Geomorphological record of East Antarctic Ice Sheet dynamics in front of Vanderford Glacier

From instrumental observations, we know that the East Antarctic Ice Sheet (EAIS) has experienced mass loss over recent decades, with a higher potential for climate change-induced ice loss than previously assumed. While instrumental data only allow for reconstructing high-latitude ice-sheet dynamics over some decades, little is known about the long-term EAIS development over geological timescales. One possibility to overcome this lack of data is to study the geomorphological record imprinted on the Antarctic continental shelf. Here, we visualize the paleo-ice sheet bed on the Mawson Sea shelf with a focus on the shelf offshore Vanderford Glacier – EAIS’s fastest-retreating glacier forced by increasing intrusions of modified Circumpolar Deep Water. The study uses multibeam bathymetry and sediment echosounder data collected on the continental shelf in front of the Vanderford Glacier terminus during RV Polarstern and RSV Nuyina expeditions in 2024 and 2022 respectively.  A large assemblage of subglacial bedforms was imaged revealing past hydrological and glacial conditions at the former ice sheet bed. An over-deepened glacial trough system right in front of the modern glacier terminus suggests intense past meltwater discharge beneath the Vanderford glacier, possibly reactivated during several glacial cycles. Further seawards, a giant grounding-zone wedge records past subglacial sediment accumulation at the convergence zone of fast-flowing ice streams from various glaciers. The presented glacial landform assemblage reveals a major paleo-ice stream system including corridors of fast-flowing ice, distinct regions of ice flow acceleration, and inter-ice stream regions characterized by slowly moving or even stagnant ice masses. Our new geomorphological data from Vincennes Bay provides crucial information on the EAIS’s past behaviour in a region that currently changes rapidly. As it is directly situated seawards of the vast Aurora Subglacial Basin, it will allow for constraining regional ice sheet and oceanographic models more reliably.