Clastic Hierarchies

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Clastic Hierarchies and Eustasy Spring 2005
Professor Christopher G. St. C.
Kendall kendall_at_sc.edu 777.2410
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Clastic Depositional Systems

• Their Response
• to
• Base Level Change

Based, in part, on classroom lectures by David
Barbeau Chris Kendall
3
Lecture Series Overview

• Sequence stratigraphy stratigraphic surfaces
• Basics Ideal sequence of Vail et al 1977
  associated terminology
• Clastic system response to changing sea level and
  rates of sedimentation - with movie
• Carbonate systems response to changing sea level
  and rates of sedimentation - with movie
• Exercises Sequence stratigraphy of carbonates
  and clastics from chronostratigraphy, seismic,
  outcrop and well log character

4
Sedimentary rocks are the product of the
generation, transport, deposition, and diagenesis
of detritus and solutes derived from pre-existing
rocks.
5
Sedimentary rocks are the product of the
creation, transport, deposition, and diagenesis
of detritus and solutes derived from pre-existing
rocks.
6
After Press Siever, 98
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Depositional Systems

• depositional system assemblage of multiple
  process-related sedimentary facies assemblages,
  commonly identified by the geography in which
  deposition occurs.
• EX nearshore depositional system, deep marine
  depositional system, glacial depositional system,
  fluvial depositional system
• NB depositional systems are
• modern features
• used to interpret ancient sedimentary successions

8
Types of Depositional Systems

• marine ? ocean, sea
• transitional ? part land, part ocean
• terrestrial ? land

9
Clastic Depositional Systems
Terrestrial
Transitional
Marine
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Clastic Depositional Systems
Terrestrial
Transitional
Marine
11
Clastic Depositional Systems
Terrestrial
Transitional
Marine
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Characteristics of Clastic System

• Critical stratigraphic signals of system?
• Geomorphologic tectonic setting
• Dominant sedimentary processes
• Facies
• Subdividing surfaces
• Lithology
• Sedimentary structures
• Geometries Confined versus open
• Fauna flora

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Types of Depositional Systems

• marine ? ocean, sea
• terrestrial ? land
• transitional ? part land, part ocean

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Types of Depositional Systems

• marine ? ocean, sea
• transitional ? part land, part ocean
• terrestrial ? land

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Marine Depositional Systems

• shallow/nearshore
• tide-dominated
• wave-dominated
• reef
• shelf/platform
• carbonate
• clastic
• deep marine
• deep sea fans
• pelagic

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Marine Depositional Systems

• wave-dominated coasts
• tide-dominated coasts
• fluvial-dominated coasts (deltas)
• carbonate reefs
• clastic shelves platforms
• carbonate shelves platforms
• deepwater fans
• pelagic abyssal plains

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Coastal Depositional Systems

• Form proximal to shorelines
• Geographically narrow, geologically important
• Fluid flow transport and deposition
• Surface waves
• Tidal waves (not tsunami!)
• Fluvial input
• Grain-size decreases with deeper water
• Onshore, offshore longshore sediment transport
  important
• Net sediment input (often from rivers) often
  leads to progradational geometries
• Important for tracking sea-level changes

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Coast Types
Dalrymple et al, 1992
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Coast Types
Dalrymple et al, 1992
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Tidal Range and Coastal Morphology
Hayes, 1979
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CoastTypes
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Marine Depositional Systems

• wave-dominated coasts
• tide-dominated coasts
• fluvial-dominated coasts (deltas)
• carbonate reefs
• clastic shelves platforms
• carbonate shelves platforms
• deepwater fans
• pelagic abyssal plains

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Waves Wave Periods
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Characteristics of Beach Systems

• Sediments coarsen upward from marine shales
• Linear sand bodies parallel to basin margin,
  serrated margins landward
• Formed by a mix of waves and tidal currents
• Facies
• Subdivided erosion surfaces formed during
• Dropping in base level
• Local channels
• Rising in base level
• Wells sorted and rounded pure quartz arenites
  common
• Sedimentary structures
• Offshore hummocky wavy bedding
• Nearshore cut and fill
• Gently seaward dipping thin parallel beds
• Geometries
• Confined incised channels
• Open linear sheets parallel to shore
• Fauna flora
• Marine fauna at base of units
• Terrestrial flora at crest of units

