Contents

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Contents

• Introduction
• Sedimentology concepts
• Fluvial environments
• Deltaic environments
• Coastal environments
• Offshore marine environments

• Sea-level change
• Sequence stratigraphy concepts
• Marine sequence stratigraphy
• Nonmarine sequence stratigraphy
• Basin and reservoir modeling
• Reflection

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Fluvial environments

• Channel patterns (fluvial styles) of alluvial
  rivers are commonly classified as
• Braided rivers
• Meandering rivers
• Straight rivers
• Anastomosing rivers
• Fluvial style is primarily controlled by specific
  stream power (W m-2) and bed-load grain size, but
  also by bank stability and the amount of bed load
  (but not the proportion of suspended load!)
• ?fluid density Qdischarge sslope (gradient)
  wchannel width

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Animation
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Fluvial environments

• Channel patterns (fluvial styles) of alluvial
  rivers are commonly classified as
• Braided rivers
• Meandering rivers
• Straight rivers
• Anastomosing rivers
• Fluvial style is primarily controlled by specific
  stream power (W m-2) and bed-load grain size, but
  also by bank stability and the amount of bed load
  (but not the proportion of suspended load!)
• ?fluid density Qdischarge sslope (gradient)
  wchannel width

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Fluvial environments

• Bars are sandy or gravelly macroforms in channels
  that are emergent, mostly unvegetated features at
  low flow stage, and undergo submergence and rapid
  modification during high discharge
• Point bars form on inner banks and typically
  accrete laterally, commonly resulting in
  lateral-accretion surfaces mid-channel or braid
  bars accrete both laterally and downstream
• Bars are always associated with channels a
  genetically related bar/bar complex and
  channel/channel complex is known as a storey

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Fluvial environments

• Bars are sandy or gravelly macroforms in channels
  that are emergent, mostly unvegetated features at
  low flow stage, and undergo submergence and rapid
  modification during high discharge
• Point bars form on inner banks and typically
  accrete laterally, commonly resulting in
  lateral-accretion surfaces mid-channel or braid
  bars accrete both laterally and downstream
• Bars are always associated with channels a
  genetically related bar/bar complex and
  channel/channel complex is known as a storey

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Fluvial environments

• Lateral accretion involves higher-order bounding
  surfaces dipping perpendicular to paleoflow
  direction and associated lower-order bounding
  surfaces in the case of downstream accretion
  higher-order bounding surfaces dip parallel to
  paleoflow direction
• Braided rivers are characterized by a dominance
  of braid bars exhibiting both lateral and
  downstream accretion meandering rivers primarily
  contain point bars with lateral accretion in
  straight (and most anastomosing) rivers bars are
  commonly almost absent

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Animation
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Fluvial environments

• Lateral accretion involves higher-order bounding
  surfaces dipping perpendicular to paleoflow
  direction and associated lower-order bounding
  surfaces in the case of downstream accretion
  higher-order bounding surfaces dip parallel to
  paleoflow direction
• Braided rivers are characterized by a dominance
  of braid bars exhibiting both lateral and
  downstream accretion meandering rivers primarily
  contain point bars with lateral accretion in
  straight (and most anastomosing) rivers bars are
  commonly almost absent

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Fluvial environments

• Facies successions in sandy to gravelly channel
  deposits typically fine upward, from a coarse
  channel lag, through large-scale to small-scale
  cross stratified sets (commonly with decreasing
  set height), and finally overlain by muddy
  overbank deposits
• Facies successions produced by different fluvial
  styles can be extremely similar!
• The geometry and three-dimensional arrangement of
  architectural elements therefore provides a much
  better means of inferring fluvial styles from the
  sedimentary record

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Fluvial environments

• Facies successions in sandy to gravelly channel
  deposits typically fine upward, from a coarse
  channel lag, through large-scale to small-scale
  cross stratified sets (commonly with decreasing
  set height), and finally overlain by muddy
  overbank deposits
• Facies successions produced by different fluvial
  styles can be extremely similar!
• The geometry and three-dimensional arrangement of
  architectural elements therefore provides a much
  better means of inferring fluvial styles from the
  sedimentary record

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Fluvial environments

• Channel belts consist of channel-bar and
  channel-fill deposits the proportion of the two
  generally decreases markedly from braided rivers
  to anastomosing rivers
• The geometry of a channel belt (width/thickness
  ratio) is a function of the channel width and the
  degree of lateral migration values are typically
  much higher for braided systems (gtgt100) than for
  straight or anastomosing systems (lt25)
• Sheets have width/thickness ratios of gt50
• Ribbons have width/thickness ratios of lt15
• Residual-channel deposits are predominantly muddy
  (occasionally organic) deposits that accumulate
  in an abandoned channel where flow velocities are
  extremely small

