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Sedimentology and Stratigraphy

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  • Front Matter
    • COMPANION CD-ROM
    • Contents
    • Preface
      • AN UNDERGRADUATE TEXT
      • DEFINITIONS OF TERMS
      • REFERENCES
      • CROSS-REFERENCING AND THE CD-ROM
    • Acknowledgements
  • 1 Introduction: Sedimentology and Stratigraphy
    • 1.1 SEDIMENTARY PROCESSES
    • 1.2 SEDIMENTARY ENVIRONMENTS AND FACIES
      • Fig. 1.1 A modern depositional environment: a sandy river channel and vegetated floodplain.
      • Fig. 1.2 Sedimentary rocks interpreted as the deposits of a river channel (the lens of sandstones in the centre right of the view) scoured into mudstone deposited on a floodplain (the darker, thinly bedded strata below and to the side of the sandstone lens).
    • 1.3 THE SPECTRUM OF ENVIRONMENTS AND FACIES
    • 1.4 STRATIGRAPHY
    • 1.5 THE STRUCTURE OF THIS BOOK
    • FURTHER READING
  • 2 Terrigenous Clastic Sediments: Gravel, Sand and Mud
    • 2.1 CLASSIFICATION OF SEDIMENTS AND SEDIMENTARY ROCKS
      • Fig. 2.1 A classification scheme for sediments and sedimentary rocks.
      • Terrigenous clastic material
      • Carbonates
      • Evaporites
      • Volcaniclastic sediments
      • Others
      • 2.1.1 Terrigenous clastic sediments and sedimentary rocks
        • Fig. 2.2 The Udden-Wentworth grain-size scale for clastic sediments: the clast diameter in millimetres is used to define the different sizes on the scale, and the phi values are -log2 of the grain diameter.
      • 2.1.2 The Udden-Wentworth grain-size scale
    • 2.2 GRAVEL AND CONGLOMERATE
      • Fig. 2.3 A conglomerate composed of well-rounded pebbles.
      • Fig. 2.4 A conglomerate (or breccia) made up of angular clasts.
      • 2.2.1 Composition of gravel and conglomerate
      • 2.2.2 Texture of conglomerate
        • Fig. 2.5 Nomenclature used for mixtures of gravel, sand and mud in sediments and sedimentary rock.
        • Fig. 2.6 A clast-supported conglomerate: the pebbles are all in contact with each other.
        • Fig. 2.7 A matrix-supported conglomerate: each pebble is surrounded by matrix.
      • 2.2.3 Shapes of clasts
        • Fig. 2.8 The shape of clasts can be considered in terms of four end members, equant, rod, disc and blade. Equant and disc-shaped clasts are most common.
        • Fig. 2.9 A conglomerate bed showing imbrication of clasts due to deposition in a current flowing from left to right.
        • Fig. 2.10 The relationship between imbrication and flow direction as clasts settle in a stable orientation.
    • 2.3 SAND AND SANDSTONE
      • 2.3.1 Detrital mineral grains in sands and sandstones
        • Quartz
        • Feldspar
        • Mica
        • Heavy minerals
        • Miscellaneous minerals
      • 2.3.2 Other components of sands and sandstones
        • Lithic fragments
        • Biogenic particles
        • Authigenic minerals
        • Matrix
      • 2.3.3 Sandstone nomenclature and classification
        • Fig. 2.11 The Pettijohn classification of sandstones, often referred to as a ‘Toblerone plot’ (Pettijohn 1975).
      • 2.3.4 Petrographic analysis of sands and sandstones
        • Fig. 2.12 A photomicrograph of a sandstone: the grains are all quartz but appear different shades of grey under crossed polars due to different orientations of the grains.
        • The petrographic microscope
      • 2.3.5 Thin-section analysis of sandstones
        • Grain shape
        • Relief
        • Cleavage
        • Colour and opacity
        • Pleochroism
        • Birefringence colours
        • Angle of extinction
        • Twinning of crystals
      • 2.3.6 The commonest minerals in sedimentary rocks
        • Fig. 2.13 The optical properties of the minerals most commonly found in sedimentary rocks.
        • Quartz
        • Feldspars
        • Micas
        • Other silicate minerals
        • Glauconite
        • Carbonate minerals
        • Oxides and sulphides
        • Heavy minerals
      • 2.3.7 Lithic grains
        • Chert and chalcedony
        • Organic material
        • Sedimentary rock fragments
        • Igneous rock fragments
        • Metamorphic rock fragments
      • 2.3.8 Matrix and cement
      • 2.3.9 Practical thin-section microscopy
        • Point counting
    • 2.4 CLAY, SILT AND MUDROCK
      • 2.4.1 Definitions of terms in mudrocks
      • 2.4.2 Silt and siltstone
      • 2.4.3 Clay minerals
        • Fig. 2.14 The crystal lattice structure of some of the more common clay minerals.
      • 2.4.4 Petrographic analysis of clay minerals
      • 2.4.5 Clay particle properties
    • 2.5 TEXTURES AND ANALYSIS OF TERRIGENOUS CLASTIC SEDIMENTARY ROCKS
      • Clasts and matrix
      • Sorting
        • Fig. 2.15 Graphic illustration of sorting in clastic sediments. The sorting of a sediment can be determined precisely by granulometric analysis, but a visual estimate is more commonly carried out.
      • Clast roundness
        • Fig. 2.16 Roundness and sphericity estimate comparison chart (from Pettijohn et al. 1987).
      • Clast sphericity
      • Fabric
      • 2.5.1 Granulometric and clast-shape analysis
        • Fig. 2.17 Histogram, frequency distribution and cumulative frequency curves of grain size distribution data. Note that the grain size decreases from left to right.
      • 2.5.2 Clast-shape analysis
      • 2.5.3 Maturity of terrigenous clastic material
        • Textural maturity
          • Fig. 2.18 Flow diagram of the determination of the textural maturity of a terrigenous clastic sediment or sedimentary rock.
        • Mineralogical maturity
      • 2.5.4 Cycles of sedimentation
    • 2.6 TERRIGENOUS CLASTIC SEDIMENTS: SUMMARY
    • FURTHER READING
  • 3 Biogenic, Chemical and Volcanogenic Sediments
    • 3.1 LIMESTONE
      • 3.1.1 Carbonate mineralogy
        • Calcite
        • Aragonite
        • Dolomite
        • Siderite
      • 3.1.2 Carbonate petrography
      • 3.1.3 Biomineralised carbonate sediments
        • Fig. 3.1 Types of bioclast commonly found in limestones and other sedimentary rocks.
        • Fig. 3.2 Bioclastic debris on a beach consisting of the hard calcareous parts of a variety of organisms.
        • Carbonate-forming animals
          • Fig. 3.3 Fossil gastropod shells in a limestone.
        • Carbonate-forming plants
          • Fig. 3.4 Mounds of cyanobacteria form stromatolites, which are bulbous masses of calcium carbonate material at various scales: (top) modern stromatolites; (bottom) a cross-section through ancient stromatolites.
      • 3.1.4 Non-biogenic constituents of limestone
        • Fig. 3.5 Non-biogenic fragments that occur in limestones.
      • 3.1.5 Carbonate muds
      • 3.1.6 Classification of limestones
        • Fig. 3.6 The Dunham classification of carbonate sedimentary rocks (Dunham 1962) with modifications by Embry & Klovan (1971). This scheme is the most commonly used for description of limestones in the field and in hand specimen.
      • 3.1.7 Petrographic analysis of carbonate rocks
        • Fig. 3.7 The calcareous hard parts of organisms may be made up of aragonite, calcite in either its low- or highmagnesium forms, or mixtures of minerals.
    • 3.2 EVAPORITE MINERALS
      • Fig. 3.8 The proportions of the principal ions in seawater of normal salinity and ‘average’ river water. (Data from Krauskopf 1979).
      • Fig. 3.9 The proportions of minerals precipitated by the evaporation of seawater of average composition.
      • 3.2.1 Gypsum and anhydrite
      • 3.2.2 Halite
        • Fig. 3.10 White halite precipitated on the shores of the Dead Sea, Jordan, which has a higher concentration of ions than normal seawater.
      • 3.2.3 Other evaporite minerals
    • 3.3 CHERTS
    • 3.4 SEDIMENTARY PHOSPHATES
    • 3.5 SEDIMENTARY IRONSTONE
      • 3.5.1 Iron minerals in sediments
      • 3.5.2 Formation of ironstones
      • 3.5.3 Banded Iron Formations
        • Fig. 3.11 Thinly bedded banded iron formation (BIF) composed of alternating layers of iron-rich and silica-rich rock.
      • 3.5.4 Ferromanganese deposits
    • 3.6 CARBONACEOUS (ORGANIC) DEPOSITS
      • 3.6.1 Modern organic-rich deposits
      • 3.6.2 Coal
      • 3.6.3 Oil shales and tar sands
    • 3.7 VOLCANICLASTIC SEDIMENTARY ROCKS
      • 3.7.1 Types of volcaniclastic rocks
      • 3.7.2 Nomenclature of volcaniclastic rocks
        • Fig. 3.12 (a) The classification of volcaniclastic sediments and sedimentary rocks based on the grain size of the material. (b) Nomenclature used for loose ash and consolidated tuff with different proportions of lithic, vitric and crystal components.
      • 3.7.3 Recognition of volcaniclastic material
    • FURTHER READING
  • 4 Processes of Transport and Sedimentary Structures
    • 4.1 TRANSPORT MEDIA
      • Gravity
      • Water
      • Air
      • Ice
      • Dense sediment and water mixtures
    • 4.2 THE BEHAVIOUR OF FLUIDS AND PARTICLES IN FLUIDS
      • 4.2.1 Laminar and turbulent flow
        • Fig. 4.1 Laminar and turbulent flow of fluids through a tube.
      • 4.2.2 Transport of particles in a fluid
        • Fig. 4.2 Particles move in a flow by rolling and saltating (bedload) and in suspension (suspended load).
      • 4.2.3 Entraining particles in a flow
        • Fig. 4.3 Flow of a fluid through a tapered tube results in an increase in velocity at the narrow end where a pressure drop results.
        • Fig. 4.4 The lift force resulting from the Bernoulli effect causes grains to be moved up from the base of the flow.
      • 4.2.4 Grain size and flow velocity
        • Fig. 4.5 The Hjülstrom diagram shows the relationship between the velocity of a water flow and the transport of loose grains. Once a grain has settled it requires more energy to start it moving than a grain that is already in motion. The cohesive properties of clay particles mean that fine-grained sediments require relatively high velocities to re-erode them once they are deposited, especially once they are compacted. (From Press & Siever 1986.)
      • 4.2.5 Clast-size variations: graded bedding
        • Fig. 4.6 Normal and reverse grading within individual beds and fining-up and coarsening-up patterns in a series of beds.
      • 4.2.6 Fluid density and particle size
    • 4.3 FLOWS, SEDIMENT AND BEDFORMS
      • Fig. 4.7 Layers within a flow and flow surface roughness: the viscous sublayer, the boundary layer within the flow and the flow depth.
      • 4.3.1 Current ripples
        • Fig. 4.8 Flow over a bedform: imaginary streamlines within the flow illustrate the separation of the flow at the brink of the bedform and the attachment point where the streamline meets the bed surface, where there is increased turbulence and erosion. A separation eddy may form in the lee of the bedform and produce a minor counter-current (reverse) flow.