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Vertical stacking of shore line sediments
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CoastTypes
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Beach Face - South Carolina Foreshore
Note High Energy Planar Beds
Photo G. Voulgaris
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Trough Cross-bed Current Ripples
Ordovician Near Winchester Kentucky
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Offshore Coastal Profile - Hummocky
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Coastal Profile
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Geomorphologyof Coast
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Coastal Morphology
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Coastal Profile and Lithofacies
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Coastal Lithofacies Architecture
Aigner Reineck, 1982
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CoastalLithofacies
Reineck Singh, 1980
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Coastal Lithofacies
Walker, 1984
Progradation
Transgression
Inlet
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Hayes, 1979
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Tide Versus Wave Domination
Hubbard et al., 1979
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Coastal Morphology
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Wave Dominated - Texan Coast
Note Storm Washover Serrated Back Barrier
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Wave Dominated - Texan Coast
Note Storm Washover Serrated Back Barrier
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Wave Dominated - Texan Coast
Note Storm Washover Serrated Back Barrier
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Wave Dominated - Texan Coast
Note Storm Washover Serrated Back Barrier
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Note Storm Washover On a Back Barrier
Pennsylvanian Wave Dominated Coast
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CoastTypes
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Chenier Coast Gulf of Carpentaria
Note Channels Reworking Chenier Plain
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Note Channels Reworking Barrier Islands
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Delta Mouth Bar - Kentucky
Note Incised Surface Of Reworked Bar
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Tidal, Storm or Tsunami Channel
Note Incised Surface Beneath Channel
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Characteristics of Sequence Boundary (SB) from
well logs, core outcrop

• Defined by erosion or incision of underlying
  flooding surfaces (mfs and TS)
• Inferred from interruption in the lateral
  continuity of these surfaces

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Characteristics of Sequence Boundary (SB) from
well logs, core outcrop

• Defined by erosion or incision of underlying
  flooding surfaces (mfs and TS)
• Inferred from interruption in the lateral
  continuity of these surfaces

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Beach Ridges St. Phillips Island, SC
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Progradation Transgressive Architectures
Kraft John, 1979
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Sea-Level Changes
Reading, 1986
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Tidal Bundles
Visser, 1980
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Bedforms Current Ripples
Sand in mud matrix
Sand predominates
Sand Mud 50/50
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Asymmetric Current Ripples
Upper Mississippian Pennington Formation Pound
Gap
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Base Level Change on Coast
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Tidal Geomorphology
Kraft et al, 1987
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Transitional Depositional Systems

• Estuaries
• Deltas

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Characteristics of Estuary Systems

• Sediments coarsen upward from marine shales
• Sand bodies perpendicular to basin margin, narrow
  landward
• Formed by a mix of tidal currents and occasional
  storm waves
• Facies
• Subdivided erosion surfaces formed during
• Dropping in base level
• Local channels
• Rising in base level
• Wells sorted and rounded pure quartz arenites
  common
• Sedimentary structures
• Offshore hummocky wavy bedding
• Nearshore cut and fill
• Gently seaward dipping thin parallel beds
• Geometries
• Confined incised channels
• Open linear sheets perpendicular and occasionally
  parallel to shore
• Fauna flora
• Marine fauna at base of units
• Terrestrial flora at crest of units

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Estuarine Lithofacies
Horne et al, 1978
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Marine Depositional Systems

• Wave-dominated coasts
• Tide-dominated coasts
• Fluvial-dominated coasts (deltas)
• Carbonate reefs
• Clastic shelves platforms
• Carbonate shelves platforms
• Deepwater fans
• Pelagic abyssal plains

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Deltaic Depositional Systems

• Form where rivers with large drainages meet
  standing water bodies (basins)
• Very large sediment flux
• Fluid gravity flow transport and deposition
• Surface waves
• Tidal waves (not tsunami!)
• Fluvial input
• Turbidity currents sub-aqueous debris flows
• Net sediment input often leads to progradational
  geometries
• Delta types depend on tidal range, wave climate,
  and composition and depths of water in river and
  basin

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Characteristics of Deltaic Systems

• Sediments coarsen upward from marine shales
• Sand bodies form tongues perpendicular to basin
  margin
• Formed by a mix of fluvial input, tidal currents
  and storm waves
• Facies
• Subdivided erosion surfaces formed during
• Dropping in base level
• Local channels
• Rising in base level
• Poorly sorted and irregular litharenites common
• Sedimentary structures
• Offshore laminated to hummocky wavy bedding
• Nearshore cut and fill
• Gently seaward dipping thin parallel beds
• Geometries
• Confined incised channels
• Open linear sheets perpendicular and occasionally
  parallel to shore
• Fauna flora
• Marine fauna at base of units
• Terrestrial flora at crest of units

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Coast Types
Dalrymple et al, 1992
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CoastTypes
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Lena River Delta - Russia
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Shattal ArabDelta
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Atachafalya Delta - USA
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Amazon Delta - Brazil
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Nile Delta - Egypt
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Delta Types

• River-dominated
• Small tidal range, weak storms and large sediment
  flux build delta out into basin
• Tide-dominated
• Large tidal ranges dominate transport, deposition
  geomorphology
• Wave-dominated
• Strong and repeated storms rework delta sediment

