The West Antarctic Ice Sheet (WAIS) and Antarctic Peninsula Ice Sheet (APIS) have exhibited significant changes over recent decades but there is still great uncertainty about how rapidly and how far they will retreat in a warmer climate. For example, it remains unclear whether or not the marine-based WAIS “collapsed” during the last interglacial period, resulting in a global sea-level rise contribution of more than 3 m. Previous studies, including Ocean Drilling Program (ODP) Leg 178, have shown that sediment drifts on the continental rise west of the Antarctic Peninsula contain a rich high-resolution archive of Southern Ocean palaeoceanography and APIS history that extends back to at least the Late Miocene. The potential of existing ODP cores from the drifts is, however, compromised by incomplete composite sections and lack of precise chronological control. A proposal for future drilling on the drifts (732-Full2) has been scientifically approved and is with the JOIDES Resolution Facilities Board for scheduling. The main aims of the proposal are to obtain continuous, high-resolution records from sites on sediment drifts off both the Antarctic Peninsula and West Antarctica (southern Bellingshausen Sea) and to achieve good chronological control on them using a range of techniques. We present preliminary results from a recent site survey investigation cruise on RRS James Clark Ross (JR298) that obtained high-resolution multichannel seismic reflection data, piston cores and box cores to bolster this proposal. The new data and cores provide opportunities to improve understanding of the depositional setting, ensure that there is a comprehensive site survey data package to allay any concerns that the Environmental Protection and Safety Panel may raise, and allow testing of some of the hypotheses underpinning the proposal. The new seismic data provide a basis for interpretation of (i) sedimentary processes that operated during the development of the drifts, and (ii) links between depositional systems on the continental rise, palaeo-ice-sheet dynamics and palaeoceanographic processes. Through further analyses of the seismic and other geophysical data, in combination with the marine sediment cores, we aim to provide insight into polar margin sediment delivery, Antarctic ice-sheet history and stability, and Southern Ocean palaeoceanography. Subsequently, the proposed drilling campaign will allow a detailed chronology to be established on extended records that will provide a basis for high-resolution interpretations extending back through the Pliocene.
EPIC Alfred Wegener Institut