        • Fig. 4.9 Current ripple cross-lamination in fine sandstone: the ripples migrated from right to left. The coin is 20 mm in diameter.
        • Fig. 4.10 Migrating straight crested ripples form planar cross-lamination. Sinuous or isolated (linguoid or lunate) ripples produce trough cross-lamination. (From Tucker 1991.)
        • Current ripples and cross-lamination
          • Fig. 4.11 In plan view current ripples may have straight, sinuous or isolated crests.
        • Creating and preserving cross-lamination
          • Fig. 4.12 Climbing ripples: in the lower part of the figure, more of the stoss side of the ripple is preserved, resulting in a steeper ‘angle of climb’.
        • Constraints on current ripple formation
      • 4.3.2 Dunes
        • Fig. 4.13 Dune bedforms in an estuary: the most recent flow was from left to right and the upstream side of the dunes is covered with current ripples.
        • Fig. 4.14 Graphs of subaqueous ripple and subaqueous dune bedform wavelengths and heights showing the absence of overlap between ripple and dune-scale bedforms. (From Collinson et al. 2006.)
        • Dunes and cross-bedding
          • Fig. 4.15 Migrating straight crested dune bedforms form planar cross-bedding. Sinuous or isolated (linguoid or lunate) dune bedforms produce trough cross-bedding. (From Tucker 1991.)
          • Fig. 4.16 Subaqueous dune bedforms in a braided river.
          • Fig. 4.17 The patterns of cross-beds are determined by the shape of the bedforms resulting from different flow conditions.
          • Fig. 4.18 Planar tabular cross-stratification with tangential bases to the cross-beds (the scale bar is in inches and is 100 mm long).
        • Constraints on the formation of dunes
      • 4.3.3 Bar forms
      • 4.3.4 Plane bedding and planar lamination
        • Fig. 4.19 Horizontal lamination in sandstone beds.
      • 4.3.5 Supercritical flow
      • 4.3.6 Bedform stability diagram
        • Fig. 4.20 A bedform stability diagram which shows how the type of bedform that is stable varies with both the grain size of the sediment and the velocity of the flow.
    • 4.4 WAVES
      • 4.4.1 Formation of wave ripples
        • Fig. 4.21 The formation of wave ripples in sediment is produced by oscillatory motion in the water column due to wave ripples on the surface of the water. Note that there is no overall lateral movement of the water, or of the sediment. In deep water the internal friction reduces the oscillation and wave ripples do not form in the sediment.
        • Fig. 4.22 Forms of wave ripple: rolling grain ripples produced when the oscillatory motion is capable only of moving the grains on the bed surface and vortex ripples are formed by higher energy waves relative to the grain size of the sediment.
      • 4.4.2 Characteristics of wave ripples
        • Fig. 4.23 Wave ripples in sand seen in plan view: note the symmetrical form, straight crests and bifurcating crest lines.
        • Fig. 4.24 Internal stratification in wave ripples showing cross-lamination in opposite directions within the same layer. The wavelength may vary from a few centimetres to tens of centimetres.
        • Fig. 4.25 Wave ripple cross-lamination in sandstone (pen is 18 cm long).
      • 4.4.3 Distinguishing wave and current ripples
    • 4.5 MASS FLOWS
      • 4.5.1 Debris flows
        • Fig. 4.26 A muddy debris flow in a desert wadi.
        • Fig. 4.27 A debris-flow deposit is characteristically poorly sorted, matrix-supported conglomerate.
      • 4.5.2 Turbidity currents
        • Fig. 4.28 A turbidity current is a turbulent mixture of sediment and water that deposits a graded bed – a turbidite.
        • Low- and medium-density turbidity currents
          • Fig. 4.29 The ‘Bouma sequence’ in a turbidite deposit.
          • Fig. 4.30 Proximal to distal changes in the deposits formed by turbidity currents. The lower, coarser parts of the Bouma sequence are only deposited in the more proximal regions where the flow also has a greater tendency to scour into the underlying beds.
        • High-density turbidity currents
          • Fig. 4.31 A high-density turbidite deposited from a flow with a high proportion of entrained sediment.
      • 4.5.3 Grain flows
    • 4.6 MUDCRACKS
      • Fig. 4.32 Mudcracks caused by subaerial desiccation of mud.
      • Fig. 4.33 Syneresis cracks in mudrock, believed to be formed by subaqueous shrinkage.
    • 4.7 EROSIONAL SEDIMENTARY STRUCTURES
      • Fig. 4.34 Sole marks found on the bottoms of beds: flute marks and obstacle scours are formed by flow turbulence; groove and bounce marks are formed by objects transported at the base of the flow.
      • Scour marks
      • Tool marks
    • 4.8 TERMINOLOGY FOR SEDIMENTARY STRUCTURES AND BEDS
      • Fig. 4.35 Bed thickness terminology.
      • Fig. 4.36 Terminology used for sets and co-sets of cross-stratification.
      • Fig. 4.37 Lenticular, wavy and flaser bedding in deposits that are mixtures of sand and mud.
    • 4.9 SEDIMENTARY STRUCTURES AND SEDIMENTARY ENVIRONMENTS
    • FURTHER READING
  • 5 Field Sedimentology, Facies and Environments
    • 5.1 FIELD SEDIMENTOLOGY
      • 5.1.1 Field equipment
      • 5.1.2 Field studies: mapping and logging
    • 5.2 GRAPHIC SEDIMENTARY LOGS
      • Fig. 5.1 An example of a graphic sedimentary log: this form of presentation is widely used to summarise features in successions of sediments and sedimentary rocks.
      • 5.2.1 Drawing a graphic sedimentary log
        • Fig. 5.2 Examples of patterns and symbols used on graphic sedimentary logs.
      • 5.2.2 Presentation of graphic sedimentary logs
        • Fig. 5.3 A proforma sheet for constructing graphic sedimentary logs.
      • 5.2.3 Other graphical presentations: sketches and photographs
        • Fig. 5.4 An example of an annotated sketch illustrating sedimentary features observed in the field.
        • Fig. 5.5 A field photograph of sedimentary rocks: an irregular lower surface of the thick sandstone unit in the upper part of the cliff marks the base of a river channel.
    • 5.3 PALAEOCURRENTS
      • 5.3.1 Palaeocurrent indicators
      • 5.3.2 Measuring palaeocurrents
        • Fig. 5.6 The true direction of dip of planes (e.g. planar cross-beds) cannot be determined from a single vertical face (faces A or B): a true dip can be calculated from two different apparent dip measurements or measured directly from the horizontal surface (T).
        • Fig. 5.7 Trough cross-bedding seen in plan view: flow is interpreted as being away from the camera.
      • 5.3.3 Presentation and analysis of directional data
        • Fig. 5.8 A rose diagram is used to graphically summarise directional data such as palaeocurrent information: the example on the right shows data indicating a flow to the south west.
      • 5.3.4 Calculating the mean of palaeocurrent data
        • Fig. 5.9 Directions measured from palaeoflow can be considered in terms of ‘x’ and ‘y’ co-ordinates: see text for discussion.
    • 5.4 COLLECTION OF ROCK SAMPLES
      • 5.4.1 Provenance studies
        • Fig. 5.10 Some of the heavy minerals that can be used as provenance indicators.
    • 5.5 DESCRIPTION OF CORE
      • Fig. 5.11 When drilling through strata it is possible to recover cylinders of rock that are cut vertically to reveal the details of the beds.
    • 5.6 INTERPRETING PAST DEPOSITIONAL ENVIRONMENTS
      • 5.6.1 The concept of ‘facies’
      • 5.6.2 Facies analysis
      • 5.6.3 Facies associations
        • Fig. 5.12 A graphic sedimentary log with facies information added. The names for facies are usually descriptive. Facies codes are most useful where they are an abbreviation of the facies description. The use of columns for each facies allows for trends and patterns in facies and associations to be readily recognised.
        • Fig. 5.13 A summary of the principal sedimentary environments.
      • 5.6.4 Facies sequences/successions
      • 5.6.5 Facies names and facies codes
    • 5.7 RECONSTRUCTING PALAEOENVIRONMENTS IN SPACE AND TIME
      • 5.7.1 Palaeoenvironments in space
      • 5.7.2 Palaeoenvironments in time
    • 5.8 SUMMARY: FACIES AND ENVIRONMENTS
    • FURTHER READING
  • 6 Continents: Sources of Sediment
    • 6.1 FROM SOURCE OF SEDIMENT TO FORMATION OF STRATA
      • Fig. 6.1 The pathway of processes involved in the formation of a succession of clastic sedimentary rocks, part of the rock cycle.
    • 6.2 MOUNTAIN-BUILDING PROCESSES
      • Fig. 6.2 The boundaries of the present-day principal tectonic plates.
    • 6.3 GLOBAL CLIMATE
      • Fig. 6.3 The present-day world climate belts.
    • 6.4 WEATHERING PROCESSES
      • Fig. 6.4 The principal weathering processes and their controls.
      • 6.4.1 Physical weathering
        • Freeze–thaw action
          • Fig. 6.5 Frost shattering of a boulder (50 cm across) in a polar climate setting.
        • Salt growth
        • Temperature changes
      • 6.4.2 Chemical weathering
        • Solution
        • Hydrolysis
        • Oxidation
      • 6.4.3 The products of weathering
        • Fig. 6.6 The relative stabillty of common silicate minerals under chemical weathering.
      • 6.4.4 Soil development
        • Fig. 6.7 An in situ soil profile with a division into different horizons according to presence of organic matter and degree of breakdown of the regolith.
    • 6.5 EROSION AND TRANSPORT
      • 6.5.1 Erosion and transport under gravity
        • Downslope movement
          • Fig. 6.8 Mechanisms of gravity-driven transport on slopes. Rock falls and slides do not necessarily include water, whereas slumps, debris flows and turbidity currents all include water to increasing degrees.
        • Scree and talus cones
          • Fig. 6.9 A scree slope or talus cone in a mountain area with strong physical weathering.
      • 6.5.2 Erosion and transport by water
      • 6.5.3 Erosion and transport by wind
      • 6.5.4 Erosion and transport by ice
    • 6.6 DENUDATION AND LANDSCAPE EVOLUTION
      • 6.6.1 Topography and relief
      • 6.6.2 Climate controls on denudation processes
        • Wet tropical regions
        • Arid subtropical regions
        • Polar and cold mountain regions
        • Temperate regions
      • 6.6.3 Bedrock lithology and denudation
        • Fig. 6.10 Erosion by solution in beds of limestone results in a karst landscape.
        • Fig. 6.11 Badlands scenery formed by the erosion of weak mudrock beds.
      • 6.6.4 Soils and denudation
      • 6.6.5 Vegetation and denudation
        • Fig. 6.12 The development of land plants through time: grasses, which are very effective at binding soil and stabilising the land surface, did not become widespread until the mid-Cenozoic.
    • 6.7 TECTONICS AND DENUDATION
      • Fig. 6.13 Uplift due to thickening of the crust followed by erosion results in isostatic compensation as the load of the rock mass eroded is removed. If the erosion is uneven then locally the removal of mass from valleys can result in uplift of the mountain peaks between.