86
Delta Processes

• Depositional patterns and geomorphology depend on
  the relative dominance of three competing
  processes at river mouths
• Inertia
• River water
• Basin water
• Friction
• Water vs. substrate
• Water vs. water
• Buoyancy

87
Delta Processes

• Relative influence of inertia, friction
  buoyancy is a function of
• Density contrasts
• Homopycnal flow equal density water bodies mix
• Hyperpycnal flow higher density sinks below
  ocean (Yellow)
• Hypopycnal flow lower density floats on ocean
  (Mississippi)
• Concentration, grain size and suspended vs.
  bedload ratio
• Water depths
• Mouth
• Basin
• Water discharge
• Water inflow velocity

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Delta Processes

• Inertia-dominated deltas
• deep water, steep slopes, high river flow
  velocity
• moderate sediment transport, large flow expansion
• Friction-dominated deltas
• shallow water, low slopes,
• proximal sediment transport, large bars, limited
  flow expansion
• hyperpycnal flow possible
• Buoyancy-dominated deltas
• deep water, hypopycnal flow, large suspended load
• distant sediment transport, flow rafting ? plumes

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Delta Morphology
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River-Dominated Deltas
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Lobe-Switching
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Inter-distributary bays
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Mahakam River-Dominated Delta
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Wave-dominated Grijalva Delta
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Bramaputra Delta - India
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Tide-Dominated Niger Delta
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Tide-Dominated Niger Delta
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DeltaSuccessions
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Delta Succession
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Wave-DominatedDelta Succession
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Delta Collapse
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Delta Collapse
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Fan-Deltas
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Deltaic Succession
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Deltaic Succession
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Deltaic Succession
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Types of Depositional Systems

• marine ? ocean, sea
• terrestrial ? land
• transitional ? part land, part ocean

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Marine Depositional Systems

• wave-dominated coasts
• tide-dominated coasts
• fluvial-dominated coasts (deltas)
• carbonate reefs
• clastic shelves platforms
• carbonate shelves platforms
• deepwater fans
• pelagic abyssal plains

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Deep SeaDepositional Systems
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Deep Sea Depositional Systems
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Characteristics of Deepwater Systems

• Sediments fine upward from marine fans
• Sand bodies form lobes perpendicular to basin
  margin
• Formed by a mix of fluvial input, and turbidite
  currents
• Facies
• Subdivided erosion surfaces formed during
• Migrating fan lobe fill
• Dropping in base level
• Local channels
• Rising in base level
• Poor to well sorted litharenites common
• Sedimentary structures
• Fining upward cycles that coarsen up as
  depo-center of lobes migrate
• Up dip channel cut and fill
• Gently seaward dipping thin parallel lobate
  sheets
• Geometries
• Confined incised channels
• Open lobate sheets perpendicular and occasionally
  parallel to shore
• Fauna flora
• Restricted Marine fauna often in over bank shales

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Deep Sea Fan Depositional Systems

• Form in the moderate to deep ocean, down-dip of
  submarine canyons and often deltas
• Large sediment flux, high sedimentation rate,
  large area
• Gravity flow transport and deposition
• turbidity currents
• subaqueous debris flows
• suspension fall-out
• Lobes and lobe-switching important
• Both coarse and fine grained sediment
• Often well-sorted and normally graded

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Bengal Fan Ganges-Brahmaputra Delta
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Submarine Canyons and Deep Sea Fans
After Press Siever, 98
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Submarine Canyons
USGS Redondo Submarine Canyon, Southern Santa
Monica Bay
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USGS Image
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Submarine Canyons Deep Sea Fans
Offshore Los Angeles
USGS Image
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Submarine Fan Morphology
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SubmarineFan Types
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Turbidity Currents ? Turbidites
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Gravity Flows Turbidity Currents
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Turbidity Currents Hemipelagic Sediment
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Deep Water Fan Deposits
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Deep Water Fan Deposits
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Turbidites
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Coarse-grained Turbidites
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Coarse-grained Turbidites
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Turbidites
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Proximal Turbidites
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Distal Turbidites
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Soft-Sediment Deformation
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Submarine Channels
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Delaware Mountains Basin Fans
Deepwater Channel
Channel Sands
Kendall Photo
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Brushy Canyon Group - Base of Slope Permian Basin
Channel Fill Turbidites
Kendall Photo
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Brushy Canyon Group - Base of Slope - Permian
Basin
Margin of submarine fan channel incised into
"overbank". Channel fill with amalgamation as
well as flowage injection of sand into the
surrounding strata of the channel walls.
U.S. Highway 62-180 south of Guadalupe Pass
Kendall Photo
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Pelagic Depositional Systems

