New insights into Quaternary glacial dynamic changes on the George V Land continental margin (East Antarctica)

Abstract

The continental margin of the George V Land represents the seaward termination of one of the largest sub-glacial basins (the Wilkes Basin) of the East Antarctic Ice Sheet (EAIS) and hence is a potentially useful site for the investigation of the Cenozoic glacial history of Antarctica. Because the seafloor morphology relates strictly to recent glacial marine sedimentary processes, we have compiled all available echo-soundings data collected until the year 2001 and integrated the data set with satellite altimetry data. As a result, we have produced a new bathymetric map of the margin, covering an area of more than 80,000 km 2 with a spatial resolution of about 1 km. The bathymetric data have been integrated with sub-bottom profiler data with the purpose of defining sedimentary processes and their variations during the Quaternary. The continental shelf of the Wilkes Land margin is characterised by alternating banks and glacial troughs connected to sub-marine canyons that cut into the continental slope. Our study focussed on the continental rise, where asymmetrical ridges alternate with large deep-sea channels. The ridges have a long gentle eastern side and short steep western side, with axis elongated approximately in north–south direction, perpendicular to the margin. The channels represent the main sediment drainage pattern feeding the ridge depositional system found along the continental rise. The sediment is supplied to the continental shelf edge by ice sheets, and sediment gravity flows are considered the main process for sediment supply to the rise. The modern sedimentary environment of the deep margin is affected by turbiditic down-slope sediment transfer with a minor contribution from along-slope contour currents. The WEGA channel is currently affected by transport and settling of sediment through High-Salinity Shelf Water (HSSW), originating on the continental shelf. We infer that thermohaline circulation has contributed to sediment transport and deposition since the mid-Pleistocene.