Laurentide Deglaciation

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Laurentide Deglaciation

• CLIMAP Model 18 ka BP
• Constrained by 14C dates
• Constrains area, not volume

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Fennoscandian Ice Sheet - decay

• 2nd largest Pleistocene I.S.

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Fennoscandian Ice Sheet - decay

• 2nd largest Pleistocene I.S.
• Ongoing uplift
• Complex deglacial history

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Fennoscandian Ice Sheet - decay

• 2nd largest Pleistocene I.S.
• Ongoing uplift
• Complex deglacial history
• Complex margins
• British Isles
• Barents Sea

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Barents Ice Sheet

• Contiguous with Fennoscandian
• Fully marine-based unstable!
• Poorly defined eastern margins
• May have dammed major N-flowing rivers

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http//www.uwgb.edu/dutchs/EarthSC202Notes/GLACgeo
g.HTM
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Marine-based ice sheet analogs

• West Antarctic ice sheet
• Barents shelf / ice sheet

Seigert et al., (2002), American Scientist
Volume 90 Number 1 Page 32
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Growth of marine-based ice sheets

• Grounding of thickening floating ice shelf?
• How maintain against calving?
• Effects of isostasy/eustasy?

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Barents History

• Recon-structed through modeling

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Barents History

• Recon-structed through modeling

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Pre-Pleistocene Glaciations

• Pleistocene latest
• Permo-Carboniferous
• Sil-Ordovician
• Proterozoic (late, early)

Permo-Carboniferous glaciation
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Major phases of Late Proterozoic glaciation
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Early Proterozoic Glaciation

• Evidence in Gowganda Formation north of Lake
  Huron
• Conglomerates (tillites) alternate with laminated
  mudstones (varved)
• Conglomerate clasts are scratched and faceted
• Igneous rocks (2100 my) intrude and Formation
  rests upon crystalline basement (2600 my).
• Similar rocks in Finland, southern Africa,
  India.

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Snowball Earth?

• Worst (best?) case scenario
• Inferred from glacial deposits at or near the
  paleomagnetic equator
• Modeled as a result of complete consumption of
  early CO2 through weathering.

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