• Form in the open ocean or open (large) lakes and
  seas
• Small sediment flux, very low sedimentation rate
• Suspended load current transport
• Surface waves
• Tidal waves (not tsunami!)
• Fluvial input
• Turbidity currents sub-aqueous debris flows
• Suspension fall-out deposition
• Fine-grained (clay, mud and silt) deposition
• Carbonates
• Siliciclastic mudstones

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Pelagic Sediments
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Deep Marine Sedimentation
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Pelagic Sediments
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Calcareous Microfossils
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CCD
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Abyssal Plains
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Siliceous Microfossils
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Siliceous Microfossils ? Chert
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Siliceous Microfossils ? Chert
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Aeolian Dust
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Aeolian Dust
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Aeolian Dust
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Dropstones
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Types of Depositional Systems

• marine ? ocean, sea
• transitional ? part land, part ocean
• terrestrial ? land

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Terrestrial Depositional Systems

• Alluvial Fan
• Fluvial
• Glacial
• Eolian
• Lacustrine
• Playa

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Terrestrial Depositional Systems

• Alluvial Fan
• Fluvial
• Glacial
• Eolian
• Lacustrine
• Playa

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Alluvial Fan System Characteristics

• Sediments fine upward within fan lobes
• Sand bodies form lobes perpendicular to basin
  margin
• Formed by a mix of fluvial input, and mass
  sediment movement
• Facies
• Subdivided erosion surfaces formed during
• Migrating fan lobe fill
• Dropping in base level
• Local channels
• Rising in base level
• Poor to well sorted litharenite boulders, gravels
  and sands common
• Sedimentary structures
• Fining upward cycles that coarsen up as
  depo-center of lobes progrdes
• Up dip channel cut and fill
• Gently seaward dipping thin parallel lobate
  sheets
• Geometries
• Confined incised channels
• Open lobate sheets perpendicular and occasionally
  parallel to Mt front
• Fauna flora
• Terrestrial flora can be common in over bank
  lobes

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Alluvial Fan Depositional Systems

• Form upon exit of drainage basin from a mountain
  front
• Mix of sediment gravity flow fluid flow
  depositional processes
• Debris flows
• Hyperconcentrated flows
• Fluvial channels
• Sheetfloods
• Lobe-switching processes produce cone
• Radial sediment dispersal
• Decreasing grain size downslope

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exit gorge
active lobes
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Drainage Depositional Basins
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Alluvial Fan Architecture
Spearing, 1974
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Alluvial Fans
Blair McPherson. 1994
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Alluvial Fan Architecture
Kelly Olson, 1993
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Alluvial and Fluvial Fans

• Stream-dominated Alluvial Fans D 10 Km S
  5-15º
• Gravity-flow Alluvial Fans D 10 Km S
  5-15º
• Talus Cones D lt 1 Km S 10-30º
• Fluvial Megafans D 50 -100s Km S lt 1º

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Alluvial Fan Stratigraphy
Nemec Steel, 1984
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Stream-dominated AF Stratigraphy
Boothroyd, 1972
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Gravity-Flow AF Stratigraphy
Blair, 1987
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Alluvial Fan Architecture
Gloppen Steel, 1980
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Terrestrial Depositional Systems

• Alluvial Fan
• Fluvial
• Glacial
• Eolian
• Lacustrine
• Playa

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Fluvial System Characteristics

• Sediments fine upward within channel fill
• Sand bodies fine distally from channels
• Formed by a mix of fluvial bedload, and fine
  suspended sediment
• Facies
• Subdivided erosion surfaces formed during
• Migrating channel fill
• Dropping in base level
• Local channels
• Rising in base level
• Poor to well sorted litharenite gravels, sands
  and shales common
• Sedimentary structures
• Fining upward cycles that fill channels
• Up dip channel cut and fill
• Gently dipping thin parallel lobate sheets
  perpendicular to channels
• Geometries
• Confined incised channels
• Open lobate sheets perpendicular and occasionally
  parallel to channels
• Fauna flora
• Terrestrial flora can be common in over bank
  sediments

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Fluvial Depositional Systems

• Dominant conduit from regions of sediment
  production (mountains) to sediment storage
  (oceans, basins)
• Characterized by channel pattern
• Meandering
• Braided
• Anastomozing
• Characterized by sediment load
• Bedload
• Suspended load
• Mixed load
• Unidirectional sediment dispersal

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Fluvial Channel Patterns
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Fluvial Channel Patterns
Schumm Khan, 1972
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Meandering Streams
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Meandering Fluvial System
Allen, 1964
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Thalwegs
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Avulsion
Cross et al., 1989
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Meandering Fluvial Architecture
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Braided Fluvial Architecture
Nemec, 1992
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Fluvial Channels
Hirst, 1991
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Maturity
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Fluvial Characterization
Schumm, 1981
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Fluvial Channel Patterns
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Orton Reading, 1993
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Terrestrial Depositional Systems