      • Fig. 6.14 The rain shadow effect in mountain belts: moisture in air blown from the sea falls as rain as the air mass cools over a mountain range.
    • 6.8 MEASURING RATES OF DENUDATION
    • 6.9 DENUDATION AND SEDIMENT SUPPLY: SUMMARY
    • FURTHER READING
  • 7 Glacial Environments
    • 7.1 DISTRIBUTION OF GLACIAL ENVIRONMENTS
      • Fig. 7.1 Snowfall adds to the mass of a glacier in the accumulation zone and as the glacier advances downslope it enters the ablation zone where mass is lost due to ice melting. Glacial advance or retreat is governed by the balance between these two processes.
      • Fig. 7.2 Hills and ridges of bare rock (known as nunataks) surrounded by glaciers and ice sheets in a high-latitude polar glacial area.
      • Fig. 7.3 Floating ice, including icebergs, is formed by calving of ice from a glacier.
    • 7.2 GLACIAL ICE
      • 7.2.1 Thermal regimes of glaciers
        • Fig. 7.4 The thermal regimes of glaciers are determined by the climatic setting: glaciers frozen to bedrock tend to occur in polar regions, while temperate glaciers occur in mountains in lower latitudes.
    • 7.3 GLACIERS
      • Fig. 7.5 A valley glacier in a temperate mountain region partially covered by a carapace of detritus.
      • 7.3.1 Erosional glacial features
      • 7.3.2 Transport by continental glaciers
      • 7.3.3 Deposition by continental glaciers
        • Fig. 7.6 Till deposits result from the accumulation of debris above, below and in front of a glacier.
      • 7.3.4 Characteristics of glacially transported material
    • 7.4 CONTINENTAL GLACIAL DEPOSITION
      • Fig. 7.7 Glacial landforms and glacial deposits in continental glaciated areas.
      • Fig. 7.8 Graphic sedimentary log illustrating some of the deposits of continental glaciers.
      • 7.4.1 Moraines
        • Fig. 7.9 A lateral moraine left by the retreat of a valley glacier.
        • Fig. 7.10 A dark ridge of material within a valley glacier that will form a medial moraine when the ice retreats (viewed from the air).
      • 7.4.2 Other glacial landforms
      • 7.4.3 Outwash plains
      • 7.4.4 Periglacial areas
        • Fig. 7.11 In periglacial areas, freeze–thaw processes in the surface of the permafrost form polygonal patterns.
    • 7.5 MARINE GLACIAL ENVIRONMENTS
      • Fig. 7.12 At continental margins in polar areas, continental ice feeds floating ice sheets that eventually melt releasing detritus to form a till sheet and calve to form icebergs, which may carry and deposit dropstones.
      • Fig. 7.13 An ice shelf at the edge of a continental glaciated area.
      • 7.5.1 Erosional features associated with marine glaciers
      • 7.5.2 Marine glacial deposits
        • Fig. 7.14 Glaciomarine deposits are typically laminated mudrocks with sparse coarser debris derived from icebergs.
    • 7.6 DISTRIBUTION OF GLACIAL DEPOSITS
    • 7.7 ICE, CLIMATE AND TECTONICS
      • 7.7.1 Glaciation and global climate
      • 7.7.2 Glacial rebound – isostasy
    • 7.8 SUMMARY OF GLACIAL ENVIRONMENTS
      • Characteristics of glacial deposits
    • FURTHER READING
  • 8 Aeolian Environments
    • 8.1 AEOLIAN TRANSPORT
      • 8.1.1 Global wind patterns
        • Fig. 8.1 The distribution of high- and low-pressure belts at different latitudes creates wind patterns that are deflected by the Coriolis force.
      • 8.1.2 Aeolian transport processes
    • 8.2 DESERTS AND ERGS
      • Fig. 8.2 Pebbles in a stony desert with a shiny desert varnish of iron and manganese oxides.
    • 8.3 CHARACTERISTICS OF WIND-BLOWN PARTICLES
      • 8.3.1 Texture of aeolian particles
      • 8.3.2 Composition of aeolian deposits
    • 8.4 AEOLIAN BEDFORMS
      • Fig. 8.3 Aeolian ripples, dunes and draas are three distinct types of aeolian bedform.
      • 8.4.1 Aeolian ripple bedforms
        • Fig. 8.4 Aeolian ripples form by sand grains saltating: finer grains are winnowed from the crests creating a slight inverse grading between the trough and the crest of the ripple that may be preserved in laminae.
        • Fig. 8.5 Aeolian ripples in modern desert sands: the pen is 18 cm long.
      • 8.4.2 Aeolian dune bedforms
        • Fig. 8.6 Aeolian dunes migrate as sand blown up the stoss (upwind) side is either blown off the crest to fall as grainfall on the lee side or moves by grain flow down the lee slope.
        • Fig. 8.7 Aeolian ripples superimposed on an aeolian dune.
        • Fig. 8.8 Grain flow on the lee slope of an aeolian dune.
        • Fig. 8.9 Four of the main aeolian dune types, their forms determined by the direction of the prevailing wind(s) and the availability of sand. The small ‘rose diagrams’ indicate the likely distribution of palaeowind indicators if the dunes resulted in cross-bedded sandstone.
        • Fig. 8.10 Sand supply and the variability of prevailing wind directions control the types of dunes formed.
        • Fig. 8.11 Aeolian dune cross-bedding in sands deposited in a desert: the view is approximately 5 m high.
      • 8.4.3 Draa bedforms
      • 8.4.4 Palaeowind directions
    • 8.5 DESERT ENVIRONMENTS
      • Fig. 8.12 Depositional environments in arid regions: coarse material is deposited on alluvial fans, sand accumulates to form aeolian dunes and occasional rainfall feeds ephemeral lakes where mud and evaporite minerals are deposited.
      • Fig. 8.13 Graphic sedimentary log of the arid-zone environments shown in Fig. 8.12.
      • 8.5.1 Water table
        • Fig. 8.14 The preservation of aeolian dune deposits is influenced by the level of the groundwater table: if the water table is high the interdune areas are wet and the sand is not reworked by the wind.
      • 8.5.2 Global climate variations
        • Fig. 8.15 The global distribution of modern deserts: most lie within 40° of the Equator.
        • Fig. 8.16 During glacial periods the regions of polar high pressure are larger, creating stronger pressure gradients and hence stronger winds. In the absence of large high pressure areas at the poles in interglacial periods the pressure gradients are weaker and winds are consequently less strong.
      • 8.5.3 Colour in desert sediments
      • 8.5.4 Life in deserts and fossils in aeolian deposits
    • 8.6 AEOLIAN DEPOSITS OUTSIDE DESERTS
      • 8.6.1 Aeolian dust deposits
      • 8.6.2 Aeolian sands in other environments
        • Beach dunes
        • Periglacial deposits
    • 8.7 SUMMARY
      • Characteristics of aeolian deposits
    • FURTHER READING
  • 9 Rivers and Alluvial Fans
    • 9.1 FLUVIAL AND ALLUVIAL SYSTEMS
      • Fig. 9.1 The geomorphological zones in alluvial and fluvial systems: in general braided rivers tend to occur in more proximal areas and meandering rivers occur further downstream.
      • 9.1.1 Catchment and discharge
      • 9.1.2 Flow in channels
        • Fig. 9.2 A sandy river channel and adjacent overbank area: the river is at low-flow stage exposing areas of sand deposited in the channel.
    • 9.2 RIVER FORMS
      • Fig. 9.3 Several types of river can be distinguished, based on whether the river channel is straight or sinuous (meandering), has one or multiple channels (anastomosing), and has in-channel bars (braided). Combinations of these forms can often occur.
      • 9.2.1 Bedload (braided) rivers
        • Fig. 9.4 Main morphological features of a braided river. Deposition of sand and/or gravel occurs on mid-channel bars.
        • Fig. 9.5 Mid-channel gravel bars in a braided river.
        • Fig. 9.6 A schematic graphic sedimentary log of braided river deposits.
        • Fig. 9.7 Sandy dune bedforms on a mid-channel bar in a braided river.
        • Fig. 9.8 This large braided river has moved laterally from right to left.
        • Fig. 9.9 Depositional architecture of a braided river: lateral migration of the channel and the abandonment of bars leads to the build-up of channel-fill successions.
      • 9.2.2 Mixed load (meandering) rivers
        • Fig. 9.10 Flow in a river follows the sinuous thalweg resulting in erosion of the bank in places.
        • Fig. 9.11 Main morphological features of a meandering river. Deposition occurs on the point bar on the inner side of a bend while erosion occurs on the opposite cut bank. Levees form when flood waters rapidly deposit sediment close to the bank and crevasse splays are created when the levee is breached.
        • Fig. 9.12 The point bars on the inside bends of this meandering river have been exposed during a period of low flow in the channel.
        • Fig. 9.13 A schematic graphic sedimentary log of meandering river deposits.
        • Fig. 9.14 A pale band across the inside of this meander bend marks the path of a chute channel that cuts across the point bar.
        • Fig. 9.15 Depositional architecture of a meandering river: sandstone bodies formed by the lateral migration of the river channel remain isolated when the channel avulses or is cut-off to form an oxbow lake.
        • Fig. 9.16 A channel is commonly not filled with sand: in this case the form of a channel is picked out by steep banks on either side, but the fill of the channel is mainly mud.
      • 9.2.3 Ephemeral rivers
      • 9.2.4 Channel-filling processes
      • 9.2.5 Trends in fluvial systems
    • 9.3 FLOODPLAIN DEPOSITION
    • 9.4 PATTERNS IN FLUVIAL DEPOSITS
      • 9.4.1 Architecture of fluvial successions
        • Fig. 9.17 The architecture of fluvial deposits is determined by the rates of subsidence and frequency of avulsion.
      • 9.4.2 Palaeocurrents in fluvial systems
      • 9.4.3 Fluvial deposits and palaeogeography
    • 9.5 ALLUVIAL FANS
      • Fig. 9.18 Alluvial fans in the Death Valley, USA, a region with a hot, arid climate.
      • Fig. 9.19 A colluvial fan, a mixture of scree and debris flows in a cold, relatively dry setting in the Arctic.
      • 9.5.1 Morphology of alluvial fans
        • Fig. 9.20 Types of alluvial fan: debris-flow dominated, sheetflood and stream-channel types – mixtures of these processes can occur on a single fan.
      • 9.5.2 Processes of deposition on alluvial fans
        • Subaerial debris flows
          • Fig. 9.21 Schematic sedimentary logs through debris-flow, sheetflood and stream-channel alluvial fan deposits.
          • Fig. 9.22 A debris flow on an alluvial fan: the conglomerate is poorly sorted, with the larger clasts completely surrounded by a matrix of finer sediment.
        • Sheetflood deposition
          • Fig. 9.23 Sheetflood deposits on an alluvial fan showing well-developed stratification.
        • Fluvial deposits forming alluvial fans
      • 9.5.3 Modification of alluvial fan deposits
      • 9.5.4 Controls on alluvial fan deposition
    • 9.6 FOSSILS IN FLUVIAL AND ALLUVIAL ENVIRONMENTS
    • 9.7 SOILS AND PALAEOSOLS
      • 9.7.1 Soils
        • Fig. 9.24 Twelve major soil types recognised by the US Soil Survey.
