HR: 14:40h
AN: C53A-05    [Abstracts]
TI: Evidence for organized subglacial meltwater drainage beneath the Pine Island and Marguerite paleo-ice streams, Antarctica following the Last Glacial Maximum
AU: * Anderson, J
EM: johna@rice.edu
AF: Rice University, Department of Earth Sciences, Houston, TX 77251-1892, United States
AU: Welln err, J
EM: jwellner@uh.edu
AF: University of Houston, Department of Geosciencs, Houston, TX 77204-5007, United States
AU: Clarke, G
EM: clarke@eos.ubc.ca
AF: University of British Columbia, Earth and Ocean Sciencs, Vancourver, BC V6T 1Z4, Canada
AB: Swath bathymetry records from the onset areas of two paleo-ice streams, the Pine Island and Marguerite ice streams, show geomorphic features suggestive of organized meltwater drainage systems. Radial, anastomosing and straight channels that link basins that are in excess of 800 meters deep characterize these systems. There is evidence that these drainage systems were active at the end of the Last Glacial Maximum, in the form of a well sorted silt unit, interpreted as a meltwater deposit, resting above till. This Radiocarbon ages from Marguerite Bay indicate that the ice sheet retreated rapidly from the bay about 9,000 years ago. Since that time the bay has remained ice-free, as evidenced by a surface unit of diatomaceous mud. In Pine Island Bay, the same stratigraphic succession occurs, but the meltwater deposits are the youngest deposits in the inner bay and a single radiocarbon date indicates a modern age for these deposits. These observations suggest that subglacial meltwater may have played a role in the retreat of these ice streams. In the case of Pine Island Bay, meltwater discharge occurred in modern times.
DE: 0700 CRYOSPHERE (4540)
DE: 0726 Ice sheets
SC: Cryosphere [C]
MN: 2007 Fall Meeting