Models for the Cenozoic evolution of the East Antarctic Ice Sheet (EAIS) predict that, during post-late Eocene cooling local glaciers and ice caps nucleated on several highlands of the East Antarctic craton, including the proto-Transantarctic Mountains. These ice caps expanded and then merged during major Neogene cooling events. Significant controversy has however centred on the stability or dynamism of the EAIS during warm periods in the Neogene. This debate remains highly timely since predictions of the response of the EAIS to global warming could utilise its past response as a template for its long-term future evolution.
One of the key areas to assess the past, present and future stability of the EAIS is the Wilkes Subglacial Basin (WSB), in the backside of the Transantarctic Mountains. Dynamists for the EAIS predict that significant deglaciation occurred here perhaps as recently as the Pliocene, allowing for major marine incursion into the WSB. Conversely stabilists have argued that since at least 14 Ma there has been a relatively stable ice sheet.
A major collaborative UK-Italian aerogeophysical survey was flown over the WSB to provide new boundary conditions for the EAIS. Over 60,000 line km of new data were collected, including airborne radar, aeromagnetic and airborne gravity.
Our new-sub-ice topography significantly changes the previous view of the WSB as a broad shallow depression. Deep subglacial trenches flanked by mountain blocks and plateau-like features are now imaged. These tectonically controlled trenches remain well below sea-level even after isostastic rebound following glacial removal. The presence of major marine basins is however unlikely to occur in the southern sector of the WSB. We infer that these basins act and have acted as a major driver for enhanced glacial flow for this part of the EAIS, much like the deep basins underlying several highly dynamic ice streams of the West Antarctic Ice Sheet.
The subglacial topography and location of sedimentary basins derived from the airborne geophysical datasets forms a boundary condition, which we input into new coupled-ice sheet\paleoclimate models to re-assess the highly contentious stability of this part of the EAIS.
