HR: 0830h
AN: PP31C-0270    [PDF]
TI: Late Miocene (?) expansion of the East Antarctic Ice Sheet across Mawson Bank, North basin Ross Sea
AU: Warny, S
EM: swarny@lsu.edu
AF: Louisiana State University Department of Geology and Geophysics, E235 Howe-Russell, 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, Baton Rouge, LA 70803 United States
AB: Subglacially-erupted volcanics on Coulman Island and Hasslett Peninsula led Hamilton (1972) to conclude that an inflated East Antarctic Ice Sheet (EAIS) advanced over the Transantarctic Mountains and grounded on the North Basin outer continental shelf during the late Miocene, i.e., at ~5.4 Ma. A large depocenter located on the North Basin outer shelf (ANTOSTRAT, 1995) contains several toplap unconformities presumably eroded by the EAIS (ANTOSTRAT, 1995; Bart et al., 2000). One of the unconformities (unconformity 10 from Bart et al., 2000) is unusual in that it deeply erodes into the underlying strata. Furthermore, toplap termination extends to the shelf edge suggesting an anomalous advance with respect to subsequent EAIS advances. Unfortunately, seismic correlation to DSPD Site 273 only constrains the unconformity to be younger than middle Miocene (i.e., $<$14.7 Ma according to Savage and Cielsielski, 1983) and thus it is not possible to determine if this unsual erosional horizon is indeed correlative with the EAIS over-riding event proposed by Hamilton (1972). During the past field season (2003), we acquired a grid a piston cores across the outer part of Mawson Bank where unconformity 10 has not been buried and thus, upper-Miocene strata are presumably exposed at the sea floor. In our ongoing study of these cores, we are conducting palynological analyses to determine if indeed the samples are from strata of upper-Miocene age.
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting