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EAIS Stability Conclusions (Dry Valleys represent (Arena Valley, EAIS …
EAIS Stability Conclusions
Dry Valleys represent
→
Miocene landscape
Arena Valley, EAIS
stable for > 13 Ma
Volcanic ash
untouched for ~11.3 Ma
Taylor Glacier Moraine
Overlies ash
Dated ~3-4 Ma (Upper Pliocene)
Since Pliocene
Glacier thickened a bit
warmer & more moisture
that's all that's happned
Two steps cooling EAIS
34 Ma
Initial cooling
to form AIS
14 Ma
Ice extends to continental shelf edge
Probs ice assoc
w Dry Valleys
Sudden - terrestrial >10°C & ocean > 6°C
→ Before reducing to present extent
Two episodes glaciation
34 - 15 Ma
33 glacial-interglacial cycles
Orbitally-driven
Progressive cooling
13.6 Ma
to Present
Permanent ice sheet
retreated after advance
= controlling its high polar climate
Only subject to sealevel forcing
Octopus Evo
Strugnell 2012
Octopus genetic evolution ties into EAIS evo
35 Ma
First Antarctic cold-water octopus formed
Antarctic ice sheet formed
15 Ma
Octopus
split
into 3 sub-species
Pacific, Atlantic, Indian Oceans
Ice expands over continental shelf
∴ octopuses isolated in each ocaen
Why Pliocene diatoms in Sirius till?
Diatoms = wind blown from elsewhere
∴ EX-SITU & do not evince warm
EAIS Stability
McMurdo Dry Valleys
Stable climate since 14 Ma somehow...
Instability around
IS margins
somehow cannot have affected interior..