La Macchia, C.; De Santis, L. (2000): Seismostratigraphic sequence analysis in the Prydz Bay area (East Antarctica). Terra Antartica Publication, Siena, Italy, In: Brambati, Antonio (editor), Proceedings of the workshop; Palaeoclimatic reconstructions from marine sediments of the Ross Sea (Antarctica) and Southern Ocean, 4, 259-267, georefid:2008-094539

A seismostratigraphic sequence analysis was made in the Prydz Bay area in the east Antarctica coast, at the seaward end of the Lambert glacier which drains 22% of the present eastern ice sheet. The seafloor in Prydz Bay is characterized today by a broad topographic basin, the Amery Depression. The continental shelf edge shallows to less than 200 m of water depth on the eastern and on the western side of the Prydz Channel. A backstripping technique was used to a seismic line that runs from the inner continental shelf, across the Prydz Channel, to the shallow outer shelf, and intersects the ODP drill sites. The aim of this study was to reconstruct the paleogeography of the continental shelf at significant stages of its evolution and to discuss the implications on the ice sheet configuration. The first evidence of overdeepening and landward reverse profile of the sea floor and the causes of the strata pattern within late Eocene-Early Oligocene to the Holocene and late Miocene to Holocene are investigated in particular at the formation time of some of the most significant unconformities at various depths. Several conclusions are made: the Prydz Bay was characterized by a sub-aerial and shallow continental shelf until the mid-Cenozoic. At ca 50 Ma glaciers were already grounding below the sea level, but the continental shelf was not overdeepened like today. At this time Prydz Bay was characterized by a shallow, temperate-cool, fjord-terrestrial environment rather than that dominated by a large ice sheet; the oldest, well-documented, major, erosional event, likely due to the expansion of thick grounding ice up to the continental shelf break, occurred in the mid to late Miocene. It caused the overdeepening of the sea floor profile, removing most of the sediments from the continental shelf. Such a major change in the continental shelf profile probably represents a significant and continental scale variation in the ice sheet configuration, because it has been observed also in other regions of the Antarctic margin. (LEL)
West: 75.0454 East: 75.2417 North: -67.1634 South: -67.3259
Expedition: 119
Site: 119-739
Site: 119-742
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