The Antarctic Glacial Geologic Record and GCM Modeling: A Test,
OHIO STATE UNIV COLUMBUS
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A recent GCM General Circulation Model study of Antarctic glaciation by Oglesby concluded that 1 oceanic heat transport is relatively unimportant in the development and maintenance of Antarctic glaciation 2 height and polar position, not the Antarctic Circumpolar Current, have led to thermal isolation and 3 surface elevation may be crucial for glaciation. Model results are here evaluated against the Pliocene geologic record for Antarctica. The Sirius Group, widely distributed in the Transantarctic Mountains, contains diatom floras suggesting open marine conditions in interior East Antarctica as recently as about 3 m.y. ago. The Sirius deposits also contain a sparse fossil flora including Nothofagus wood, demonstrating snow-free conditions and elevated summer temperatures within 500 km of the South Pole. Based on fission track data and marine sediments, uplift rates for the Transantarctic Mountains are estimated to average 50-100 m m.y.-1 for the last 10 m.y., although rates may have been higher during the last 3 m.y. The continental interior is also most unlikely to have changed elevation by more than a few hundred meters in the last 3 m.y. If the dating of the Sirius is correct and uplift rates have not been an order of magnitude higher, then polar location and elevation cannot be primary controls on the formation and subsequent fluctuations of the ice sheet.
- Geology, Geochemistry and Mineralogy
- Snow, Ice and Permafrost