers and graduating university students (even those of physics) do little in the way of fluid mechanics in their syllabi nowadays and it seemed that the theme of ‘sedimentological fluid dynamics’ is just such a place to set up some sort of foundation. Philosophically you should want to reduce the complicated natural world to an orderly scheme, but at the same time not want to miss out on the romance and poetry of an unclassifiable subject. You will be someone who enjoys talking and arguing with a variety of other earth science specialists.

Just a few final notes are in order.

More involved derivations of essential physical and chemical concepts are to be found in the end section labelled ‘Cookies’. These are meant to be helpful for intellectual health. There is also a short mathematical refresher appendix. I would appreciate it if readers let me know of any mistakes or symbol typos I may have made as I hope to live long enough to make another edition, someday.I have tried my best to reference major developments correctly at the end of chapters, to make sure the source of specific case histories can be traced and to respect historical precedence and discoveries. References are given in abbreviated form, but quite sufficient to be of full use in rapid web-based search vehicles like Web of Science.Many graphs with data points have been generalized to ‘clouds’ or ‘envelopes’ of data points—if you wish toget the original data,gobacktothe citedreferences.

Thanks to colleagues and friends who either directly, through conversation, or indirectly through me reading their works, have inspired my continued interest in sedimentology and its many applications. I would like in particular to thank long-time collaborators and friends Jan Alexander, Julian Andrews, Jim Best, John Bridge, Rob Gawthorpe and Greg Mack for keeping my mind stretched over past years. I also extend my heartfelt thanks to former faculty colleagues at the fine Universities of Leeds and East Anglia where I have spent my professional life, together with my ex-undergraduate and graduate students, for keep-ingmeonmytoes.IamgratefultoDrJenny Mason for writing the sections on terrestrial carbonates (section 2.9), the role of speleothems in palaeoclimatic studies (section 23.18) and, with Dr James Hodson, for compiling the reference list. Finally, thanks to the whole production team at Wiley-Blackwell and to Ian Francis for his gentlemanly encouragement to complete this project and for putting up with some delays over the past 4 years as I periodically got on with my research and real life instead!

Mike Leeder

Brooke, Norwich

January, 2010

Acknowledgements

Permission has been granted (or at time of going to press has been requested) to reproduce or alter illustrative materials from the following publishers and holders of copyright:

American Association of Petroleum Geologists: Figs 17.6, 17.10, 21.24

American Geophysical Union: Part 6 Fig. 1; Figs 2.3, 6.5,6.9, 6.15, 66, 8.7, 10.2, 10.14, 14.15, 15.4, 15.7, 16.1, 16.2, 16.6, 16.7, 18.2, 18.5, 18.10, 18.15, 19.9, 21.1, 21.26.

American Mineralogical Society: Figs. 1.3, 1.6.

American Society of Civil Engineers: Figs. 6.8, 11.5, 12.7.

Annual Reviews of Earth and Planetary Science: Fig. 11.6.

Arnold: Fig. 13.2.

Balkema: Fig. 7.27.

Cambridge University Press: Figs. 4.14, 5.8, 5.10–13, 5.15–16, 7.11, 8.1, 8.16, 10.7, 15.1, 15.8.

Chapman & Hall: Figs. 1.4, 19.8

Elsevier: Figs: Part 6 Fig. 2, 1.2, 1.5, 1.8–9, 1.14–1.16, 1.18–19, 2.1, 2.14, 7.6, 7.9, 7.15–16, 7.21, 7.25, 7.32, 7.40, 7.46, 8.6, 11.4, 11.22, 13.4, 17.7–9, 17.12, 19.1, 21.27–28, 23.13.

Geological Society of America: Figs. 1.13, 1.17, 2.2, 2.17, 8.11, 10.5–6, 10.10, 11.3, 12.4, 12.6, 12.9, 14.14, 15.3, 16.13, 17.2–3, 20.1, 20.30, 21.2, 21.14, 22.6–7, 22.11, 22.21.

Geological Society of London: Figs 10.4, 10.13, 11.14–15, 13.15, 21.17, 21.32, 22.12

Harcourt, Brace, Jovanovich: Fig 2.9.

Harper Collins: Figs 7.4, 8.22.

