StartGrid ViewAuthor Index View Uploaded Presentations Meeting Information
Paper No. 7
Presentation Time: 9:00 AM-6:00 PM

GLACIAL GEOMORPHOLOGY OF THE PENSACOLA MOUNTAINS, WEDDELL SEA SECTOR, ANTARCTICA


HEGLAND, Matthew1, VERMEULEN, Michael1, TODD, Claire2, BALCO, Greg3, HUYBERS, Kathleen4, CAMPBELL, Seth5, SIMMONS, Christopher6 and CONWAY, Howard7, (1)Department of Geosciences, Pacific Lutheran University, Tacoma, WA 98447, (2)Geosciences, Pacific Lutheran University, Tacoma, WA 98447, (3)Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709, (4)Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, (5)School of Earth and Climate Sciences, University of Maine, Orono, ME 04469, (6)Pro Guiding Service, Seattle, WA 98045, (7)Earth and Space Sciences & Quaternary Research Center, University of Washington, 63 Johnson Hall, Box 351310, Seattle, WA 98195, heglanmk@plu.edu

We mapped glacial geologic features in the Thomas, Schmidt, and Williams Hills in the western Pensacola Mountains. The three nunatak ranges are adjacent to the Foundation Ice Stream (FIS), which drains ice from the East and West Antarctic Ice Sheets (EAIS and WAIS), into the Filchner-Ronne Ice Shelf. Glacial deposits in the Pensacola Mountains record changes in the thickness of the FIS and provide insight into ice sheet history. Glacial scour on Mount Hobbs, Williams Hills suggests maximum ice thickness was at least 562 m greater than today and striations atop Martin Peak, Thomas Hills suggest ice there was at least 675 m thicker during a previous glacial maximum. Glacial striations oriented transverse to topography indicate that ice was thick enough to flow unconstrained over topography and suggest increased contribution from the EAIS. In the Schmidt and Williams Hills, depositional landforms are sparse with occasional highly-weathered erratics found over 100 m above the modern ice surface and relatively unweathered erratics deposited beside them below 100 m; these observations suggest preservation of older erratics in a cold-based environment. Upstream in the Thomas Hills, a highly-weathered till is present at all elevations; this deposit (a) has a high clay content, indicating wet-based ice, (b) has a highly-oxidized surface layer, and (c) includes highly-weathered surface boulders, indicating long-past thick ice cover. This till is sparsely covered at a range of elevations by erratics with different degrees of weathering. At low elevations in the Thomas Hills, greater depositional volume is observed in preserved moraines and relatively unweathered till that indicate multiple ice surfaces 20 - 100 m higher than the current ice surface; these features likely post-date the last glacial maximum. Preliminary numerical modeling of ice surfaces in the Thomas Hills suggest elevation changes could be attributed to local variations in ablation in addition to surface elevation changes in the FIS.

Session No. 96

T82. Geologic Maps, Digital Geologic Maps, and Derivatives from Geologic and Geophysical Maps (Posters)
Monday, 5 November 2012: 9:00 AM-6:00 PM
Hall B (Charlotte Convention Center)
Geological Society of America Abstracts with Programs. Vol. 44, No. 7, p.256
© Copyright 2012 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.
Back to: T82. Geologic Maps, Digital Geologic Maps, and Derivatives from Geologic and Geophysical Maps (Posters)
<< Previous Abstract | Next Abstract >>