      • 9.7.2 Palaeosols
        • Fig. 9.25 A calcrete forms by precipitation of calcium carbonate within a soil in an arid or semi-arid environment.
    • 9.8 FLUVIAL AND ALLUVIAL FAN DEPOSITION: SUMMARY
      • Characteristics of fluvial and alluvial fan deposits
    • FURTHER READING
  • 10 Lakes
    • 10.1 LAKES AND LACUSTRINE ENVIRONMENTS
      • 10.1.1 Lake formation
      • 10.1.2 Lake hydrology
        • Fig. 10.1 Hydrological regimes of lakes.
        • Fig. 10.2 A lake basin supplied by a river in the foreground, with outflow through a sill to the sea in the distance.
    • 10.2 FRESHWATER LAKES
      • 10.2.1 Hydrology of freshwater lakes
        • Fig. 10.3 The thermal stratification of fresh lake waters results in a more oxic, upper layer, the epilimnion, and a colder, anoxic lower layer, the hypolimnion. Sedimentation in the lake is controlled by this density stratification above and below the thermocline.
      • 10.2.2 Lake margin clastic deposits
        • Fig. 10.4 Facies distribution in a freshwater lake with dominantly clastic deposition.
        • Fig. 10.5 A schematic graphic sedimentary log through clastic deposits in a freshwater lake.
      • 10.2.3 Deep lake facies
      • 10.2.4 Lacustrine carbonates
        • Fig. 10.6 Facies distributions in a freshwater lake with carbonate deposition.
        • Fig. 10.7 A saline lake, Mono Lake, California: the mineral deposit mounds are associated with underground spring waters.
    • 10.3 SALINE LAKES
      • Fig. 10.8 Three general types of saline lake can be distinguished on the basis of their chemistry.
    • 10.4 EPHEMERAL LAKES
      • Fig. 10.9 A salt crust of minerals formed by evaporation in an ephemeral lake.
      • Fig. 10.10 When an ephemeral lake receives an influx of water and sediment, mud is deposited from suspension to form a thin bed that is overlain by evaporite minerals as the water evaporates. Repetitions of this process create a series of couplets of mudstone and evaporite.
    • 10.5 CONTROLS ON LACUSTRINE DEPOSITION
    • 10.6 LIFE IN LAKES AND FOSSILS IN LACUSTRINE DEPOSITS
    • 10.7 RECOGNITION OF LACUSTRINE FACIES
      • Characteristics of lake deposits
    • FURTHER READING
  • 11 The Marine Realm: Morphology and Processes
    • 11.1 DIVISIONS OF THE MARINE REALM
      • Fig. 11.1 A cross-section from the continental shelf through the continental slope and rise down to the abyssal plain.
      • Fig. 11.2 Depth-related divisions of the marine realm: (a) broad divisions are defined by water depth; (b) the shelf is described in terms of the depth to which different processes interact with the sea floor, and the actual depths vary according to the characteristics of the shelf.
    • 11.2 TIDES
      • 11.2.1 Tidal cycles
        • Fig. 11.3 The gravitational force of the Sun and Moon act on the Earth and on anything on the surface, including the water masses in oceans.
      • 11.2.2 Tidal ranges
        • Fig. 11.4 The North Sea of northwest Europe has a variable tidal range along different parts of the bordering coasts. Amphidromic points mark the centres of cells of rotary tides that affect the shallow sea.
      • 11.2.3 Characteristics of tidal currents
        • Fig. 11.5 During the diurnal tidal cycle the direction of flow reverses from ebb (offshore) to flood (onshore). The current velocity also varies from peaks at the mid points of ebb and flood flow, reducing to zero at high and low tide slack water before accelerating again.
      • 11.2.4 Sedimentary structures generated by tidal currents
        • Bipolar cross-stratification
          • Fig. 11.6 Features that indicate tidal influence of transport and deposition: (a) herringbone cross-stratification; (b) mud drapes on cross-bedding formed during the slack water stages of tidal cycles; (c) reactivation surfaces formed by erosion of part of a bedform when a current is reversed.
          • Fig. 11.7 Herringbone cross-stratification in sandstone beds (width of view 1.5 m).
        • Mud drapes on cross-strata
          • Fig. 11.8 Cross-bedded sandstone in sets 35 cm thick with the surfaces of individual cross-beds picked out by thin layers of mud. Mud drapes on cross-beds are interpreted as forming during slack water stages in the tidal cycle.
        • Reactivation surfaces
          • Fig. 11.9 A reactivation surface within cross-bedded sands is a minor erosion surface truncating some of the cross-beds.
        • Tidal bundles
    • 11.3 WAVE AND STORM PROCESSES
      • 11.3.1 Storms
      • 11.3.2 Tsunami
    • 11.4 THERMO-HALINE AND GEOSTROPHIC CURRENTS
      • Fig. 11.10 The main geostrophic current pathways (thermo-haline circulation patterns) affecting the modern oceans. Sink points in the North Atlantic are due to input of cold glacial meltwater from the Greenland ice-cap.
    • 11.5 CHEMICAL AND BIOCHEMICAL SEDIMENTATION IN OCEANS
      • 11.5.1 Glaucony and glauconite
      • 11.5.2 Phosphorites
      • 11.5.3 Organic-rich sediments: black shales
    • 11.6 MARINE FOSSILS
    • 11.7 TRACE FOSSILS
      • Fig. 11.11 Classification of trace fossils based on interpretation of the activity of the organism. (Adapted from Seilacher 2007.)
      • 11.7.1 Trace fossils in palaeoenvironmental analysis
      • 11.7.2 Trace fossil assemblages
        • Fig. 11.12 Assemblages of trace fossil forms and their relationship to the major divisions of the marine realm. (Adapted from Pemberton et al. 1992.) The assemblages are named after characteristic ichnofauna and the ‘type’ ichnofossil does not need to be present in the assemblage.
        • Fig. 11.13 The characteristics of trace fossils are influenced by the nature of the substrate. Boring organisms cut sharp-sided traces into solid rock or cemented sea floors (hardgrounds). Semiconsolidated surfaces (firm-grounds) result in well-defined burrows.
        • Fig. 11.14 Examples of common trace fossils: (a) bird footprint; (b) bivalve borings into rock; (c) vertical burrows in sandstone (Skolithos); (d) large crustacean burrow (Ophiomorpha); (e) complex burrows (Thalassanoides); (f) Zoophycos; (g) Palaeodictyon; (h) Helmenthoides.
      • 11.7.3 Bioturbation
      • 11.7.4 Trace fossils and rates of sedimentation
    • 11.8 MARINE ENVIRONMENTS: SUMMARY
    • FURTHER READING
  • 12 Deltas
    • 12.1 RIVER MOUTHS, DELTAS AND ESTUARIES
      • Fig. 12.1 A delta fed by a river prograding into a body of water.
    • 12.2 TYPES OF DELTA
      • Fig. 12.2 The forms of modern deltas: (a) the Nile delta, the ‘original’ delta, (b) the Mississippi delta, a river-dominated delta, (c) the Rhone delta, a wave-dominated delta, (d) the Ganges delta, a tide-dominated delta.
      • Fig. 12.3 Classification of deltas taking grain size, and hence sediment supply mechanisms, into account. (Modified from Orton & Reading 1993.)
      • Fig. 12.4 Controls on delta environments and facies. (Adapted from Elliott 1986a.)
      • Fig. 12.5 Delta deposition can be divided into two subenvironments, the delta top and the delta front.
    • 12.3 DELTA ENVIRONMENTS AND SUCCESSIONS
      • 12.3.1 Delta-top subenvironments
      • 12.3.2 Delta-front subenvironments
      • 12.3.3 Deltaic successions
        • Fig. 12.6 A cross-section across a delta lobe: progradation results in a coarseningup succession.
    • 12.4 VARIATIONS IN DELTA MORPHOLOGY AND FACIES
      • 12.4.1 Effects of grain size: fine-grained deltas
        • Fig. 12.7 Differences in the grain size of the sediment supplied affect the form of a delta: (a) a high proportion of suspended load results in a relatively small mouth bar deposited from bedload and extensive delta-front and prodelta deposits; (b) a higher proportion of bedload results in a delta with a higher proportion of mouth bar gravels and sands.
      • 12.4.2 Effects of grain size: coarse-grained deltas
      • 12.4.3 Water depth: shallow- and deep-water deltas
        • Fig. 12.8 (a) A delta prograding into shallow water will spread out as the sediment is redistributed by shallow-water processes to form extensive mouth-bar and delta-front facies. (b) In deeper water the mouth bar is restricted to an area close to the river mouth and much of the sediment is deposited by mass-flow processes in deeper water.
        • Fig. 12.9 A schematic sedimentary log of a sandy delta prograding into shallow water.
        • Fig. 12.10 A schematic sedimentary log of a sandy delta prograding into a deep-water basin.
      • 12.4.4 Coarse-grained deep-water deltas
        • Fig. 12.11 A modern Gilbert-type coarsegrained delta.
        • Fig. 12.12 Gilbert-type deltas are coarse-grained deltas that prograde into deep water. They display a distinctive pattern of steeply-dipping foreset beds sandwiched between horizontal topset and bottomset strata.
        • Fig. 12.13 A schematic sedimentary log of a Gilbert-type coarse-grained delta deposit.
        • Fig. 12.14 A Gilbert-type coarse-grained delta exposed in a cliff over 500m high. The exposure is made up mostly of foreset deposits dipping at around 30°: horizontal topset strata form the top of the cliff and the toes of the foreset beds pass into gently dipping bottomset facies.
      • 12.4.5 Process controls: river-dominated deltas
        • Fig. 12.15 A river-dominated delta with the distributary channels building out as extensive lobes due to the absence of reworking by wave and tide processes. Low-energy, interdistributary bays are a characteristic of river-dominated deltas.
        • Fig. 12.16 When a delta channel avulses a new lobe starts to build out at the new location of the channel mouth. The abandoned lobe subsides by dewatering until completely submerged. Through time the channel will eventually switch back to a position overlapping the former delta lobe. This results in a series of delta-lobe successions, each coarsening-up.
        • Fig. 12.17 A schematic graphic sedimentary log of river-dominated delta deposits.
      • 12.4.6 Process controls: wave-dominated deltas
        • Fig. 12.18 A wave-dominated delta formed where wave activity reworks the sediment brought to the delta front to form coastal sand bars and extensive mouth-bar deposits.
        • Fig. 12.19 Sand bars at the mouth of a wave-dominated delta.
        • Fig. 12.20 A schematic graphic sedimentary log of wave-dominated delta deposits.
      • 12.4.7 Process controls: tide-dominated deltas
        • Fig. 12.21 A tide-dominated delta in a macrotidal regime will show extensive reworking of the delta front by tidal currentsand the delta top will have a region of intertidal deposition.
        • Fig. 12.22 A schematic graphic sedimentary log of tide-dominated delta deposits.
    • 12.5 DELTAIC CYCLES AND STRATIGRAPHY
      • Fig. 12.23 Delta cycles: the facies succession preserved depends on the location of the vertical profile relative to the depositional lobe of a delta.
