Tuesday, 28 August 2007 - 10:30 AM
2.A.A-2
Glacial dynamics of the West Antarctic Ice Sheet in the southern Bellingshausen Sea during the last glacial cycle
Claus-Dieter Hillenbrand1, Sara Benetti2, Werner Ehrmann3, Robert D. Larter1, Colm O'Cofaigh4, Julian A. Dowdeswell5, Hannes Grobe6, and A.G.C. Graham1. (1) Geological Sciences Division, British Antarctic Survey, High Cross, Madingley Road,, Cambridge, CB3 0ET, United Kingdom, (2) Marine Institute, AMS - Ocean Science Services, Rinville, Oranmore, Ireland, (3) Institute for Geophysics and Geology, Leipzig University, Talstrasse 35, Leipzig, D-04103, Germany, (4) Department of Geography, University of Durham, South Road, Durham, DH1 3LE, United Kingdom, (5) Scott Polar Research Institute, University of Cambridge, Lensfield Road, Cambridge, CB2 1ER, United Kingdom, (6) Alfred Wegener Institute for Polar and Marine Research, Am Alten Hafen 26, Bremerhaven, D-27568, Germany
A major glacial trough ("Belgica Trough") on the continental shelf in the southern Bellingshausen Sea acted as an important outlet for ice draining the West Antarctic Ice Sheet during the Last Glacial Maximum (LGM). Mega-scale glacial lineations, drumlins and grounding-zone wedges indicate that Belgica Trough represents the former pathway of a grounded ice stream, which advanced to the shelf break during the LGM and was fed by ice draining through Eltanin Bay and Ronne Entrance. Here we present the preliminary results of sedimentological investigations carried out on 26 sediment cores recovered from the shelf and slope. This unique dataset allows the identification of various facies types that reflect the different phases of grounded ice advance, retreat, and post-glacial onset of seasonal open-water conditions. We will reconstruct the complex processes of erosion, transport and (re-)deposition controlling sedimentation on the margin and the timing of ice-sheet retreat from the shelf.