HR: 14:30h
AN: C43B-05    [Abstracts]
TI: Antarctic Peninsula Ice Sheet Grounding Events on the Pacific-Margin Continental Shelf During the Late Miocene/Early Pliocene Compared to two Drift-Derived Proxies on the Adjacent Continental Rise
AU: * Bart, P J
EM: pbart@geol.lsu.edu
AF: Louisiana State University, Department of Geology and Geophysics, Baton Rouge, La 70803 United States
AU: Warny, S A
EM: sophie@geol.lsu.edu
AF: Louisiana State University, Museum of Natural Science, Baton Rouge, La 70803 United States
AB: We compared the record of Antarctic Peninsula Ice Sheet (APIS) grounding events derived from the outer-continental-shelf stratigraphy with the glacial history deduced from two drift-sedimentology proxies within coeval section on the adjacent continental rise. On the outer continental shelf, detailed seismic-stratigraphic mapping and correlations (Bart et al., in review) to glaciogenic sediments at ODP Leg 178 Site 1097 (Eyles et al., 2001) shows that there were at least 13 major cycles of APIS advance and retreat on the Pacific-margin during the late Miocene/early Pliocene. The age constraints are based on diatom biozonations from Winter and Iwai (2001). At ODP Leg 178 Site 1095 on the adjacent continental rise, the coeval section sampled from a large drift exhibits distinct meter-scale bioturbation events capping thick (up to 20 m) unbioturbated terrigenous sections that were interpreted by Pudsey (2001) to result from 36 glacial/interglacial cycles. Within the same section, Hillenbrand and Ehrmann (2001) recognize two distinct clay-mineralogy assemblages (based on ratios of smectite and chlorite) from which they deduce that there were 14 glacial/interglacial cycles. Our preliminary comparison (on a diatom biozone-to-biozone basis) of continental-shelf and continental-rise data suggests that there is no clear relationship between the number of APIS grounding events and these two sedimentologic-based proxies (bioturbation and clay mineralogy) on the adjacent continental rise.
DE: 1620 Climate dynamics (3309)
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 3025 Marine seismics (0935)
DE: 3344 Paleoclimatology
DE: 9310 Antarctica
SC: Cryosphere [C]
MN: 2005 Joint Assembly