Glacial and glaciomarine environments in the southern Bellingshausen Sea since the last glacial maximum a reconstruction based on the sedimentary record

• Main Authors: Hillenbrand, C. D., Ó Cofaigh, C., Larter, R., Dowdeswell, J., Pudsey, C., Ehrmann, W., Grobe, Hannes
• Format: Conference Object
• Language: unknown
• Published: 2005
• Subjects: Antarctic; Bellingshausen Sea; Eltanin Bay; Ronne Entrance; West Antarctic Ice Sheet; Antarc*; Ice Sheet; Ice Shelf; Iceberg*
• Online Access: https://epic.awi.de/id/eprint/12148/; https://hdl.handle.net/10013/epic.22581

Multibeam swath bathymetric data and sub-bottom acoustic profiles collected during RRS James Clark Ross Cruise JR104 revealed the existence of a major glacial trough (Belgica Trough) on the West Antarctic continental shelf in the southern Bellingshausen Sea (75°-90°W, 69°-73°S), and of a trough mouth fan on the adjacent slope. Distinct seabed morphological features, such as mega-scale glacial lineations, drumlins and grounding-zone wedges, indicate that Belgica Trough represents the former pathway of a grounded ice stream, which had advanced to the shelf break during the last glacial maximum (LGM). Moreover, the orientation of the subglacial bedforms suggests that the ice stream was fed by grounded ice draining both through Eltanin Bay and Ronne Entrance, located to the south and south-east of Belgica Trough, respectively. These results give evidence that, in contrast to the present drainage pattern of the West Antarctic Ice Sheet, ice drainage to the southern Bellingshausen Sea played a significant role during the LGM.Sedimentary sequences recovered with gravity cores in the southern Bellingshausen Sea document a whole suite of (sub-)glacial and glaciomarine environmental settings. The lowermost units in the cores from the slope, the outer shelf and from Ronne Entrance consist of grey, massive, lithogenic diamictons. The diamictons on the slope represent glaciogenic debris flow deposits (GDFs), consisting of the detritus initially delivered by the grounded ice stream to the shelf edge during the LGM. In contrast, the lithologically very similar diamictons on the shelf are interpreted as deformation tills deposited directly by the grounded ice, and as glaciomarine tills deposited during the subsequent deglaciation phase, respectively. The glaciomarine tills may comprise both sub-ice shelf tills as well as iceberg-rafted tills and thus reflect the retreat of grounded ice. The lowermost sediments in cores recovered from Eltanin Bay consist of grey-olive, lithogenic, massive to stratified gravelly muddy sands, ...