    • 12.6 SYNDEPOSITIONAL DEFORMATION IN DELTAS
    • 12.7 RECOGNITION OF DELTAIC DEPOSITS
    • FURTHER READING
  • 13 Clastic Coasts and Estuaries
    • 13.1 COASTS
      • Fig. 13.1 Reflective coasts are usually erosional with steep beaches and a narrow surf zone. Dissipative coasts may be depositional, with sand deposited on a gently sloping foreshore.
      • 13.1.1 Erosional coastlines
        • Fig. 13.2 An erosional coastline: wave action has eroded the cliff and left a wave-cut platform of eroded rock on the beach.
      • 13.1.2 Depositional coastlines
    • 13.2 BEACHES
      • Fig. 13.3 Morphological features of a beach comprising a beach foreshore and backshore separated by a berm; beach dune ridges are aeolian deposits formed of sand reworked from the beach.
      • Fig. 13.4 Foreshore-dipping and backshore-dipping stratification in sands on a beach barrier bar.
      • 13.2.1 Beach dune ridges
        • Fig. 13.5 A beach dune ridge formed by sand blown by the wind from the shoreline onto the coast to form aeolian dunes, here stabilised by grass.
        • Fig. 13.6 A schematic graphic sedimentary log of sandy beach deposits.
      • 13.2.2 Coastal plains and strand plains
        • Fig. 13.7 A wave-dominated coastline with a coastal plain bordered by a sandy beach: chenier ridges are relics of former beach strand plains.
    • 13.3 BARRIER AND LAGOON SYSTEMS
      • 13.3.1 Barriers
        • Fig. 13.8 A wave-dominated coastline with a beach-barrier bar protecting a lagoon.
        • Fig. 13.9 Beach-barrier bars along a wave-dominated coastline.
        • Fig. 13.10 Morphological features of a coastline influenced by wave processes and tidal currents.
      • 13.3.2 Lagoons
        • Fig. 13.11 A schematic graphic sedimentary log of clastic lagoon deposits.
    • 13.4 TIDES AND COASTAL SYSTEMS
      • 13.4.1 Microtidal coasts
      • 13.4.2 Mesotidal coasts
      • 13.4.3 Macrotidal coasts
    • 13.5 COASTAL SUCCESSIONS
      • Fig. 13.12 A schematic graphic sedimentary log of a transgressive coastal succession.
    • 13.6 ESTUARIES
      • 13.6.1 Wave-dominated estuaries
        • Fig. 13.13 Distribution of depositional settings in a wave-dominated estuary.
        • Fig. 13.14 A wave-dominated estuary, with an extensive beach barrier protecting a lagoonal area.
        • Bay-head delta
        • Central lagoon
        • Beach barrier
        • Successions in wave-dominated estuaries
          • Fig. 13.15 A graphic sedimentary log of wave-dominated estuary deposits.
      • 13.6.2 Tide-dominated estuaries
        • Fig. 13.16 Distribution of depositional settings in a tidally dominated estuary.
        • Fig. 13.17 A tidally dominated estuarine environment with banks of sand covered with dune bedforms exposed at low tide.
        • Tidal channels
        • Tidal flats
        • Tidal bars
        • Successions in tide-dominated estuaries
          • Fig. 13.18 A graphic sedimentary log of tidal estuary deposits.
      • 13.6.3 Recognition of estuarine deposits: summary
    • 13.7 FOSSILS IN COASTAL AND ESTUARINE ENVIRONMENTS
      • Characteristics of coastal and estuarine systems
      • Beach/barrier systems
      • Lagoons
      • Tidal channel systems
      • Tidal mudflats
    • FURTHER READING
  • 14 Shallow Sandy Seas
    • 14.1 SHALLOW MARINE ENVIRONMENTS OF TERRIGENOUS CLASTIC DEPOSITION
      • 14.1.1 Sediment supply to shallow seas
      • 14.1.2 Characteristics of shallow marine sands
      • 14.1.3 Shallow marine clastic environments
    • 14.2 STORM-DOMINATED SHALLOW CLASTIC SEAS
      • 14.2.1 Facies distribution across a storm-dominated shelf
        • Shoreface
          • Fig. 14.1 Characteristics of a storm-dominated shelf environment.
        • Offshore transition zone
          • Fig. 14.2 Hummocky–swaley cross-stratification, a sedimentary structure that is thought to be characteristic of storm conditions on a shelf.
          • Fig. 14.3 An example of hummocky cross-stratified sandstone with very well-defined, undulating laminae. The bed is 30 cm thick.
          • Fig. 14.4 A bed deposited by storm processes. The base (bottom of the photograph) of the bed has a sharp erosional contact with underlying mudrocks. Planar lamination is overlain by hummocky cross-stratification and capped by wave-rippled sandstone and mudstone (just below the adhesive tape roll, 8 cm across).
        • Offshore
      • 14.2.2 Characteristics of a storm-dominated shallow-marine succession
        • Fig. 14.5 A schematic graphic sedimentary log of a storm-dominated succession.
        • Fig. 14.6 The strata in the hillside are a succession passing up from offshore mudstones (bottom left), to thin-bedded sandstone of the offshore transition zone up to the cliff-forming shoreface sandstones.
      • 14.2.3 Mud-dominated shelves
    • 14.3 TIDE-DOMINATED CLASTIC SHALLOW SEAS
      • 14.3.1 Deposition on tide-dominated shelves
        • Offshore sand ridges
          • Fig. 14.7 Sandwaves, sand ridges and sand ribbons in shallow, tidally influenced shelves and epicontinental seas.
        • Tidal sandwaves and sand ribbons
          • Fig. 14.8 Large-scale cross-stratification formed by the migration of sandwaves in a tidally influenced shelf environment.
          • Fig. 14.9 Bioturbated, cross-bedded sandstones deposited on a tidally influenced shelf.
      • 14.3.2 Characteristics of tide-dominated shallow-marine successions
        • Fig. 14.10 A schematic sedimentary log through a tidally influenced shelf succession.
    • 14.4 RESPONSES TO CHANGE IN SEA LEVEL
    • 14.5 CRITERIA FOR THE RECOGNITION OF SANDY SHALLOW-MARINE SEDIMENTS
    • FURTHER READING
  • 15 Shallow Marine Carbonate and Evaporite Environments
    • 15.1 CARBONATE AND EVAPORITE DEPOSITIONAL ENVIRONMENTS
      • 15.1.1 Controls on carbonate sedimentation
        • Isolation from clastic supply
        • Shallow marine waters
          • Fig. 15.1 The relationship between water depth and biogenic carbonate productivity, which is greatest in the photic zone.
      • 15.1.2 Controls on evaporite sedimentation
      • 15.1.3 Morphologies of shallow marine carbonate-forming environments
        • Fig. 15.2 The types of carbonate platform in shallow marine environments.
      • 15.1.4 Carbonate grain types and assemblages
        • Fig. 15.3 Different groups of organisms have been important producers of carbonate sedimentary material through the Phanerozoic; limestones of different ages therefore tend to have different biogenic components.
    • 15.2 COASTAL CARBONATE AND EVAPORITE ENVIRONMENTS
      • 15.2.1 Beaches
      • 15.2.2 Beach barrier lagoons
        • Fig. 15.4 Morphological features of a carbonate coastal environment with a barrier protecting a lagoon.
        • Carbonate lagoons
        • Arid lagoons
          • Fig. 15.5 A carbonate-dominated coast with a barrier island in an arid climatic setting: evaporation in the protected lagoon results in increased salinity and the precipitation of evaporite minerals in the lagoon.
      • 15.2.3 Supratidal carbonates and evaporites
        • Supratidal carbonate flats
          • Fig. 15.6 In arid coastal settings a sabkha environment may develop. Evaporation in the supratidal zone results in saline water being drawn up through the coastal sediments and the precipitation of evaporite minerals within and on the sediment surface.
        • Arid sabkha flats
      • 15.2.4 Intertidal carbonate deposits
        • Fig. 15.7 Tide-influenced coastal carbonate environments.
    • 15.3 SHALLOW MARINE CARBONATE ENVIRONMENTS
      • 15.3.1 Carbonate sand shoals
      • 15.3.2 Reefs
        • Fig. 15.8 Modern coral atolls.
        • Fig. 15.9 Modern corals in a fringing reef. The hard parts of the coral and other organisms form a boundstone deposit.
        • Reef-forming organisms
          • Fig. 15.10 The type and abundance of carbonate reefs has varied through the Phanerozoic (data from Tucker, 1992).
          • Fig. 15.11 The core of a Devonian reef flanked by steeply dipping forereef deposits on the right-hand side of the exposure.
        • Reef structures
          • Fig. 15.12 Facies distribution in a reef complex.
        • Reef settings
          • Fig. 15.13 Reefs can be recognised as occurring in three settings: (a) barrier reefs form offshore on the shelf and protect a lagoon behind them, (b) fringing reefs build at the coastline and (c) patch reefs or atolls are found isolated offshore, for instance on a seamount.
        • Reefs as palaeoenvironmental indicators
        • Cessation of reef development
      • 15.3.3 Carbonate mud mounds
      • 15.3.4 Outer shelf and ramp carbonates
        • Fig. 15.14 Cliffs of Cretaceous Chalk.
      • 15.3.5 Platform margins and slopes
    • 15.4 TYPES OF CARBONATE PLATFORM
      • Fig. 15.15 Generalised facies distributions on carbonate platforms: (a) ramps, (b) non-rimmed shelves and (c) rimmed shelves.
      • 15.4.1 Carbonate ramps
        • Distribution of facies on a carbonate ramp
        • Carbonate ramp succession
          • Fig. 15.16 Schematic graphic log of a carbonate ramp succession.
      • 15.4.2 Non-rimmed carbonate shelves
        • Fig. 15.17 Schematic graphic log of a non-rimmed carbonate shelf succession.
      • 15.4.3 Rimmed carbonate shelves
        • Distribution of facies on a carbonate rimmed shelf
        • Rimmed carbonate shelf successions
          • Fig. 15.18 Schematic graphic log of a rimmed carbonate shelf succession.
      • 15.4.4 Epicontinental (epeiric) platforms
      • 15.4.5 Carbonate banks and atolls
    • 15.5 MARINE EVAPORITES
      • 15.5.1 Platform evaporites
      • 15.5.2 Evaporitic basins (saline giants)
        • Fig. 15.19 Settings where barred basins can result in thick successions of evaporites.
        • Fig. 15.20 (a) A barred basin, ‘bulls-eye’ pattern model of evaporite deposition; (b) a barred basin ‘teardrop’ pattern model of evaporite deposition.
    • 15.6 MIXED CARBONATE–CLASTIC ENVIRONMENTS
    • FURTHER READING
  • 16 Deep Marine Environments
    • 16.1 OCEAN BASINS
      • Fig. 16.1 Deep water environments are floored by ocean crust and are the most widespread areas of deposition worldwide.
      • 16.1.1 Morphology of ocean basins
      • 16.1.2 Depositional processes in deep seas
        • Debris-flow deposits
        • Turbidites
        • High- and low-efficiency systems
        • Initiation of mass flows
      • 16.1.3 Composition of deep marine deposits
    • 16.2 SUBMARINE FANS
      • Fig. 16.2 Depositional environments on a submarine fan.
      • 16.2.1 Architectural elements of submarine fan systems
        • Fig. 16.3 The proportions of different architectural elements on submarine fans are determined by the dominant grain size deposited on the fan.
