Glacial Sedimentation

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Glacial Sedimentation
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Sedimentation in Polar Settings
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Cold water carbonates
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Glacial Erosion

• Abrasion is a slow process that involves
  sandpapering of rock to produce rock flour
• Plucking is a much faster means of erosion which
  involves freezing and thawing (frost wedging)
  which results in large chunks of rock being
  rafted from the bed

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Glacial erosion by abrasion and plucking
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U-Shaped valleys are one of the most diagnostic
geomorphic features of glaciation
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The Glacial Buzz saw
Equilibrium Line Altitude ELA
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The Antarctic Peninsula
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Patagonia
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Variable accumulationrates with changing
latitude
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The Ice Sheet Conveyer Belt(Deforming
Beds)Perhaps the dominantmechanism in
sedimentdelivery to the margin
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Strike view of shelf showing unconformities with
cross-section profiles similar to modern troughs
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Cross-shelf seismic profile showing landward
sloping glacial erosion surface
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Tills
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Basal Debris Transport
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Lodgement Mechanism(Pressure-regelation)
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Lodgement Till

• Stiff (high shear strength)
• Lack of sorting
• Textural and mineralogical homogeneity
• Till provenance
• Pebble shape and fabric

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Seismic Facies

• Till tongues are wedge-shaped seismic units with
  chaotic reflection patters
• Glaciomarine deposits are characterized by more
  stratified seismic facies

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Tills (lodgement and deformation)are
characterized by a lack of sorting
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Particle Shape andSurface Textureleft-large
clasts eroded from tilllower left-boulder with
facets and striationslower right-striations on
boulder
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PebbleShapeClasts transported at baseof
glacier are more rounded than englacial and
supraglacial clasts
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Pebble FabricElogate pebbles aligned in
direction of ice flow
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Silt grains with facets, striations, and
concoidal fractures
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Till Composition - homogenization of sediment
results in uniform grain size and mineralogy
within a till unit
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Glacimarine Sedimentation
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Glaciomarine Sedimentation
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Iceberg Concentrations
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GlaciomarineSeismicfacies
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Crude stratificationand sorting
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Sedimentation Models
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Using glacial sedimentology to solve some
important problems
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History and mechanisms of ice sheet retreat
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Sedimentary record of slow ice sheet retreat
versus decoupling
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Glacial response to climate change in the
Antarctic Peninsula
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Polar Versus Temperate Glaciers
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Climate control on fjord sedimentation
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Shaldril
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