Seismic and geomorphic records of Antarctic Ice Sheet evolution in the Ross Sea and controlling factors in its behaviour

Abstract

AbstractA robust collection of seismic and geomorphic data is used to examine the evolution of the Antarctic Ice Sheet within the Ross Sea Embayment. We use geomorphic data to reconstruct Last Glacial Maximum and post-Last Glacial Maximum ice sheet drainage and demonstrate retreat behaviours for the East Antarctic and West Antarctic sectors of the ice sheet. Using this framework, we then use seismic data and chronostratigraphic information from drill cores to reconstruct the long-term evolution of the ice sheet. Early ice sheet evolution during the Late Oligocene was characterized by isolated ice caps on bathymetric highs, followed by an interval of sediment infilling of rift basins and the development of more subdued relief in the eastern Ross Sea than in the western Ross Sea. Both ice sheets have experienced multiple episodes of expansion across the continental shelf since the Middle Miocene, with the frequency increasing during the Plio-Pleistocene. We conclude that seafloor bathymetry has been the principal control on ice sheet palaeodrainage and retreat behaviour since at least the middle Miocene, demonstrated by broad West Antarctic ice streams loosely guided by south to north cross-shelf troughs, whereas East Antarctic ice streams were funnelled through troughs that merge and converge around banks.