Tuesday, 28 August 2007 - 11:30 AM
2.A.A-5
East Antarctic ice-sheet dynamics 5.2-0 Ma from a high-resolution terrigenous particle size record, ODP Site 1165, Prydz Bay-Cooperation Sea
Sandra Passchier, Earth and Environmental Studies, Montclair State University, Mallory Hall 252, 1 Normal Ave, Upper Montclair, NJ 07043
This paper discusses a 5.2-0 Ma high-resolution terrigenous particle size record in a sediment drift off East Antarctica. The particle size properties of Hole 1165B are interpreted in the context of previously acquired data on a continental shelf to slope transect drilled by ODP Leg 188 in Prydz Bay and the Cooperation Sea. The new data indicate that the ice sheet stayed predominantly landward of the shelf break in the early Pliocene (5.2-3.5 Ma) with periods of ice sheet recession on land. The middle Pliocene (3.5-3.1 Ma) is characterized as major ice-sheet expansion with deposition of meltwater plumites on the continental rise. By 2.5 Ma the ice-sheet had become stable and dry-based with ice flow in a glacial trough extending to the shelf break. Pulses of coarse-grained glacigenic debris after ~ 1 Ma are interpreted as extensive calving in response to Northern Hemisphere deglaciations and subsequent sea level rise.