West Antarctic Ice Sheet dynamics between Ross Sea and Amundsen Sea embayments from seismic records and drill data (IODP Expeditions 379 and 374)

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The submarine-based West Antarctic Ice Sheet is suspected to be highly sensitive to climate changes, in particular to in periods of increasing global atmospheric temperatures. The Amundsen Sea sector of the WAIS is in particular vulnerable, because of currently observed incursions of warm Circumpolar Deep Water and ongoing subglacial, ocean-driven melt processes. These observations and the necessity to address paleo-ice sheet constraints for better future sea-level projections have made both the Ross Sea Embayment and the Amundsen Sea Embayment destinations of the two consecutive IODP Expeditions 374 (early 2018) and 379 (early 2019). Both regions are connected via a continuous seismic transect that will be supplemented with additional seismic profiles on the continental rise to be collected during a Russian expedition in early 2019. The seismic profiles will establish a differential and detailed comparison between the sequence stratigraphies of the Amundsen Sea and Ross Sea. In a collaborative effort with the Science Teams of both IODP expeditions and the Russian partners, we plan to analyse the new seismic data, integrate them with pre-existing seismic profiles and perform a thorough and detailed study on the seismic-stratigraphic sequences, units and horizons across the region between the two embayments. The seismic network will be linked to the IODP 374 and 379 drill sites via a careful seismic to core-log integration which will be conducted using the drill core records, physical property data and downhole logging data. Generated synthetic seismograms will be used to compare with seismic profile records at these sites. A trans-regional stratigraphic age and sedimentary compositional model across the Amundsen Sea and Ross Sea sectors is the aim of this first work phase. This will include the development of pre-glacial and glacially dominated sediment transport/deposition models in order to decipher and understand the transitional change-over phase from the greenhouse to the icehouse environment. In the second synthesis phase, the glacially dominated sedimentation processes will be translated to describe flow dynamical patterns of the WAIS in the Amundsen Sea and Ross Sea regions. The sedimentary model will show if and how the past glacial outflow characteristics of the WAIS has changed between Amundsen Sea and Ross Sea sectors.