HR: 1330h
AN: C43A-07    [Abstracts]
TI: Are Eastern Basin (Ross Sea, Antarctica) Bathymetric Ridges Associated With the Last Glacial Maximum?
AU: * Chow, J M
EM: jchow1@lsu.edu
AF: Louisiana State University, Department of Geology and Geophysics, E235 Howe-Russell Geoscience Complex, Baton Rouge, LA 70803 United States
AU: Bart, P J
EM: pbart@geol.lsu.edu
AF: Louisiana State University, Department of Geology and Geophysics, E235 Howe-Russell Geoscience Complex, Baton Rouge, LA 70803 United States
AB: Ross Sea (Antarctica) Eastern Basin bathymetric ridges have been interpreted to be ice stream divides created during the Last Glacial Maximum (LGM) advance of the Antarctic Ice Sheet based on radiocarbon dating of organic matter from near-seafloor sediments recovered in piston cores (Domack et al., 1999). Detailed seismic correlations and contour mapping show that there are at least five thick units outcropping in Eastern Basin. Four of these seismically-defined units can be correlated to age control at DSDP sites 270 and 272. In contrast to the near-seafloor sampling, the interiors of these units were initially assigned a Pliocene age based on a variety of microfossil biozones (Hayes and Frakes, 1975). Savage and Ciesielski (1983) determined that the youngest unit was deposited during the Coscinodiscus lentiginosus (since renamed Thalassiosira lentiginosa) diatom biozone (i.e., the unit formed sometime between 0.65 Ma to Recent timeframe). Thus, seafloor units in the area probably are of Quaternary age, but not necessarily LGM age. More recently, diatom biozonations for the Southern Ocean have been revised to provide more detailed biochronostratigraphic resolution (Zielinski and Gersonde, 2002; Zielinski et al., 2002). We are using the most recently-revised Southern Ocean diatom-zonation schemes to systematically evaluate ages of samples taken from the base of piston cores penetrating the five individual seismically-defined units in Eastern Basin. Using this sampling strategy, we increase the chances of penetrating through the Recent hemipelagic drape to sample the underlying seismically-defined units.
DE: 3022 Marine sediments--processes and transport
DE: 3030 Micropaleontology
DE: 3045 Seafloor morphology and bottom photography
DE: 9310 Antarctica
SC: Cryosphere [C]
MN: 2005 Joint Assembly