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Fluvial environments

• Channel belts consist of channel-bar and
  channel-fill deposits the proportion of the two
  generally decreases markedly from braided rivers
  to anastomosing rivers
• The geometry of a channel belt (width/thickness
  ratio) is a function of the channel width and the
  degree of lateral migration values are typically
  much higher for braided systems (gtgt100) than for
  straight or anastomosing systems (lt25)
• Sheets have width/thickness ratios of gt50
• Ribbons have width/thickness ratios of lt15
• Residual-channel deposits are predominantly muddy
  (occasionally organic) deposits that accumulate
  in an abandoned channel where flow velocities are
  extremely small

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Fluvial environments

• Overbank environments are dominated by
  fine-grained facies (predominantly muds)
• Natural-levee deposits are wedges (wings) of
  sediment that form adjacent to the channel,
  dominated by fine sand and silt exhibiting planar
  stratification or (climbing) ripple cross
  stratification
• Crevasse-splay deposits are usually cones of
  sandy to silty facies with both coarsening-upward
  and fining-upward successions, and are formed by
  small, secondary channels during peak flow
• Flood-basin deposits are the most distal facies,
  consisting entirely of muddy sediments deposited
  from suspension, and are volumetrically very
  important (mainly in low-energy fluvial settings)

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Fluvial environments

• Paleosols (well drained conditions) and
  occasional peats (poorly drained conditions)
  occur frequently in overbank environments and are
  important indicators of variations of clastic
  aggradation rates and the position relative to
  active channels (proximal vs. distal)
• The pedofacies concept refers to the maturity of
  a paleosol, irrespective of the specific set of
  pedogenic processes operating, in the case of
  floodplains mainly controlled by distance to the
  active channel
• Lacustrine deposits can be important in overbank
  environments characterized by high water tables,
  and are also found in distal settings they are
  more likely to contain primary sedimentary
  structures (horizontal lamination) than their
  frequently bioturbated subaerial counterparts

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Fluvial environments

• Paleosols (well drained conditions) and
  occasional peats (poorly drained conditions)
  occur frequently in overbank environments and are
  important indicators of variations of clastic
  aggradation rates and the position relative to
  active channels (proximal vs. distal)
• The pedofacies concept refers to the maturity of
  a paleosol, irrespective of the specific set of
  pedogenic processes operating, in the case of
  floodplains mainly controlled by distance to the
  active channel
• Lacustrine deposits can be important in overbank
  environments characterized by high water tables,
  and are also found in distal settings they are
  more likely to contain primary sedimentary
  structures (horizontal lamination) than their
  frequently bioturbated subaerial counterparts

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Fluvial environments

• Facies models highlight conspicuous differences
  between different fluvial styles
• Channel-belt width/thickness ratio (braided
  high meandering intermediate
  straight/anastomosing low)
• Channel-deposit proportion (braided high
  meandering intermediate straight/anastomosing
  low)
• Overbank-deposit proportion (braided low
  meandering intermediate straight/anastomosing
  high)
• Overbank-deposit geometry (meandering
  wedge-shaped straight/anastomosing highly
  irregular due to numerous crevasse channels)
• Overbank facies (meandering well-drained
  paleosols common straight/anastomosing peats
  and lacustrine deposits common)

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Fluvial environments

• Avulsion is the sudden diversion of a channel to
  a new location on the floodplain, leading to the
  abandonment of a channel belt and the initiation
  of a new one
• Avulsions are the inevitable consequence of the
  increase of cross-valley slope (typically through
  a crevasse channel) relative to down-valley slope
  along the channel, associated with the growth of
  an alluvial ridge
• An avulsion belt constitutes an extensive network
  of rapidly aggrading, narrow, crevasse-like
  channels with genetically associated overbank
  deposits, that may surround the new channel belt

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Fluvial environments

• Alluvial architecture refers to the
  three-dimensional arrangement of channel-belt
  deposits and overbank deposits in a fluvial
  succession
• The nature of alluvial architecture (e.g., the
  proportion of channel-belt to overbank deposits)
  is dependent on fluvial style, aggradation rate,
  and the frequency of avulsion
• When alluvial architecture is dominated by
  channel-belt deposits, the separation of channel
  belts from storeys can be extremely difficult

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Fluvial environments

• Alluvial architecture refers to the
  three-dimensional arrangement of channel-belt
  deposits and overbank deposits in a fluvial
  succession
• The nature of alluvial architecture (e.g., the
  proportion of channel-belt to overbank deposits)
  is dependent on fluvial style, aggradation rate,
  and the frequency of avulsion
• When alluvial architecture is dominated by
  channel-belt deposits, the separation of channel
  belts from storeys can be extremely difficult

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Fluvial environments

• Alluvial architecture refers to the
  three-dimensional arrangement of channel-belt
  deposits and overbank deposits in a fluvial
  succession
• The nature of alluvial architecture (e.g., the
  proportion of channel-belt to overbank deposits)
  is dependent on fluvial style, aggradation rate,
  and the frequency of avulsion
• When alluvial architecture is dominated by
  channel-belt deposits, the separation of channel
  belts from storeys can be extremely difficult