Clay mineralogy and shear strength of subglacial and glaciomarine sediments in the southern Bellingshausen Sea

• Main Authors: Hillenbrand, Claus-Dieter, Ehrmann, Werner, Larter, Robert D, Benetti, Sara, Dowdeswell, Julian A, Ó Cofaigh, Colm, Graham, Alastair G C, Grobe, Hannes
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 2009
• Subjects: ANT-XI/3; AWI_Paleo; BC; BC351 CORE_NO 351; BC356 CORE_NO 356; BC361 CORE_NO 361; BC363 CORE_NO 363; BC364 CORE_NO 364; BC369 CORE_NO 369; BC373 CORE_NO 373; BC379 CORE_NO 379; Bellingshausen Sea; bank west of channel on TMF; central axis of trough; middle shelf; outer shelf; deep part of trough in Eltanin Bay; eastern bank of mini trough; 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; slope on TMF; small escarpment at shelf break; steep slope east of TMF; till sheet on N side of Ronne Entrance Trough; till sheet on shelf N of Smyley Island; toe of eastern bank of mini trough; upper slope on Trough Mouth Fan (TMF); Antarc*; Antarctic; Ice Sheet; Ronne Entrance; Smyley Island; Southern Ocean
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.711173; https://doi.org/10.1594/PANGAEA.711173

The Belgica Trough and the adjacent Belgica Trough Mouth Fan in the southern Bellingshausen Sea (Pacific sector of the Southern Ocean) mark the location of a major outlet for the West Antarctic Ice Sheet during the Late Quaternary. The drainage basin of an ice stream that advanced through Belgica Trough across the shelf during the last glacial period comprised an area exceeding 200,000 km**2 in the West Antarctic hinterland. Previous studies, mainly based on marine-geophysical data from the continental shelf and slope, focused on the bathymetry and seafloor bedforms, and the reconstruction of associated depositional processes and ice- drainage patterns. In contrast, there was only sparse information from seabed sediments recovered by coring. In this paper, we present lithological and clay mineralogical data of 21 sediment cores collected from the shelf and slope of the southern Bellingshausen Sea. Most cores recovered three lithological units, which can be attributed to facies types deposited under glacial, transitional and seasonally open-marine conditions. The clay mineral assemblages document coinciding changes in provenance. The relationship between the clay mineral assemblages in the subglacial and proglacial sediments on the shelf and the glacial diamictons on the slope confirms that a grounded ice stream advanced through Belgica Trough to the shelf break during the past, thereby depositing detritus eroded in the West Antarctic hinterland as soft till on the shelf and as glaciogenic debris flows on the slope. The thinness of the transitional and seasonally open-marine sediments in the cores suggests that this ice advance occurred during the last glacial period. Clay mineralogical, acoustic sub-bottom and seismic data furthermore demonstrate that the palaeo-ice stream probably reworked old sedimentary strata, including older tills, on the shelf and incorporated this debris into its till bed. The geographical heterogeneity of the clay mineral assemblages in the sub- and proglacial diamictons and gravelly ...