• fluvial
• alluvial fan
• glacial
• eolian
• lacustrine
• playa

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GLACIERSAND GLACIATION
212
Past Glacial Periods

• Pre-Cambrian at end of Neoproterozoic eon
• End of the Ordovician
• Late Carboniferous (Pennsylvanian through
  Permian
• Pleistocene

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Glacial Periods
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The Snowball Earth

• During last ice age max, 21,000 years ago, North
  America Europe covered by glaciers over 2
  kilometers thick, sea level dropped 120 meters.
  Global chill land sea ice covered 30 t of
  Earth, more than at other times in last 500
  million years
• Near end of Neoproterozoic eon (1000-543 million
  years ago), glaciation immediately preceded first
  appearance of recognizable animal life some 600
  million years ago

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Paul Hoffman Daniel Schrag - Snowball Earth

• Sun abruptly cooled or Earth tilted on its axis
  or experienced an orbital blip that reduced solar
  warmth or carbon dioxide increased?
• ice sheets covered continents seas froze almost
  to equator, events that occurred at least twice
  between 800 million 550 million years ago
• Each glacial period lasted millions of years
  ended under extreme greenhouse conditions.
  Climate shocks triggered evolution of
  multicellular animal life, challenge long-held
  assumptions regarding the limits of global change

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SnowballEarth- Rocky cliffs along Namibia's
Skeleton Coast.
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SnowballEarth- Drop Stones
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Glacial System Characteristics

• Signal extremes in local climate sea level
  position
• Stratigraphic markers of glacial events
• Source of tillite (pebbles larger fragments
  supported in fine-grained matrix ) deposited from
  glaciers.
• Massive tillite inferred deposited below ice
  sheets or dropping from marine supported ice in
  submarine setting
• Banded tillite may be deposited by ice sheets
• Laminites common in lakes (Varve), Loess dust on
  land
• Supraglacial pro-glacial deposits with
  stratified conglomerates sandstone
• U Shaped valleys glacial striae
• Mountain glaciation could be source of much
  downslope fluvial sediment

220
Simplified Glacial Systems signals

• Sediment signal a mix of
• Glacial carried dumped in moraines
• Water born fluvial sediment
• Lacustrian varves
• Aeolian loess
• Erosion
• U-shaped valleys
• Eroded rock surface
• Grooved
• Plucked
• Striated
• Base level changes in sea level.

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Glacial Setting
Currently forms 10 of earthss surface,
Pleistocene reached 30, but in Pre Cambrian
could have reached 100

• Develop where all of annual snow doesnt melt
  away in warm seasons
• Polar regions
• Heavy winter snowfall e.g. Washington State
• High elevations e.g. even equator
• 85 in Antarctica
• 10 in Greenland

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Adelie Penguins Taking a Dive
223
Glacial Erosion

• Under glacier
• Abrasion plucking
• Bedrock polished striated
• Rock flour washes out of glacier
• Polishing and rounding
• Sheep Rocks
• Striations- scratches grooves on rock
• Above glacier
• Frost wedging takes place
• Erosion by glaciers steepens slopes

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Roche Moutone Ice Sheet Plucking
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Glacial Scarring Of Bedrock - Findelen
Glacier Switzerland - Matterhorn In Background
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Glacial Sediments

• Facies of continental glacial settings
• Grounded Ice Facies
• Glaciofluvial facies
• Glacial lacustrine facies
• Facies of proglacial lakes
• Facies of periglacial lakes
• Cold-climate periglacial facies
• Facies of marine glacial settings
• Proximal facies
• Continental Shelf facies
• Deepwater facies

227
Glacial Deposition

• Till
• Unsorted debris in fine matrix
• Erratic
• Moraine- body of till
• Lateral Moraine
• Medial Moraine- where tributaries join
• End moraine-
• Terminal
• Recessional
• Ground moraine
• Drumlin

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Twenty Mile Medial Moraine
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Robinson Tumbling Glacier Brit. Columbia
231
Ground and End Moraines
232
Glacial Lakes - Ireland
233
Glacial Sediments
234
Varves
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Glaciation Subdividing Surfaces
236
Glacial Sediments

• Facies of continental glacial settings
• Grounded Ice Facies
• Glaciofluvial facies
• Glacial lacustrine facies
• Facies of proglacial lakes
• Facies of periglacial lakes
• Cold-climate periglacial facies
• Facies of marine glacial settings
• Proximal facies
• Continental Shelf facies
• Deepwater facies

