Sedimentology of the southern Bellingshausen Sea

• Main Authors: Hillenbrand, Claus-Dieter, Larter, Robert D, Dowdeswell, Julian A, Ehrmann, Werner, Ó Cofaigh, Colm, Benetti, Sara, Graham, Alastair G C, Grobe, Hannes
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 2010
• Subjects: ANT-XI/3; AWI_Paleo; BC; BC355 CORE_NO 355; BC356 CORE_NO 356; BC361 CORE_NO 361; BC361Y; BC363 CORE_NO 363; BC364 CORE_NO 364; BC364X; BC369 CORE_NO 369; BC369X; BC369Y; BC373 CORE_NO 373; BC373Y; Bellingshausen Sea; central axis of trough; middle shelf; outer shelf; deep part of trough in Eltanin Bay; eastern bank of mini trough; inbetween gullies at uppermost slope on TMF; part of trough exiting Carroll Inlet; MSGL/drumlins trend 335¡; ridge-groove province: flattish groove; ridge-groove province: ridge; shallow part of trough in Eltanin Bay; small escarpment at shelf break; till sheet on N side of Ronne Entrance Trough; till sheet on shelf N of Smyley Island; toe of eastern bank of mini trough; western flank of trough; Antarc*; Antarctic; Antarctic Peninsula; Antarctica; Ice Sheet; Ice Shelf; Ronne Entrance; Smyley Island; West Antarctica
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.742532; https://doi.org/10.1594/PANGAEA.742532

A major trough ('Belgica Trough') eroded by a palaeo-ice stream crosses the continental shelf of the southern Bellingshausen Sea (West Antarctica) and is associated with a trough mouth fan ('Belgica TMF') on the adjacent continental slope. Previous marine geophysical and geological studies investigated the bathymetry and geomorphology of Belgica Trough and Belgica TMF, erosional and depositional processes associated with bedform formation, and the temporal and spatial changes in clay mineral provenance of subglacial and glaciomarine sediments. Here, we present multi-proxy data from sediment cores recovered from the shelf and uppermost slope in the southern Bellingshausen Sea and reconstruct the ice-sheet history since the last glacial maximum (LGM) in this poorly studied area of West Antarctica. We combined new data (physical properties, sedimentary structures, geochemical and grain-size data) with published data (shear strength, clay mineral assemblages) to refine a previous facies classification for the sediments. The multi-proxy approach allowed us to distinguish four main facies types and to assign them to the following depositional settings: 1) subglacial, 2) proximal grounding-line, 3) distal sub-ice shelf/subsea ice, and 4) seasonal open-marine. In the seasonal open-marine facies we found evidence for episodic current-induced winnowing of near-seabed sediments on the middle to outer shelf and at the uppermost slope during the late Holocene. In addition, we obtained data on excess 210Pb activity at three core sites and 44 AMS 14C dates from the acid-insoluble fraction of organic matter (AIO) and calcareous (micro-)fossils, respectively, at 12 sites. These chronological data enabled us to reconstruct, for the first time, the timing of the last advance and retreat of the West Antarctic Ice Sheet (WAIS) and the Antarctic Peninsula Ice Sheet (APIS) in the southern Bellingshausen Sea. We used the down-core variability in sediment provenance inferred from clay mineral changes to identify the most reliable AIO ...