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North-Central Section - 43rd Annual Meeting (2-3 April 2009)

Paper No. 5
Presentation Time: 9:40 AM

WEST ANTARCTIC ICE SHEET (WAIS) HISTORY FROM THE DIATOM RECORD OF THE ANDRILL - McMurdo ICE SHELF PROJECT


SCHERER, Reed P.1, WINTER, Diane2, SJUNNESKOG, Charlotte3, RIESSELMAN, Christina4 and KONFIRST, Matt1, (1)Geology and Environmental Geosciences, Northern Illinois University, DeKalb, IL 60115, (2)Department of Geosciences, University of Nebraska-Lincoln, Lincoln, NE 68588, (3)Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803, (4)Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305, reed@niu.edu

Stratigraphic drilling near Ross Island, Ross Sea, Antarctica recovered 1,284 m sediment core with 98% recovery. The upper 600 m included a remarkable Pliocene and Pleistocene record of repeated advance and retreat of the West Antarctic Ice Sheet. The ANDRILL-MIS core demonstrates that the WAIS has a history of dynamic behavior over at least the last 5 Ma, but details of the Late Pleistocene history remain sketchy.

Diatoms are the key data source for paleoenvironmental interpretation. Interglacials with reduced glacial ice are characterized by pelagic diatom-rich sediments, frequently with reduced sea-ice relative to today, as inferred from the diatom assemblages. The Early Pliocene included an extended interval of warmer than present conditions with thick intervals of pure diatomite accumulation, and the Late Pliocene was characterized by dramatic obliquity-paced glacial-interglacial cycles. The most recent unequivocal collapse of the WAIS was during Marine Isotope Stage 31, ~ 1 million years ago, a time of intense solar insolation. Collapse of the WAIS during late Pleistocene interglacials remains equivocal. The upper 29 m of core were not recovered, and the interval from 29 to 58 m below sea floor is composed of glacial diamictons lacking age control and containing few or no diatoms.

Session No. 3

T5. Climate Change
Thursday, 2 April 2009: 8:00 AM-12:00 PM
Geological Society of America Abstracts with Programs. Vol 41, No. 4, p.7
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