237
Glacial Systems - Conclusions

• Signal extremes in local climate sea level
  position
• Stratigraphic markers of glacial events
• Source of tillite (pebbles larger fragments
  supported in fine-grained matrix ) deposited from
  glaciers.
• Massive tillite inferred deposited below ice
  sheets or dropping from marine supported ice in
  submarine setting
• Banded tillite may be deposited by ice sheets
• Laminites common in lakes (Varve), Loess dust on
  land
• Supraglacial pro-glacial deposits with
  stratified conglomerates sandstone
• U Shaped valleys glacial striae
• Mountain glaciation could be source of much
  downslope fluvial sediment

238
Simplified Conclusions Glacial Systems

• Sediment signal a mix of
• Glacial carried dumped moraines
• Water born fluvial sediment
• Lacustrian varves
• Aeolian loess
• Erosion
• U-shaped valleys
• Eroded rock surface
• Grooved
• Plucked
• Striated
• Base level changes in sea level.

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AEOLIANAND DESERTS
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Sandy Desert N. Africa Going
241
Aeolian System Desert Coast

• Distribution of Aeolian systems Holocene
  Ancient
• Deserts Transport Depositional Sytems Wind
  Fluvial Action
• Deposits of Modern Deserts
• Dunes
• Interdunes
• Sheet Sands
• Aeolian Systems
• Bounding Surfaces
• Ancient Deposits

242
Simplified Desert Systems signals

• Sediment signal a mix of
• Aeolian sediment dunes and sheets
• Water born intermittent fluvial sediment
• Playas and lakes
• Aeolian loess
• Erosion
• Water table Stokes Surfaces marks limit
• Incised valleys
• Gravel remnants
• Rock pavements
• Ventifacts
• Base level changes in ground water level.

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Desert

• Region with low precipitation
• Usually less than 25 cm rain per year
• Distribution
• Most related to descending air
• Belts at 30 degrees North South latitude
• Rain shadow of mountains
• Great distance from oceans
• Tropical coasts beside cold ocean currents
• Polar desserts

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Earth'sGeneralCirculation
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Rain Shadow Deserts
248
Deserts Dune Factories
Common characteristics-

• Lack of through-flowing streams
• Internal drainage
• Local base levels
• Desert thunderstorms
• Flash floods
• Mudflows

Dominated by water transportation
249
Deserts Depositional Systems
Dunes fed by water transported sediment

• Margin rimmed by incised seasonal streams (Wadiis
  or Arroyo)
• In turn flanked by alluvial fans and rock
  pavements or bajada
• Intermittent drainage supplying sediment
• Dunes
• Playas

250
Bajada PedimentAlluvialFans -Namibia
251
Alluvial fans Death Valley
252
Salt Pan Alluvial Fans Death Valley
253
Sediment Source - Deserts Coasts

• Abundant sediment supply (sand, silt)
• Favorable wind regimes
• Grain transport in wind
• Transport populations resultant deposits
• i. Traction (deflation pavements)
• ii. Saltation (sand dunes)
• iii. Suspension (loess)
• III. Subenvironments of eolian dune systems

Dominated by water transportation
254
Wind Erosion and Transportation

• Sand
• Moves along ground- saltation
• Sandstorms
• Sandblasting up to 1 meter
• Ventifact
• Deflation
• Blowout
• Dust storms

255
Sand Movement
256
Brice Canyon - Utah
257
Arches National Park Utah
258
Wind Erosion and Transportation

• Dust storms
• Sand
• Moves along ground- saltation
• Sandstorms
• Sandblasting up to 1 meter
• Ventifact
• Deflation
• Blowout

259
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260
Wind Action

• Strong in desert because
• Low humidity
• Great temperature ranges
• More effective because of lack of vegetation
• Effective erosion in deserts because sediment is
  dry

261
Wind Erosion and Transportation

• Sand
• Moves along ground- saltation
• Sandstorms
• Sandblasting up to 1 meter
• Ventifact
• Deflation
• Blowout
• Dust storms

262
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263
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264
Wind Erosion and Transportation

• Sand
• Moves along ground- saltation
• Sandstorms
• Sandblasting up to 1 meter
• Ventifact
• Deflation
• Blowout
• Dust storms

265
Red Sea Dust Storm
RedSeaDustStorm
266
North Africa - Sea Dust Storm
267
Wind Erosion and Transportation

• Dust storms
• Wind-blown dust accumulates in the deep ocean
  floor at a rate of 0.6 x 1014 g/year.