International Association of Sedimentologists/Sedimentology/Basin Research: Figs. 6.6–7, 6.18, 7.2, 7.7, 7.12–13, 7.22–23, 7.26, 7.31, 7.39, 7.43, 7.45, 7.47–49, 8.3, 8.8, 8.14, 8.17–21, 9.3, 9.6, 9.10–11, 11.11–12, 11.16–19, 11.21, 11.29, 12.10, 13.6–14, 13.17, 14.3, 14.6, 14.8–9, 14.11–13, 14.16, 14.18, 15.10, 15.12–13, 16.4–5, 16.11–12, 17.13, 17.18, 17.27–28, 18.9, 18.14, 18.16, 18.18, 19.10–12, 19.16, 20.2–3, 20.6, 20.14–15, 20.25–27, 20.31–35, 20.38–40, 21.8, 21.10–11, 21.13, 21.16, 21.18–20, 21.25, 21.29–30, 22.13–14, 22.23–27, 22.32–34.

Johns Hopkins Press: Figs 22.9–11.

Journal of Geology: Figs 1.10, 2.7.

McGraw-Hill: Fig. 4.1.

Nature: Figs. 5.20, 7.37, 8.24–26, 10.16, 15.2, 15.5–6, 21.33, 23.2, 23.21, 23.23

Oxford University Press: Figs. 4.9, 5.14.

Pergamon: Figs. 5.21, 5.25.

Princeton University Press: Figs. 4.2, 5.24.

Royal Society of London: Figs. 6.11, 23.3.

Society of Economic Palaeontologists & Mineralogists/Journal of Sedimentary Research: Figs. Part 6 Fig. 2, 3.3, 6.1, 6.16, 7.14, 7.28–30, 7.34, 7.38, 7.44, 10.11, 11.8, 11.24–28, 12.1, 13.16, 14.7, 14.19, 15.11, 16.8–10, 17.4, 17.11, 17.14, 17.16–17, 17.20–25, 18.3, 18.6–8, 18.11, 18.13, 18.20–21, 19.2–3, 19.15, 20.4, 20.8, 20.12–13, 20.16–21, 20.24, 20.28–29, 20.36–37, 20.41, 21.3–7, 21.9, 21.12, 21.15, 21.21, 21.2–23, 22.18, 22.29–31, Cookie 8 Fig. 3.

Soil Science Society of America: Fig. 6.4.

Springer Verlag: Fig. 20.22.

Van Nostrand Reinhold: Figs. 5.2, 5.7, 5.19.

Wiley: Figs. 6.12, 6.14, 11.13, 18.4, 22.8–9, 22.15–17, 22.19–20, 22.22.

Part 1

MAKING SEDIMENT

… the soil which has kept breaking away from the high lands during these ages and these disasters, forms no pile of sediment worth mentioning, as in other regions, but keeps sliding away ceaselessly and disappearing in the deep.

Plato, Critias, Vol. 9, Loeb Classical Library

Introduction

The noun sediment comes to the English language from the Latin root sedimentum, meaning settling or sinking down,aform ofthe verb sedere,to sit orsettle. In earth and environmental sciences, sediment has a wide context that includes many forms of organic and mineral matter. In Part 1 we look more deeply at the origins of the sediment that occurs on and under the surface of the solid planets and which may be used to infer past environmental conditions and changes. Sediment accumulations may be grandly viewed as the great stratal archive of past surface environments, or more basically as‘dirt’. There has been sediment on the surface of the Earth since the Archaean, with the oldest known sediment grains dating from at least 4.4Ga (Part 1 Fig. 1). Sediment also mantles the surface of many other planets and their satellites, notably Mars, Venus and Saturn’s moon, Titan.

In scientific usage, Earth’s sediment is best divided into three end-members:

clastic—originating from pre-existing rock outside a depositional area as transported grains, the commonest being mineral silicate grains, known widely as siliciclastic sediment;chemical—being the result of inorganic or organically mediated chemical precipitation within the depositional area;biological—derived from skeletal material associated with living tissues.

These simple divisions are robust enough to include even the highly esoteric sediment forms that are turning up in the wider Solar System, like the solid ice particles transported and deposited by liquid methane on Titan.Ofcourse there are unusual, hybridormixed origins for some sediment but these can easily be accommodated (e.g. bioclastic, volcaniclastic). Note that the classification is restricted to grains that were sedimented; there are sedimentary horizons in the stratigraphic record that originated as precipitates below the deposited sediment surface, often bacteri-ally controlled. These were never sedimented as such and are considered as secondary or diagenetic sediments that post-dated physical deposition of host primary sediment. Deposited sediment accumulates as successive layers, termed strata, and such deposits as a whole are said to be stratified. The succession of strata in any given deposit is controlled by environmental factors and their correct interpretation involves a deep understanding of how present and past environments have evolved over time.

