Sites 1098 and 1099 are located in Palmer Deep on the inner continental shelf southwest of Anvers Island, off the Antarctic Peninsula (Fig. F1). Drilling in Palmer Deep (Sites 1098 and 1099) was aimed at reconstructing the most recent glacial history of the Antarctic Peninsula, through the recovery of a Holocene, and possibly latest Pleistocene, paleoproductivity record representative of regional climate at a decadal and millennial scale. Palmer Deep is a glacially overdeepened basin consisting of three subbasins aligned in an approximately southwest-northeast direction (Fig. F2). These basins contain an ultra high resolution Holocene record of Antarctic Peninsula climate (Leventer et al., 1996).
Site 1099 is located in Basin III, which contains three major acoustic units; the uppermost (~0-70 mbsf; the midbasin reflector) shows similar character to the fill of Basin I (Barker, Camerlenghi, Acton, et al., 1999). Site 1098 was drilled at the southwestern end of Basin I, where sediment fill is draped, contrasting with the overall ponded geometry of the rest of the basin. Each site was assigned a single lithostratigraphic unit (Unit I), and Site 1098 was subsequently subdivided into Subunits IA and IB. Sedimentation in Basin III was recognized by the shipboard party (Barker, Camerlenghi, Acton, et al., 1999) as more affected by mass flow than in Basin I. Additional stratigraphic data derived from piston cores, including radiocarbon dating in Basin III (Kirby et al., in press), suggest that the base of Unit I, as well as the deeper units, may predate the most recent glaciation on the shelf (the last glacial maximum). The seismic units below the midbasin reflectors were therefore considered to be older than the basin-fill unit of Basin I. The basins have some similar depositional environments, but they are also affected by local events and are therefore not directly comparable.