268
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269
Loess
270
Wind Deposition

• Loess
• Gravel Pavements
• Desert varnish petroglyphs
• Sand Dunes
• Well-sorted, well-rounded sand grains
• Slip face
• Angle of repose
• Wind ripples

271
Desert Pavement Formation
272
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273
Wind Deposition

• Loess
• Gravel Pavements
• Desert varnish petroglyphs
• Sand Dunes
• Well-sorted, well-rounded sand grains
• Slip face
• Angle of repose
• Wind ripples

274
Wind Deposition

• Loess
• Gravel Pavements
• Desert varnish petroglyphs
• Sand Dunes
• Well-sorted, well-rounded sand grains
• Slip face
• Angle of repose
• Wind ripples

275
Barchan Dunes - Jordan
276
Zion National Park - Utah
277
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278
Wind Deposition

• Loess
• Gravel Pavements
• Desert varnish petroglyphs
• Sand Dunes
• Well-sorted, well-rounded sand grains
• Slip face
• Angle of repose
• Wind ripples

279
Dune Evolution
280
Hierarchies exhibited by aeolian and associated
sediments

• Grains
• Ripples
• Dunes
• Interdune unconfined sheets
• Confined bodies of wadii channel fills
• Playa unconfined sheets of heterogenous chemical,
  wind and water transported clastic sediments

281
Mechanisms of Aeolian Transportation

• Rolling 2-4 mm
• Surface creep
• 20-25 of sand moves by grains shifted by
  impacting saltating grains lt 2 mm
• Suspension fine sand, silt, clay
• Grains 0.1 mm are most easily moved by wind
  mostly gt 2 m above the ground surface

282
Mice Tracks RipplesWhite Sands, NM
283
Ripples on Dune
284
Wind Deposition

• Types of dunes
• Barchan
• Transverse dune
• Parabolic dune
• Longitudinal dune

285
Salt Pan West Texas, El Capitan
LONGITUDINAL
BARCHAN
PARABOLIC
TRANSVERSE
STAR
BARCHINOID
286
North Africa - Sea Dust Storm
Star Dunes Namibia
287
Sahara Barchans Camels
288
Navajo Sandstone
289
Cross-bedded Navaho Sandstone
290
NavajoSandstone
291
Quaternary of UAE Stokes Surface
292
NavajoSandstone
Base level change punctuates the sandstone with
erosion surfaces!
293
NavajoSandstone
Base level change punctuates the sandstone with
erosion surfaces!
294
NavajoSandstone
Base level change punctuates the sandstone with
erosion surfaces!
295
Some characteristics of deserts

• Stream channels normally dry
• covered with sand gravel
• Narrow canyons with vertical walls
• Resistance of rocks to weathering
• Desert topography typically steep and angular

296
Aeolian Sediment - Critical Character

• Aeolian sediments evidenced by x-bedding with
  high angle (30-34 degrees)
• Horizontal thin laminae common locally
• Sand rounded and frosted
• Quartz coated by iron oxide suggests hot arid
  and/or seasonally humid climate (exceptions)
• Well Sorted often unimodal but if bimodal two
  populations present
• Silt and clay minimal

297
Aeolian Sediment - Critical Character

• Small large scale cross bedding, with multiple
  orientations within horizontal bedding
• Grains in laminae well sorted, especially finer
  sizes, sharp differences in size between lamina
• Size ranges from silt (60 mu) to coarse (2mm)
• Max size transported by wind 1 cm but rare
  grains over 5 mm
• Larger grains (0.5 - 1.mm) often well rounded
• Sands free of clay and clay drapes rare
• Uncemented sands have frosted surfaces
• Mica usually absent

Rules of thumb - Glennie1970
298
Aeolian sediment interpretation

• Analyse sedimentology internal architecture
  with outcrop, cores and downhole imaging
• Identify seperate single aggradational units
  bounded by regional deflation surfaces
  (deep-scoured to flat surfaces)
• Genetic models from cyclic recurrence in facies
• Aggradation characterises near- continuous
  accumulation
• Internal facies evolution related to differences
  in sediment budget moving water table
• Palaeosols provide evidence of climate change

299
Conclusions - Desert Systems - Simplified

• Sediment signal a mix of
• Aeolian sediment dunes and sheets
• Water born intermittent fluvial sediment
• Playas and lakes
• Aeolian loess
• Erosion
• Water table Stokes Surfaces marks limit
• Incised valleys
• Gravel remnants
• Rock pavements
• Ventifacts
• Base level changes in ground water level.

