Geometry and development of glacial continental margin depositional systems in the Bellingshausen Sea

We present multi-channel seismic (MCS) reflection profiles and bathymetry d ata acquired across a remote and poorly surveyed part of the Antarctic cont inental margin in the Bellingshausen and Amundsen Seas. This new informatio n has been combined with published data and used to interpret the style of sedimentation on the continental shelf, slope and rise, and to describe sed imentation processes which have been active in this region. Most seismic re flection profiles crossing the continental margin show prograded sequences beneath the outer shelf and upper slope, and we infer that the stratal char acteristics of these sequences indicate that grounded ice sheets reached th e shelf edge during previous glacial times. Although there are general simi larities in stratal geometry on these profiles, in detail, they reveal sign ificant longitudinal variations in sediment input from the shelf to the upp er slope. On several profiles, we found evidence of mass wasting of the con tinental slope in the form of slump and debris flow deposits. At greater de pth, turbidity flows, bottom currents and Coriolis force have controlled th e further transportation and deposition of sediment, which has resulted in the development of mounds, channels and sediment wave fields. The distribut ion, and variations in the size and geometry of the mounds reflect sediment input and the relative contribution of these other factors which control s edimentation on the continental rise. (C) 2000 Elsevier Science B.V. All ri ghts reserved.