Abstract
The stability of the West Antarctic Ice Sheet is threatened by the incursion of warm Circumpolar Deepwater which flows southwards via cross-shelf troughs towards the coast there melting ice shelves. However, the onset of this oceanic forcing on the development and evolution of the West Antarctic Ice Sheet remains poorly understood. Here, we use single- and multichannel seismic reflection profiles to investigate the architecture of a sediment body on the shelf of the Amundsen Sea Embayment. We estimate the formation age of this sediment body to be around the Eocene-Oligocene Transition and find that it possesses the geometry and depositional pattern of a plastered sediment drift. We suggest this indicates a southward inflow of deep water which probably supplied heat and, thus, prevented West Antarctic Ice Sheet advance beyond the coast at this time. We conclude that the West Antarctic Ice Sheet has likely experienced a strong oceanic influence on its dynamics since its initial formation.
Highlights
The stability of the West Antarctic Ice Sheet is threatened by the incursion of warm Circumpolar Deepwater which flows southwards via cross-shelf troughs towards the coast there melting ice shelves
Modelling studies simulate past West Antarctic Ice Sheet (WAIS) collapses driven primarily by warm water incursion, e.g., during the Pliocene and some Quaternary interglacial periods[10,11], there is little observational evidence recording the effects of oceanographic circulation on the longer term history of the ice sheet
Seismic reflection data collected in Pine Island Trough (PIT) reveal an asymmetric sediment body at the eastern flank of the trough
Summary
The stability of the West Antarctic Ice Sheet is threatened by the incursion of warm Circumpolar Deepwater which flows southwards via cross-shelf troughs towards the coast there melting ice shelves. We estimate the formation age of this sediment body to be around the Eocene-Oligocene Transition and find that it possesses the geometry and depositional pattern of a plastered sediment drift We suggest this indicates a southward inflow of deep water which probably supplied heat and, prevented West Antarctic Ice Sheet advance beyond the coast at this time. Modelling studies simulate past WAIS collapses driven primarily by warm water incursion, e.g., during the Pliocene and some Quaternary interglacial periods[10,11], there is little observational evidence recording the effects of oceanographic circulation on the longer term history of the ice sheet This applies to its initial advance onto the continental shelf. We present seismic reflection data combined with age information from shallow seabed drill cores from the ASE shelf to investigate potential palaeo-intrusions of deep water at the EOT by analysing the architecture of a sediment body identified in seismic profiles
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