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Abstract

Sedimentary sequences of the continental shelf of the eastern Amundsen Sea Embayment in West Antarctica represent records of past outlet glaciers and ice streams. The former flow of ice streams was channelled through glacial troughs, which now form large bathymetric depressions. We therefore selected one of the largest troughs, the Abbot glacial trough in the outer shelf, to analyse its glacial depositional and erosional history, based on horizon-stratigraphy derived from seismic data. Several basement highs channellized the delivery of sediment and controlled the grounded ice sheet in early glacial periods. Both pre-glacial and full glacial seismic facies were identified. Glacially transported and deposited sediments extended the shelf break by 75 km from the pre-glacial shelf-edge. The main Abbot glacial trough contains sediment from confluent ice flows of the Pine Island/Thwaites, Cosgrove and Abbot Glacier systems, as well as smaller contributions from local ice streams emanating from Thurston Island. Sherman Island of Peacock Sound played an important role in the dynamics of the Abbot Glacier by dividing the ice flow into two ice streams, which interfered with the main glacial sediment transport paths from the south. This study contributes to an understanding of the formation of the Amundsen Sea shelf and the extent of past ice sheet advances.

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