Geometry and development of glacial continental margin depositional systems in the Bellingshausen Sea
We present multi-channel seismic (MCS) reflection profiles and bathymetry data acquired across a remote and poorly surveyed part of the Antarctic continental margin in the Bellingshausen and Amundsen Seas. This new information has been combined with published data and used to interpret the style of sedimentation on the continental shelf, slope and rise, and to describe sedimentation processes which have been active in this region. Most seismic reflection profiles crossing the continental margin show prograded sequences beneath the outer shelf and upper slope, and we infer that the stratal characteristics of these sequences indicate that grounded ice sheets reached the shelf edge during previous glacial times. Although there are general similarities in stratal geometry on these profiles, in detail, they reveal significant longitudinal variations in sediment input from the shelf to the upper slope. On several profiles, we found evidence of mass wasting of the continental slope in the form of slump and debris flow deposits. At greater depth, turbidity flows, bottom currents and Coriolis force have controlled the further transportation and deposition of sediment, which has resulted in the development of mounds, channels and sediment wave fields. The distribution, and variations in the size and geometry of the mounds reflect sediment input and the relative contribution of these other factors which control sedimentation on the continental rise.
Authors: Nitsche, Frank O., Cunningham, Alex P., Larter, Rob D., Gohl, Karsten