Hillenbrand, Claus-Dieter; Ehrmann, Werner; Larter, Robert D; Benetti, Sara; Dowdeswell, Julian A; Cofaigh, Colm Ó; Graham, Alastair GC; Grobe, Hannes (2009): Clay mineralogy and shear strength of subglacial and glaciomarine sediments in the southern Bellingshausen Sea. doi:10.1594/PANGAEA.711173, Supplement to: Hillenbrand, C-D et al. (2009): Clay mineral provenance of sediments in the southern Bellingshausen Sea reveals drainage changes of the West Antarctic Ice Sheet during the Late Quaternary. Marine Geology, 265(1-2), 1-18, doi:10.1016/j.margeo.2009.06.009
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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 deposits indicates that they were eroded from underlying sedimentary strata of different ages. These strata may have been deposited during either different phases of the last glacial period or different glacial and interglacial periods. Additionally, the clay mineralogical heterogeneity of the soft tills recovered on the shelf suggests that the drainage area of the palaeo-ice stream flowing through Belgica Trough changed through time.
Median Latitude: -71.152776 * Median Longitude: -83.645195 * South-bound Latitude: -73.401667 * West-bound Longitude: -89.735000 * North-bound Latitude: -69.305000 * East-bound Longitude: -72.575000
Date/Time Start: 1994-02-05T01:11:00 * Date/Time End: 2004-02-08T04:21:00
JR104-BC351 (BC351 CORE_NO 351) * Latitude: -70.086700 * Longitude: -86.193300 * Date/Time: 2004-01-28T00:00:00 * Elevation: -1041.0 m * Recovery: 0.34 m * Location: Bellingshausen Sea, upper slope on Trough Mouth Fan (TMF) * Campaign: JR20040123 (JR104) * Basis: James Clark Ross * Device: Box corer (BC) * Comment: smear slide, surface sediment (11.5x22.0x1 cm), 1 core X (1-31.5), 1 core Y (0-30 cmbsf)
JR104-BC356 (BC356 CORE_NO 356) * Latitude: -71.768300 * Longitude: -80.110000 * Date/Time: 2004-01-31T00:00:00 * Elevation: -565.0 m * Recovery: 0.11 m * Location: Bellingshausen Sea, till sheet on shelf N of Smyley Island * Campaign: JR20040123 (JR104) * Basis: James Clark Ross * Device: Box corer (BC) * Comment: surface sediment (11.5x22.0x1 cm), bulk sediment (rest of recovered sediment volume), 2 dropstones with serpulid worms and bryozoa
JR104-BC361 (BC361 CORE_NO 361) * Latitude: -71.993300 * Longitude: -76.553300 * Date/Time: 2004-02-01T00:00:00 * Elevation: -633.0 m * Recovery: 0.37 m * Location: Bellingshausen Sea, till sheet on N side of Ronne Entrance Trough * Campaign: JR20040123 (JR104) * Basis: James Clark Ross * Device: Box corer (BC) * Comment: surface sediment (c. 10x10x1 cm), 1 core X (0-10.5 cmbsf), 1 core Y (0-23 cmbsf)