300
LAKE AND ORGANICS
301
Lakes Are Ephemeral
302
Lacustrian Systems

• Critical characteristics of system?
• Geomorphologic tectonic setting
• Dominant sedimentary processes
• Facies
• Subdividing surfaces
• Lithology
• Sedimentary structures
• Geometries Confined versus open
• Fauna flora

303
Lake Systems Simplified Signals

• Sediment signal a mix of
• Lake Center sheets and incised unconfined
  turbidite cycles
• Margins marked by alluvial fans fluvial
  sediment
• Reducing setting that favors organic preservation
• Signal cycles in order from
• Clastics organics
• Limestone organics
• Evaporites organics
• Base level changes in ground water level
• Origin of large lakes
• Continental break up
• Continental collision
• Sags on craton

304
Significance of Lake Systems

• Signal extremes in local climate geochemistry
• Stratigraphic markers (Organics trap radioactive
  minerals)
• Major source of hydrocarbons along Atlantic
  Margins
• Major source of oil shale gas in western USA
  Canada
• Major source of
• Trona (Hydrated Sodium Bicarbonate Carbonate)
• Borax (Hydrated Sodium Borate)
• Sulfohalite (Na6ClF(SO4)2)
• Hanksite (Sodium Potassium Sulfate Carbonate
  Chloride)

305
Lake Geomorphologic Tectonic Setting
Temporary features forming 1 of earthss land
surface, filling-

• Major rifted, faulted (Break-up) continental
  terrains E. Africa
• Major final fill of foreland basin Caspian
  Aral
• Continental sags Victoria, Kenya, Uganda, and
  Eyre
• Glacial features including
• Moraine damming and/or ice scouring Great Lakes
  
• Ice damming
• Landslides or mass movements
• Volcanic activity including
• Lava damming
• Crater explosion and collapse Crater Lake
• Deflation by wind scour or damming by wind blown
  sand - Fayum
• Fluvial activity including
• Oxbow lakes
• Levee lakes,
• Delta barrier island entrapment

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307
Lake Tanganyika
308
Lake Tanganyika
309
Lake Tanganyika

• Lake levels have varied historical and earlier
• Fossil and living stromatolites abundant around
  the margins of Lake Tanganyika, Africa provides a
  source of paleolimnologic and paleoclimatic
  information for the late Holocene
• late Holocene carbonates suggests that the
  surface elevation of the lake has remained near
  the outlet level, with only occasional periods of
  closure
• In past the lake draw down encouraged evaporites

310
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311
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312
Lakes formed between splitting continents
313
Restricted Entrances To Sea
Isolated linear Belt of interior drainage
Regional Drainage Away From Margin
Organic Rich Lake Fill
Arid Tropics Air System
Wide Envelope of surrounding continents
314
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315
Lakes flanking Major Mountain Chains
316
Caspian and the Arral Sea

• Bodies of fresh to saline water trapped on craton
  behind major mountain chains
• Tend to act as traps to clastics, carbonates and
  evaporitic sediments
• Climatic change is recorded in the record of the
  sediment fill
• Water draw down encourages evaporites

317
Caspian
318
Aral Sea
319
Great Lakes
320
Great Lakes

• Bodies of fresh water trapped on glacially
  scoured depressions on craton behind glacial
  moraines
• Act as traps to clastic sediments
• Climatic change is recorded in record of sediment
  fill
• Water draw down encourages precipitates

321
Lake Constance - Switzerland
322
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323
Ice Dammed Lake Alaska
324
Lake Response to Stratification
325
Lake Sedimentary facies

• Sedimentary signal like that of a foreshortened
  Marine setting
• Narrow shores with beaches and deltas
• Finer sediments and turbidites fill the lake
  center

326
Lake Sedimentary facies

• Presence of freshwater fossils
• Lake sediments commonly better sorted than
  fluvial and periglacial sediments
• May (or may not) display a tendency toward fining
  upward and inward towards the basin center
• Lake sediments are predominantly fine grained
  sediments either siliciclastic muds but may be
  carbonate sediments and evaporates
• Typical sequence may produced as the lake dries
  up with a coarsening upward sequence from
  laminated shales, marls and limestones to rippled
  and cross-bedded sandstone and possibly
  conglomerates
• Lake sediment fill often shows cyclic alternation
  of laminae
• Varves produced by seasonal variations in
  sediment supply and lake circulation which
  changes the chemistry of the lakes

327
Lacustrian sedimentary geometries

• Shore marked by linear beaches
• Coarse to fine slope
• Deeper water lake laminae and turbidites
• Eclectic clastic and evaporitic sedments

328
GreenRiver Lake
329
Green River Lake Fill
330
Green River Systems Facies
331
Green River Section
332
Green River Section
333
Green River Section
334
Green River Fauna Flora
335
East African Lake Margin
336
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337
Green River Section
338
Conclusions - Lake Systems

• Sediment signal a mix of
• Lake Center sheets and incised unconfined
  turbidite cycles
• Margins marked by alluvial fans fluvial
  sediment
• Reducing setting that favors organic preservation
• Signal cycles in order from
• Clastics organics
• Limestone organics
• Evaporites organics
• Base level changes in ground water level
• Origin of large lakes
• Continental break up
• Continental collision
• Sags on craton

339
Lakes Are Ephemeral
340
End of the Lecture

• Lets go for lunch!!!