Testing the stratigraphic and paleoenvironmental resolution of sediment drifts off West Antarctica for IODP drilling

There is intense scientific and public interest in the potential response of the Antarctic Peninsula and West Antarctica ice sheets to global warming. Recent observations suggest that this region is undergoing rapid changes including warming, ice-shelf disintegration, ice-sheet thinning and retreat. These recent changes need to be considered in a longer geological context by studying marine sediments proximal to the West Antarctic and Antarctic Peninsula Ice-Sheets. Toward this end, we have submitted and IODP proposal, currently awaiting scheduling, to drill a serie of sites on sediment drifts located in the Bellinghausen Sea (Pacific Ocean). Imprecise chronological control, due in large part to lack of foraminiferal carbonate for isotopic analysis, has stymied paleoceanographic interpretations of sediment cores from the Southern ocean. In preparation for the anticipated IODP expedition, we propose a 'proof-of-concept' study to apply the main paleoceanographic and stratigraphic methods to be employed in the study of the long sequences to be recovered by IODP. We will study piston core PC466 taken at one of the proposed IODP Sites (Pen-1), It was recovered at a water depth of 2400m on a sediment drift on the continental rise in the Bellinghausen Sea (64S, 69W ) by the British Antarctic Survey on RRS James Clark Ross. This short sedimentary record of 10.5 meters spans the last glacial period (~70,000 years) with high sedimentation rates and exhibiting distinct millennial-scale variability in both elemental composition (XRF) and magnetic susceptibility. Our goals for core PC-466 are three-fold. 1) Develop an accurate age model that can be used for stratigraphic correlation to other marine sediment cores and polar ice cores in both hemispheres. 2) Study the advance and retreat of ice sheets using ice-rafted detritus. 3) Reconstruct surface water conditions (temperature, salinity, carbonate-ion concentration, and sea ice). If we are successful in demonstrating that it is possible to apply traditional stratigraphic and paleoceanographic tools to the last glacial period of core PC-466, (a time period that paleoclimatologists and paleoceanographers know best), then we can be reasonably confident that such approaches will work for thousands of meters of record envisaged by proposal-732 and covering the last several million years.