The chemical and biochemical processes that produce sediment also give other soluble byproducts; these chemical species control oceanic and atmospheric composition and provide long-term sourcing for base cations that nourish plant life and counteract acid deposition in temperate forested catchments. Chemical earth-surface processes have undoubtedly changed over deep geological time, in response to atmospheric and hydrological changes, whilst biological processes have changed hand-in-hand with organic evolution. By this view, sediment production is an accident of weathering and evolution—a waste product. Ever since the Archaean, the planet has ‘learnt’ how to cope with this waste, just like it has with the waste oxygen produced during plant photosynthesis. There was no predeterminism associated with the processes of sediment production on early Earth or any other planet. Sediment simply fell out (forgive the pun) of the rock cycle in which primary rock is chemically and physically altered. Compare for example sediment on the Moon with the Earth.In the former the sediment is a fragmented remnant from past meteoritic impact events. In the latter sediment is highly varied in its origins, composition, size and physical properties. Its role as an accidental part of the Rock Cycle establishes sedimentology as a fundamental part of Earth System Science. Indeed, as one nice semi-popular review entitled it a decade ago (Stanley & Hardie, 1999), from the point-of-view of calcareous sediment, ‘Hypercalcification: Paleontology Links Plate Tectonics and Geochemistry to Sedimentology’. We shall examine such grand claims later in this book (Chapter 23).

Part1 Fig. 1 Image of the famous Jack Hills’zircons from the Cryptic Era of the Hadean Eon (discovery paper of Wilde et al., 2001). The location is ∼800 km north of Perth in Western Australia in the Narryer Gneiss Terrane of the Yilgarn Craton, a group of folded and metamorphosed supracrustal rocks thought to have originally contained sedimentary siliciclastic rocks. Detrital zircons with ages greater than 4 billion years old occur here, the oldest being 4.4 Ga (±8 million), the oldest dated material originating on Earth. The source is a metamorphosed conglomerate considered to have an age ∼3.0Ga, so the detrital zircons are sourced from pre-existing rocks, probably subduction zone plutonic igneous intrusions which were then weathered and the resultant sediment deposited as sedimentary rock. The zircons are evidence for the existence of continental-type crust on the surface of the Earth during the Hadean Eon, contrasting with earlier ideas on the earliest phase of Earth’s history in which continental crust was thought absent and plate tectonics inoperative until much later. Additionally, oxygen isotopic ratios in the zircons provide evidence for the presence of liquid water on the Earth’s surface at this time. The image isa general photograph of a pristine Jack Hills’zircon (Curtin University website). Longest axis of crystal ∼250μm.

Chapter 1

CLASTIC SEDIMENT AS A CHEMICAL AND PHYSICAL BREAKDOWN PRODUCT

Few ken to whom this muckle monument stands, Some general or admiral I’ve nae doot, On the hill-top whaur weather lang syne Has blotted its inscribed palaver oot.

Hugh MacDiarmid, ‘The Monument’, 1936, Complete Poems, Vol. 1, Carcanet, 1993.

1.1 Introduction: clastic sediments—‘accidents’ of weathering

Terrestrial clastic sedimentary rocks are usually quite different in their composition from the igneous and metamorphic rocks that sourced them. This is because they are derived from an altered regolith with a soil profile produced by chemical weathering of pristine bedrock and the source of mineral grains for such sediment. For example, feldspar is the commonest mineral in bedrock of the Earth’s continental crust (about 60% of the total) but quartz is usually predominant in clastic sediments and sedimentary rocks. Despite this difference the principle of conservation of mass tells us that for all elements present in the exposed crust and released by weathering, exactly the same levels of abundance must occur in the average total sedimentary mass. Thus the average chemical composition of all sediments is roughly that of the igneous rock, granodiorite, representing the mean composition of middle to upper continental crust.

It is traditional to divide rock weathering into physical and chemical components, but in reality the two are inextricably interlinked. Water is the chief reactant and plays a dual role since it also transports away both dissolved and solid weathering products. Earthispresentlyuniqueinits abundanceofwater and water vapour, yet Mars also had an earlier watery prehistory. It is easy to take water for granted, the deceptively simple molecule H2O has remarkable properties of great importance for rock and mineral weathering (Cookie 1). These include its solvent and hydration properties, wetting effects due to high saturation and anomalous decreaseofdensityatlow liquid temperatures and after freezing. An outline of the near-surface terrestrial hydrological cycle is given in .