In Vincennes Bay (East Antarctica), glacial erosion has produced an over-deepened glacial trough on the inner shelf, up to 2,100 m in depth locally, and most of the inner shelf area is characterised by exposed basement rocks as seen on GI-gun seismic profiles. Glacial marine sedimentation processes in the bay are characterised by siliciclastic sediments dominating over biogenic sediments even in deep, inner shelf troughs. Sediments deposited in 475 to 592 m water depth on Petersen Bank exhibit massively bedded diamictons overlain by a thin layer (<20 cm thickness) of siliceous mud and diatom ooze (SMO) and one core had no SMO layer, suggesting that these sites have been subjected to iceberg turbation. Analysis of cores collected from the inner shelf glacial trough suggests an east-west variation in Holocene biogenic sediment supply. Diatom fragments dominate over whole diatoms except at the westernmost site where diatom abundance exceeds terrigenous grain abundance at all levels in the core. Terrigenous sediment sourced from the Vanderford Glacier is dispersed southwestwards by ocean currents. It accumulates in deep valleys but other areas of exposed bedrock appear to be clear of any significant sediment deposits. Perched basins appear to be a local sediment trap with as much as 60 m thickness of unconsolidated sediment (interpreted from seismic data). Downcore variations in sediment properties and magnetic susceptibility are attributed to late Holocene changes in the relative biogenic/terrigenous sediment supply.
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|Published - 1997