Description: The landforms and sediments preserved on the Yermak Plateau (Figs 1–3) provide information on the glacial history and past dynamics of the northwestern-most sector of the Eurasian Ice Sheet (Dowdeswell et al. 2010; Gebhardt et al. 2011), as well as the exchange of ice and water between the North Atlantic and the Arctic Ocean via Fram Strait (Fig. 1a) (Jakobsson et al. 2010). Early ideas about Quaternary ice cover in the Arctic Ocean pro- posed the existence of a circum-Arctic ice shelf prior to the last gla- ciation (e.g. Mercer 1970). More recent work suggested that the major glaciations since the interglacial period of marine oxygen isotope stage (MIS) 5.5 did not extend beyond the Eurasian conti- nental shelf edges. However, geophysical data reveal that ice extended across the Yermak Plateau prior to MIS 5.5 during the particularly extensive glaciation in MIS 6 (Dowdeswell et al. 2010; Jakobsson et al. 2010). By contrast, the presence of a grounding-zone complex beyond NW Spitsbergen (Fig. 3) implies that grounded ice did not extend onto the Yermak Plateau during the Last Glacial Maximum (LGM) (Ottesen & Dowdeswell 2009).

Description: 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 Antarctic margin paleoceanography 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 the fact that composite sections are incomplete and lack of precise chronological control. A new drilling proposal (732-Full2) has been scientifically approved and is with the JOIDES Resolution Facilities Board of the International Ocean Discovery Program 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 over the proposed sites and adjacent working areas. The new 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, paleo-ice-sheet dynamics and paleoceanographic processes. Through further analyses of seismic and other geophysical data, in combination with marine sediment cores retrieved from the proposed sites, we aim to provide insight into polar margin sediment delivery, Antarctic ice-sheet history and stability, and Antarctic margin paleoceanography. 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.

Description: Basal hydrological systems play an important role in controlling the dynamic behaviour of ice streams. Data showing their morphology and relationship to geological substrates beneath modern ice streams are, however, sparse and difficult to collect. We present new multibeam bathymetry data that make the Anvers-Hugo Trough west of the Antarctic Peninsula the most completely surveyed palaeo-ice stream pathway in Antarctica. The data reveal a diverse range of landforms, including streamlined features where there was fast flow in the palaeo-ice stream, channels eroded by flow of subglacial water, and compelling evidence of palaeo-ice stream shear margin locations. We interpret landforms as indicating that subglacial water availability played an important role in facilitating ice stream flow and controlling shear margin positions. Water was likely supplied to the ice stream bed episodically as a result of outbursts from a subglacial lake located in the Palmer Deep basin on the inner continental shelf. These interpretations have implications for controls on the onset of fast ice flow, the dynamic behaviour of palaeo-ice streams on the Antarctic continental shelf, and potentially also for behaviour of modern ice streams.

Description: 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.