Grounding-Zone Wedges, Till Sheets and Sediment Fluxes in Anvers-Hugo Trough: A Detailed Record of Ice-Stream Retreat Behaviour on the Western Antarctic Peninsula

During the last glacial (~23-19 kyrs BP), the Anvers-Hugo Trough was the drainage pathway for a major palaeo-ice stream of the Antarctic Peninsula Ice Sheet. Here, we integrate a series of seismic and acoustic profiles that have variable vertical resolution with newly published chronological data over glacial landforms in the trough to investigate the deglacial dynamics of the ice stream. Three areas in the trough host grounding-zone wedges - thought to represent pauses in grounding-line retreat. These landforms are similar in scale but have different internal architectures ranging from single wedges to more complex stacked forms. New chronological information from marine sediment cores indicates rapid retreat from the outer to middle shelf between 16.3 and 15.7 kyrs BP when two wedges were formed. The southernmost of these wedges has a complex, stacked architecture suggesting multiple phases of wedge-building, perhaps during a longer phase of grounding-line stagnation. Together, the seismic stratigraphy and core chronology allow us to infer the subglacial sediment fluxes that produced the wedges in each location. Unusually for acoustic sub-bottom profiler data on the Antarctic continental shelf, we are also able to identify megascale-glacial lineations (MSGLs) and other streamlined landforms in the trough at various size scales formed on the surfaces of multiple till sheets at and just below the seabed surface. Based on the volumes of subglacial sediments in the wedges and in the till sheets, we consider the likely delivery rates of subglacial detritus by the Anvers-Hugo palaeo-ice stream alongside inferred flux rates from modern Antarctic ice streams as well as other Arctic and Antarctic palaeo-ice streams.