        • Submarine fan channels and levees
          • Fig. 16.4 Thick sandstone beds deposited in a channel in the proximal part of a submarine fan complex.
        • Depositional lobes
          • Fig. 16.5 Schematic graphic sedimentary logs through submarine fan deposits: proximal, mid-fan lobe deposits and lower fan deposits.
        • Turbidite sheets
          • Fig. 16.6 A succession of sandy and muddy turbidite beds deposited on the distal part of a submarine fan complex.
      • 16.2.2 Submarine fan systems
        • Fig. 16.7 Facies model for a gravel-rich submarine fan: typically found in front of coarse fan deltas, the fan is small and consists mainly of debris flows.
        • Gravel-rich systems
        • Sand-rich systems
          • Fig. 16.8 Facies model for a sand-rich submarine fan: sand-rich turbidites form lobes of sediment that build out on the basin floor, with switching of the locus of deposition occurring through time.
        • Mixed sand-mud systems
          • Fig. 16.9 Facies model for a mixed sand-mud submarine fan: the lobes are a mixture of sand and mud and build further out as the turbidites travel longer distances.
        • Muddy systems
          • Fig. 16.10 Facies model for a muddy submarine fan: lobes are very elongate and most of the sand is deposited close to the channels.
      • 16.2.3 Ancient submarine fan systems
    • 16.3 SLOPE APRONS
      • Fig. 16.11 Slope apron deposits include pelagic sediment, slumps, debris flows and sands from the shelf edge. (From Stow 1986.)
    • 16.4 CONTOURITES
      • Fig. 16.12 Schematic graphic sedimentary log through contourite deposits.
    • 16.5 OCEANIC SEDIMENTS
      • 16.5.1 Pelagic sediments
        • Fig. 16.13 Thin-bedded cherts deposited in a deep marine environment.
      • 16.5.2 Distribution of pelagic deposits
        • Fig. 16.14 The distribution of pelagic sediment in the oceans is strongly influenced by the effects of depth-related pressure on the solubility of carbonate minerals. Below the calcite compensation depth particles of the mineral dissolve resulting in concentrations of silica, which is less soluble, and clay minerals.
      • 16.5.3 Hemipelagic deposits
      • 16.5.4 Chemogenic sediments
    • 16.6 FOSSILS IN DEEP OCEAN SEDIMENTS
    • 16.7 RECOGNITION OF DEEP OCEAN DEPOSITS: SUMMARY
      • Characteristics of deep marine deposits
    • FURTHER READING
  • 17 Volcanic Rocks and Sediments
    • 17.1 VOLCANIC ROCKS AND SEDIMENT
      • 17.1.1 Lavas
        • Fig. 17.1 The ropy surface texture of a pahoehoe lava.
      • 17.1.2 Formation of volcaniclastic material
        • Fig. 17.2 Beds of volcaniclastic sediments: the lower layers are coarse lapillistones while the upper beds are finer ash forming tuff beds.
        • Pyroclastic material
        • Autoclastic material
        • Epiclastic material
    • 17.2 TRANSPORT AND DEPOSITION OF VOLCANICLASTIC MATERIAL
      • 17.2.1 Pyroclastic fall deposits
        • Fig. 17.3 Distribution of ash over topography from pyroclastic falls, pyroclastic flows and pyroclastic surges.
      • 17.2.2 Pyroclastic flows
      • 17.2.3 Pyroclastic surges
      • 17.2.4 Pyroclastic flow, surge and fall deposits
        • Fig. 17.4 Sketch graphic sedimentary logs of pyroclastic fall, flow and surge deposits.
      • 17.2.5 Volcanic debris-flow avalanches
      • 17.2.6 Lahars
    • 17.3 ERUPTION STYLES
      • 17.3.1 Plinian eruptions
        • Fig. 17.5 Pelee, Merapi and St Vincent types of pyroclastic flow.
      • 17.3.2 Strombolian (Hawaiian) eruptions
      • 17.3.3 Vulcanian eruptions
        • Fig. 17.6 A small ash cone formed by a pyroclastic eruption.
    • 17.4 FACIES ASSOCIATIONS IN VOLCANIC SUCCESSIONS
      • 17.4.1 Continental basalt provinces
      • 17.4.2 Continental stratovolcanoes
      • 17.4.3 Continental silicic volcanoes
      • 17.4.4 Mid-ocean ridge basalts
      • 17.4.5 Seamounts
      • 17.4.6 Marine stratovolcanoes
      • 17.4.7 Submarine silicic volcanoes
    • 17.5 VOLCANIC MATERIAL IN OTHER ENVIRONMENTS
    • 17.6 VOLCANIC ROCKS IN EARTH HISTORY
      • 17.6.1 Volcanic rocks in stratigraphy
      • 17.6.2 Magnitude of volcanic events
      • 17.6.3 Volcanicity and plate tectonics
    • 17.7 RECOGNITION OF VOLCANIC DEPOSITS: SUMMARY
      • Characteristics of volcaniclastic deposits
    • FURTHER READING
  • 18 Post-depositional Structures and Diagenesis
    • 18.1 POST-DEPOSITIONAL MODIFICATION OF SEDIMENTARY LAYERS
      • 18.1.1 Structures due to sediment instabilities
        • Slumps and slump scars
          • Fig. 18.1 Instabilities within the beds result in parts of the succession slumping to form deformed masses of material: slump scars are the surfaces on which movement occurs.
          • Fig. 18.2 The layers of strata at different angles are a result of slumps rotating the strata.
        • Growth faults
          • Fig. 18.3 Faulting during sedimentation results in the formation of a growth fault: the layers to the right thickening towards the fault are evidence of movement on the fault during deposition.
      • 18.1.2 Structures due to liquefaction
        • Convolute bedding and convolute lamination
          • Fig. 18.4 Convolute lamination and convolute bedding form as a result of local liquefaction of deposits.
          • Fig. 18.5 Convolute lamination in thinly bedded sandstone and mudstone formed as a result of slumping.
        • Overturned cross-stratification
          • Fig. 18.6 Overturned cross-stratification in sandstone beds 60 cm thick: these would have been originally deposited as simple cross-beds by the migration of a subaqueous dune bedform and subsequently the upper part of the cross-bed set was deformed by the shear stress of a flow over the top.
      • 18.1.3 Structures due to fluidisation
        • Dish and pillar structures
          • Fig. 18.7 Movement of fluid up from lower layers results in the formation of dewatering structures.
        • Clastic dykes
        • Sand volcanoes and extruded sheets
          • Fig. 18.8 Movement of fluid up from lower layers incorporates sand that reaches the sediment surface to form a sand volcano.
      • 18.1.4 Structures related to loading
        • Load casts
          • Fig. 18.9 Load casts and ball and pillow structures form where denser sediment, typically sand, is deposited on top of soft mud.
        • Diapirism
          • Fig. 18.10 Diapiric structures form where low-density material such as salt or water-saturated mud is overlain by denser sediments.
    • 18.2 DIAGENETIC PROCESSES
      • Fig. 18.11 Depth and temperature ranges of diagenetic processes.
      • 18.2.1 Burial diagenesis: compaction
        • Fig. 18.12 Changes to the packing of spheres can lead to a reduction in porosity and an overall reduction in volume.
        • Differential compaction
          • Fig. 18.13 Differential compaction between sandstone and mudstone results in draping of layers around a sandstone lens.
          • Fig. 18.14 Compaction of layers within a mudrock around a concretion.
        • Pressure solution/dissolution
          • Fig. 18.15 Pressure solution has occurred at the contact between two limestone pebbles.
        • Compaction effects
          • Fig. 18.16 Types of grain contact: there is generally a progressive amount of compaction from point, to long contacts (involving a re-orientation of grains), to concavo-convex and to sutured contacts (which both involve a degree of pressure dissolution.
      • 18.2.2 Chemical processes of diagenesis: cementation
        • Dissolution
        • Precipitation of cements
          • Fig. 18.17 Cement fabrics: (a) overgrowths formed by precipitation of the same mineraI (such as quartz or calcite) are in optical continuity with the grain; (b) a poikilotopic fabric is the result of cement minerals completely enveloping grains; (c) an isopachous cement grows on all surfaces within pores, a pattern commonly seen in sparry calcite cements; (d) a meniscus fabric forms when cement precipitation occurs from water fIowing down through the sediment.
        • Recrystallisation
        • Replacement
      • 18.2.3 Nodules and concretions
        • Septarian concretions
        • Flints and other secondary cherts
      • 18.2.4 Colour changes during diagenesis
    • 18.3 CLASTIC DIAGENESIS
      • Fig. 18.18 An isopachous, sparry calcite cement formed in the pore spaces between pebbles lines the surfaces of the pebbles.
      • 18.3.1 Diagenesis and sandstone petrography
        • Silica cement
        • Carbonate cement
        • Clay mineral cements
        • Compaction effects
      • 18.3.2 Clay mineral diagenesis
      • 18.3.3 Diagenesis of organic matter in marine muds
        • Fig. 18.19 Flow-chart of the pathways of diagenesis of organic matter in sediments.
    • 18.4 CARBONATE DIAGENESIS
      • 18.4.1 Compaction effects in limestones: stylolites and bedding planes
        • Fig. 18.20 Stylolites are surfaces of pressure dissolution, in this case marked by an irregular band of insoluble residue in a limestone.
      • 18.4.2 Dolomitisation
        • Fig. 18.21 Four of the models proposed for the processes of dolomitisation. (From Tucker & Wright 1990.)
      • 18.4.3 Diagenesis and carbonate petrography
        • Neomorphism
        • Carbonate cements
        • Dolomite
    • 18.5 POST-DEPOSITIONAL CHANGES TO EVAPORITES
      • Fig. 18.22 Dissolution of evaporite minerals within a stratigraphic succession results in the formation of a breccia due to collapse of the beds.
    • 18.6 DIAGENESIS OF VOLCANICLASTIC SEDIMENTS
    • 18.7 FORMATION OF COAL, OIL AND GAS
      • 18.7.1 Coal-forming environments
        • Fig. 18.23 Peat-forming environments: waterlogged areas where organic material can accumulate may either be regions of stagnant water (ombotrophic mires or bogs) or places where there is a through-flow of fresh or saline water (rheotrophic mires or marshes).
      • 18.7.2 Formation of coal from peat
        • Fig. 18.24 The formation of coal from peat involves a considerable amount of compaction, initially converting peat into brown coal (lignite) before forming bituminous coal.
      • 18.7.3 Formation of oil and gas
        • Fig. 18.25 With increased burial the maturation of kerogen results in the formation initially of oil and later gas: greater heating results in the complete breakdown of the hydrocarbons.
      • 18.7.4 Oil and gas reservoirs
        • Hydrocarbon traps
          • Fig. 18.26 Cartoon of the relationships between the source rock, migration pathway, reservoir, trap and cap rocks required for the accumulation of oil and gas in the subsurface.
        • Reservoir rocks
        • Economic oil and gas accumulations
    • FURTHER READING
  • 19 Stratigraphy: Concepts and Lithostratigraphy
    • 19.1 GEOLOGICAL TIME
      • 19.1.1 Geological time units
        • Fig. 19.1 Nomenclature used for geochronological and chronostratigraphic units.
