Ice-core-dated englacial stratigraphy across upper Wilkes Subglacial Basin, East Antarctica: Stratigraphic connections and implications for ice-sheet behaviour

Wilkes Subglacial Basin (WSB), is one of several marine basins in East Antarctica, and has been highlighted as a potential key area of ice-sheet vulnerability to future climate-induced ice loss. Recent studies have shown both contemporary acceleration and thinning of outlet glaciers in the area, and found indications of extensive deglaciation and/or grounding line retreat of the ice sheet in the basin during past interglacials. Here, we use the englacial stratigraphy to investigate the glacial history of WSB back to the Last Interglacial (~130 – 115 ka). Using the WISE-ISODYN survey, a UK/Italian airborne radio-echo sounding collaboration survey from 2005/06, we trace eight internal reflection horizons (IRH) across WSB, and date them at intersections with Talos Dome and EPICA Dome C ice cores. These IRHs span ages from 13.1 ± 0.5 to 90.3 ± 2.3 ka, with an older IRH of 122.5 ± 2.0 ka traced across Dome C Plateau. We find that ~300 km upstream of the WSB grounding line, ~ 20 % of the ice lies below, and is hence older than, 90.3 ± 2.3 ka. This suggests that the ice was present across this region throughout the Last Interglacial. Furthermore, we highlight several zones of interest with regard to ice-sheet behaviour across the basin, including zones of changing ice flow, areas of relatively old ice, and areas where we find potential for high geothermal heat flow. The dataset generated with this research furthermore contributes to the wider objective of mapping Antarctica-wide englacial stratigraphy, and will provide useful observational constraints to studies modelling the past and future growth and decay of the East Antarctic Ice Sheet in Wilkes Subglacial Basin.