Early Miocene glaciation in the Amundsen Sea, Southern Pacific: a Study of the distribution of sedimentary sequences

The distribution and internal architecture of seismostratigraphic sequences observed on the Antarctic continental slope and rise are results of sediment transport and deposition by bottom currents and ice sheets. Low energy input of detritus via a palaeo-delta originating in an area of the Amundsen Sea shelf and deposition of this material on the continental rise under sea ice coverage (60-21 Ma) was followed by glacial erosion in the hinterland of this part of West Antarctica (21-14.1 Ma), resulting in a larger depocentre and an increase in mass transport deposits. A higher sediment supply along a broad front with a focus via two palaeo-ice stream troughs resulted from a polythermal ice sheet. In the eastern Amundsen Sea rise the glaciogenic debris was shaped into levee-drifts by a re-circulating bottom current. A reduced sediment accumulation in the deep-sea subsequent indicates a reduced sediment supply probably in response to a colder and drier ice sheet (14.1-4 Ma). A dynamic ice sheet since 4 Ma delivered material offshore mainly via Abbott Trough and Pine Island Trough West. Interaction of this glaciogenic detritus with a west-setting bottom current resulted in the continued formation of levee-drifts in the eastern and central Amundsen Sea