        • Eons
        • Eras
        • Periods/Systems
        • Epochs/Series
        • Ages/Stages
      • 19.1.2 Stratigraphic charts
        • Fig. 19.2 A stratigraphic chart with the ages of the different divisions of geological time. (Data from Gradstein et al. 2004.)
      • 19.1.3 Golden spikes
    • 19.2 STRATIGRAPHIC UNITS
    • 19.3 LITHOSTRATIGRAPHY
      • 19.3.1 Stratigraphic relationships
        • Superposition
          • Fig. 19.3 Principles of superposition: (a) a ‘layer-cake’ stratigraphy; (b) stratigraphic relations around a reef or similar feature with a depositional topography.
        • Unconformities
          • Fig. 19.4 Gaps in the record are represented by unconformities: (a) angular unconformities occur when older rocks have been deformed and eroded prior to later deposition above the unconformity surface; (b) disconformities represent breaks in sedimentation that may be associated with erosion but without deformation.
          • Fig. 19.5 An angular unconformity between horizontal sandstone beds above and steeply dipping shaly beds below.
        • Cross-cutting relationships
          • Fig. 19.6 Stratigraphic relationships can be simple indicators of the relative ages of rocks: (a) cross-cutting relations show that the igneous features are younger than the sedimentary strata around them; (b) a fragment of an older rock in younger strata provides evidence of relative ages, even if they are some distance apart.
        • Included fragments
        • Way-up indicators in sedimentary rocks
          • Fig. 19.7 Way-up indicators in sedimentary rocks.
      • 19.3.2 Lithostratigraphic units
      • 19.3.3 Description of lithostratigraphic units
        • Lithology and characteristics
        • Definition of top and base
        • Type section
        • Thickness and extent
        • Other information
      • 19.3.4 Lithostratigraphic nomenclature
      • 19.3.5 Lithodemic units: non-stratiform rock units
    • 19.4 APPLICATIONS OF LITHOSTRATIGRAPHY
      • 19.4.1 Lithostratigraphy and geological maps
      • 19.4.2 Lithostratigraphy and environments
        • Fig. 19.8 Relationships between the boundaries of lithostratigraphic units (defined by lithological characteristics resulting from the depositional environment) and time-lines in a succession of strata formed during gradual sea-level rise (transgression).
      • 19.4.3 Lithostratigraphy and correlation
      • 19.4.4 Lithostratigraphy and time: gaps in the record
    • FURTHER READING
  • 20 Biostratigraphy
    • 20.1 FOSSILS AND STRATIGRAPHY
    • 20.2 CLASSIFICATION OF ORGANISMS
      • 20.2.1 Species
        • Fig. 20.1 The Linnaean hierarchical system for the taxonomy of organisms.
      • 20.2.2 Other ranks in taxonomy
        • Fig. 20.2 Major groups of organisms preserved as macrofossils in the stratigraphic record and their age ranges.
    • 20.3 EVOLUTIONARY TRENDS
      • 20.3.1 Population fragmentation and phyletic transformation
      • 20.3.2 Phyletic gradualism and punctuated equilibrium
      • 20.3.3 Speciation and biostratigraphy
    • 20.4 BIOZONES AND ZONE FOSSILS
      • Fig. 20.3 Zonation schemes used in biostratigraphic correlation. (Adapted from North American Commission on Stratigraphic Nomenclature 1983.)
      • Interval biozones
      • Assemblage biozones
      • Acme biozones
      • 20.4.1 Rate of speciation
      • 20.4.2 Depositional environment controls
      • 20.4.3 Mobility of organisms
      • 20.4.4 Geographical distribution of organisms
      • 20.4.5 Abundance and size of fossils
      • 20.4.6 Preservation potential
    • 20.5 TAXA USED IN BIOSTRATIGRAPHY
      • 20.5.1 Marine macrofossils
        • Fig. 20.4 Shelly fossils in a limestone bed.
        • Trilobites
        • Graptolites
        • Brachiopods
        • Ammonoids
        • Gastropods
        • Echinoderms
        • Corals
      • 20.5.2 Marine microfossils
        • Foraminifera
        • Radiolaria
        • Calcareous nanofossils
        • Other microfossils
      • 20.5.3 Terrestrial fossil groups used in biostratigraphy
    • 20.6 BIOSTRATIGRAPHIC CORRELATION
      • 20.6.1 Correlating different environments
      • 20.6.2 Graphical correlation schemes
        • Fig. 20.5 Graphical correlation methods are used to identify changes in rates of sedimentation or a hiatus in deposition. (Adapted from Shaw 1964.)
    • 20.7 BIOSTRATIGRAPHY IN RELATION TO OTHER STRATIGRAPHIC TECHNIQUES
    • FURTHER READING
  • 21 Dating and Correlation Techniques
    • 21.1 DATING AND CORRELATION TECHNIQUES
    • 21.2 RADIOMETRIC DATING
      • 21.2.1 Radioactive decay series
        • Fig. 21.1 Radioactive decay results in the formation of a new ‘daughter’ isotope from the ‘parent’ isotope.
      • 21.2.2 Practical radiometric dating
      • 21.2.2 Potassium–argon and argon–argon dating
        • Fig. 21.2 The main decay series used in radiometric dating of rocks: the K–Ar, Rb–Sr and U–Pb systems are the ones most commonly used –14C dating is mainly used for dating archaeological materials.
      • 21.2.3 Other radiometric dating systems
        • Rubidium–strontium dating
        • Uranium–lead dating
        • Samarium–neodymium dating
        • Rhenium–osmium dating
      • 21.2.4 Applications of radiometric dating
    • 21.3 OTHER ISOTOPIC AND CHEMICAL TECHNIQUES
      • 21.3.1 Strontium isotopes
        • Fig. 21.3 The strontium isotope curve: these changes in the ratio of the isotopes 86Sr and 87Sr through geological time can be used to determine the age of some rocks, but the same ratio can occur at different ages. (Data from Faure 1986.)
      • 21.3.2 Thermochronological techniques
      • 21.3.3 Chemostratigraphy
    • 21.4 MAGNETOSTRATIGRAPHY
      • Fig. 21.4 Reversals in the polarity of the Earth’s magnetic field through part of the Cenozoic. (From Haq et al. 1988.)
      • 21.4.1 The magnetic record in rocks
      • 21.4.2 Practical magnetostratigraphy
      • 21.4.3 Magnetostratigraphic correlation
        • Fig. 21.5 An illustration of how different successions can be correlated using a combination of magnetic reversals, marker beds and biostratigraphic data.
    • 21.5 DATING IN THE QUATERNARY
      • 21.5.1 Carbon-14 dating
      • 21.5.2 Uranium-series dating
      • 21.5.3 Oxygen isotope stratigraphy
      • 21.5.4 Luminescence and electron spin resonance dating
      • 21.5.5 Cosmogenic isotopes
      • 21.5.6 Amino-acid racemisation
      • 21.5.7 Annual cycles in nature
    • FURTHER READING
  • 22 Subsurface Stratigraphy and Sedimentology
    • 22.1 INTRODUCTION TO SUBSURFACE STRATIGRAPHY AND SEDIMENTOLOGY
    • 22.2 SEISMIC REFLECTION DATA
      • 22.2.1 Acquisition of seismic reflection data
        • Fig. 22.1 In marine seismic reflection surveys the ship tows the energy source, the airgun, and the receivers either as a single line or in multiple lines to generate a 3-D survey.
      • 22.2.2 Processing of seismic reflection data
        • Fig. 22.2 Example of a seismic reflection profile: the horizontal scale is distance (in this case several kilometres across), but the vertical scale is in two-way travel time, that is, the time it takes for sound waves to reach a subsurface reflector and return to the surface. If the acoustic properties of the rock are known (these vary with the bulk density) this can be converted to depth.
      • 22.2.3 Visualisation of seismic reflection data
      • 22.2.4 Interpretation of seismic reflection data
      • 22.2.5 Stratigraphic relationships on seismic profiles
        • Fig. 22.3 Reflector patterns and reflector relationships on seismic reflection profiles.
        • Continuous reflectors
        • Clinoforms
        • Unconformities
        • Erosional truncation
        • Onlap
        • Downlap
        • Toplap
        • Offlap
      • 22.2.6 Structural features on seismic reflection profiles
      • 22.2.7 Seismic facies
      • 22.2.8 Interpretation of three-dimensional data
    • 22.3 BOREHOLE STRATIGRAPHY AND SEDIMENTOLOGY
      • 22.3.1 Borehole cuttings
      • 22.3.2 Core
        • Fig. 22.4 Cores cut by a drill bit and brought to the surface provide information about subsurface strata.
      • 22.2.3 Core logging
    • 22.4 GEOPHYSICAL LOGGING
      • Fig. 22.5 Geophysical instruments are normally mounted on a sonde that passes through formations on the end of a wireline.
      • Fig. 22.6 (a) Determination of lithology using information provided by a gamma-ray logging tool. (b) Determination of lithology and porosity using information provided by a sonic logging tool. (From Rider 2002.)
      • 22.4.1 Petrophysical logging tools
        • Caliper log
          • Fig. 22.7 Wireline logging traces produced by geophysical logging tools.
        • Gamma-ray log
        • Resistivity logs
        • Sonic log
        • Density logs
        • Neutron logs
        • Electromagnetic propagation log
        • Nuclear magnetic resonance logs
      • 22.4.2 Geological logging tools
        • Dipmeter log
        • Microimaging tools
        • Ultrasonic imaging logs
      • 22.4.3 Sedimentological interpretation of wireline logs
        • Fig. 22.8 Trends in gamma-ray traces can be interpreted in terms of depositional environment provided that there is sufficient corroborative evidence from cuttings and cores. (From Cant 1992.)
    • 22.5 SUBSURFACE FACIES AND BASIN ANALYSIS
    • FURTHER READING
  • 23 Sequence Stratigraphy and Sea-level Changes
    • 23.1 SEA-LEVEL CHANGES AND SEDIMENTATION
      • 23.1.1 Changes to a shoreline
        • Fig. 23.1 Relative sea-level change (the change in water depth at a point) may be due to uplift or subsidence of the crust, increase or decrease in the amount of water, or addition of sediment to the sea floor. It is often not possible to determine which mechanism is responsible if there is information from only one place.
      • 23.1.2 Sea level and sedimentation
      • 23.1.3 Transgression, regression and forced regression
        • Fig. 23.2 (a) If sea level rises faster than sediment is supplied the coastline shifts landward: this is known as transgression and the pattern in the sediments is retrogradational. (b) If sediment is supplied to a coast where there is no (or relatively slow) sea-level rise the coastline moves seaward: this is regression and the sediment pattern is progradational. (c) Sea-level fall results in a forced regression and the sediment pattern is retogradational, and may include erosion surfaces. (d) A situation where the coastline stays in the same position for long periods of time is relatively unusual and requires a balance between relative sea-level rise and sediment supply producing a pattern of aggradation in the sediments.
      • 23.1.4 The concept of accommodation
      • 23.1.5 Rates of sea-level change and sediment supply
        • Fig. 23.3 The various possible patterns of sedimentation that can result from different relative amounts of sediment supply and relative sea-level change are summarised in this diagram. The responses to the different combinations are expressed in terms of vertical sedimentary successions, as seen in successions of strata in outcrop or boreholes, or as geometries seen in regional cross-sections or seismic reflection profiles expressed in terms of shoreline trajectories. Eight main scenarios (I—VIII) are recognised.
        • Shoreline trajectory
        • Depositional slope, onshore and offshore
      • 23.1.6 Progradation, aggradation and retrogradation
      • 23.1.7 Cycles of sea-level change
        • Fig. 23.4 A sinusoidal curve of sea-level variation combined with a long-term increase in relative sea-level results in periods when there is relative sea-level rise (and hence transgression) and periods of relative sea-level fall (resulting in regression).
    • 23.2 DEPOSITIONAL SEQUENCES AND SYSTEMS TRACTS
      • Fig. 23.5 Two main types of continental margin are recognised, each resulting in different stratigraphic patterns when there are sea-level fluctuations: (a) shelf-break margins have a shallow shelf area bordered by a steeper slope down to the deeper basin floor; (b) ramp margins do not have a distinct change in slope at a shelf edge.
      • 23.2.1 Shelf-break margin depositional sequence (Fig. 23.6)
        • Highstand
          • Fig. 23.6 Variations in sea level that follow the pattern in Fig. 23.4 affecting a shelf-break margin result in a series of systems tracts formed at different stages: the lowstand is characterised by deep-basin turbidites if the sea level falls to the shelf edge.
        • Sequence boundary
        • Lowstand
        • Transgressive surface
        • Transgressive systems tract
        • Maximum flooding surface
        • Highstand
      • 23.2.2 Ramp margin depositional sequence (Fig. 23.7)
        • Highstand
          • Fig. 23.7 Variations in sea level that follow the pattern in Fig. 23.4 affecting a ramp margin result in a series of systems tracts formed at different stages: during lowstand the deposition is shifted down the ramp.
        • Sequence boundary
        • Falling stage systems tract
        • Lowstand
        • Transgressive surface, transgressive systems tract, maximum flooding surface, highstand
    • 23.3 PARASEQUENCES: COMPONENTS OF SYSTEMS TRACTS
      • 23.3.1 Parasequences
        • Fig. 23.8 A higher frequency sea-level fluctuation curve superimposed on the curve in Fig. 23.4 produces a pattern of short-term rises and falls in sea level within the general trends of transgression and regression. These short-term fluctuations result in creation of small amounts of accommodation being created, even during the falling stage.
        • Parasequence boundaries
        • Parasequence thickness
          • Fig. 23.9 A schematic graphic sedimentary log of a parasequence in an inner shelf shallow-marine setting.
          • Fig. 23.10 A schematic graphic sedimentary log of a parasequence in an offshore shelf shallow-marine setting.
        • Parasequence sets
        • Parasequence sets and systems tracts
          • Fig. 23.11 The stacking patterns of parasequences to form parasequence sets are characteristic of different systems tracts.
          • Fig. 23.12 A falling-stage systems tract (FSST) on a ramp margin can show different patterns of deposition: if the sea level falls relatively slowly with respect to sediment supply deposition forms a continuous succession across the ramp as an attached FSST; relatively fast sea-level fall results in a detached FSST.
      • 23.3.2 Sequences and parasequences: scales and variations
    • 23.4 CARBONATE SEQUENCE STRATIGRAPHY
      • Fig. 23.13 The responses of a carbonate rimmed shelf to changes in sea level. An important difference with clastic systems tracts is that the carbonate productivity varies because most carbonate material is biogenic and forms in shallow water. During high-stand and transgressive systems tracts wide areas of shallow water allow more sediment to be formed, whereas at falling stage and lowstand production of carbonate sediment is much lower.
    • 23.5 SEQUENCE STRATIGRAPHY IN NON-MARINE BASINS
    • 23.6 ALTERNATIVE SCHEMES IN SEQUENCE STRATIGRAPHY
    • 23.7 APPLICATIONS OF SEQUENCE STRATIGRAPHY
      • Fig. 23.14 A summary of the stratal geometries and the patterns within systems tracts in a depositional sequence.
      • 23.7.1 Sequence stratigraphic analysis of seismic sections
      • 23.7.2 Sequence stratigraphic analysis of graphic sedimentary logs
        • Fig. 23.15 Schematic sedimentary log through an idealised depositional sequence: in practice, the succession seen in outcrop or in the subsurface will often include only parts of this whole pattern, with considerable variations in thicknesses of the systems tracts. (a) Lower part of the succession. (b) Continuation into the upper part of the succession.
      • 23.7.3 Sequence stratigraphic analysis of geophysical logs
        • Fig. 23.16 Interpretation of gamma-ray logs in terms of parasequences and systems tracts.
      • 23.7.4 Correlation of sections using sequence stratigraphic principles
        • Fig. 23.17 A hypothetical example of correlation between logs in different parts of the coastal and marine environments using sequence stratigraphic principles. Note that correlation is on the basis that in different places on the shelf and in the basin there will be different facies deposited at the same time.
    • 23.8 CAUSES OF SEA-LEVEL FLUCTUATIONS
      • 23.8.1 Local changes in sea level
        • Fig. 23.18 There are a number of possible causes of sea-level change related to tectonic and climatic factors; the approximate magnitudes of change and the rates at which it will occur are indicated in each case.
      • 23.8.2 Glacio-eustasy
      • 23.8.3 Thermo-tectonic causes of sea-level change
      • 23.8.4 Other causes of global sea-level change
      • 23.8.5 Cyclicity in changes in sea level
        • Fig. 23.19 First-, second- and third-order sea-level cycles are considered to be global signatures due to tectonic and climatic controls outlined in Fig. 23.18. (Modified from Vail et al. 1977.)
        • First-order cycles
        • Second-order cycles
        • Third-order cycles
      • 23.8.6 Short-term changes in sea level
        • Fig. 23.20 Milankovitch cycles: the eccentricity of the Earth’s orbit of the Sun, changes on the obliquity of the axis of rotation of the Earth and the precession of the axis of rotation may result in global climatic cycles on the scale of tens of thousands of years.
      • 23.8.7 Global synchroneity of sea-level fluctuations
    • 23.9 SEQUENCE STRATIGRAPHY: SUMMARY
    • FURTHER READING
  • 24 Sedimentary Basins
    • 24.1 CONTROLS ON SEDIMENT ACCUMULATION
      • 24.1.1 Tectonics of sedimentary basins
      • 24.1.2 Climate, sediment supply and base-level controls
        • Fig. 24.1 The facies of deposits in sedimentary basins and their distributions in three dimensions are controlled by climatic and tectonic factors, the nature of the hinterland bedrock and the connection with the oceans.
        • Connection to oceans and sea-level changes
        • Climatic effects of weathering, transport and deposition
        • Bedrock and topography controls on sediment supply
      • 24.1.3 Tectonic setting classification of sedimentary basins
    • 24.2 BASINS RELATED TO LITHOSPHERIC EXTENSION
      • 24.2.1 Rift basins (Fig. 24.2)
        • Fig. 24.2 Rift basins form by extension in continental crust: sediment is supplied from the rift flanks or may also be brought in by rivers flowing along the axis of the rift.
        • Fig. 24.3 Rift valleys are characterised by steep sides formed by the extensional faults that form the basin (East African Rift Valley).
      • 24.2.2 Intracratonic basins (Fig. 24.4)
        • Fig. 24.4 Intracratonic basins are broad regions of subsidence within continental crust: they are typically broad and shallow basins.
      • 24.2.3 Proto-oceanic troughs: the transition from rift to ocean (Fig. 24.5)
        • Fig. 24.5 With continued extension in a rift, the lithosphere thins and oceanic crust starts to form in a proto-oceanic trough where sedimentation occurs in a marine setting.
      • 24.2.4 Passive margins (Fig. 24.6)
        • Fig. 24.6 An ocean basin is flanked by thinned continental crust, which subsides to form passive margins to the ocean basin.
      • 24.2.5 Ocean basins (Fig. 24.6)
      • 24.2.6 Obducted slabs
    • 24.3 BASINS RELATED TO SUBDUCTION
      • Fig. 24.7 An arc-trench system forms where oceanic crust is subducted at an ocean trench and the downgoing plate releases magma at depth, which rises to form a volcanic arc. Sediment may accumulate in the trench, in the forearc basin between the trench and the arc and in the region behind the arc called a backarc basin if there is subsidence due to extension (see also retroarc basins, Fig. 24.13).
      • Fig. 24.8 Arc-trench systems include chains of volcanoes that form the arc.
      • 24.3.1 Trenches (Fig. 24.9)
        • Fig. 24.9 Forearc basins, trenches and extensional backarc basins are supplied by volcaniclastic material from the adjacent arc and may also receive continentally derived detritus if the overriding plate is continental crust.
      • 24.3.2 Accretionary complexes
        • Fig. 24.10 Sediment deposited in an ocean trench includes both material derived from the overriding plate and pelagic material. As subduction proceeds sediment is scraped off the downgoing plate to form an accretionary prism of deformed sedimentary material.
      • 24.3.3 Forearc basins (Fig. 24.9)
      • 24.3.4 Backarc basins (Fig. 24.9)
    • 24.4 BASINS RELATED TO CRUSTAL LOADING
      • Fig. 24.11 The major mountainous areas of the world occur in areas of plate collision where an orogenic belt forms.
      • 24.4.1 Peripheral foreland basins (Fig. 24.12)
        • Fig. 24.12 Collision between two continental plates results in the formation of an orogenic belt where there is thickening of the crust: this results in an additional load being placed on the crust either side and causes a downward flexure of the crust to form peripheral foreland basins.
      • 24.4.2 Retroarc foreland basins (Fig. 24.13)
        • Fig. 24.13 The thickness of the crust increases due to emplacement of magma in a volcanic arc at a continental margin, resulting in flexure of the crust behind the arc to form a retroarc foreland basin.
    • 24.5 BASINS RELATED TO STRIKE-SLIP TECTONICS
      • 24.5.1 Strike-slip basins (Fig. 24.14)
        • Fig. 24.14 Basins may form by a variety of mechanisms in strike-slip settings: (a) a releasing bend, (b) a fault termination, (c) a fault offset (usually referred to as a pull-apart basin) and (d) at a junction between faults. Note that if the relative motion of the faults were reversed in each case the result would be uplift instead of subsidence.
    • 24.6 COMPLEX AND HYBRID BASINS
    • 24.7 THE RECORD OF TECTONICS IN STRATIGRAPHY
      • Fig. 24.15 The Wilson Cycle of extension to form a rift basin and ocean basin followed by basin closure and formation of an orogenic belt. (Adapted from Wilson 1966.)
    • 24.8 SEDIMENTARY BASIN ANALYSIS
      • Fig. 24.16 Basin analysis techniques.
      • 24.8.1 Structural analysis
      • 24.8.2 Geophysical data
      • 24.8.3 Thermal history
      • 24.8.4 Stratigraphic analysis
      • 24.8.5 Sedimentological analysis
      • 24.8.6 Geohistory analysis
    • 24.9 THE SEDIMENTARY RECORD
    • FURTHER READING
  • Back Matter
    • References
    • Index

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Vörumerki: John Wiley
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Sedimentology and Stratigraphy

Vörumerki: John Wiley
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