The area west of the Antarctic Peninsula is a key region for studying and understanding the history of glaciation in the southern high latitudes during the Neogene. The area is critical for learning variations in the western Antarctic continental ice sheet, the sea ice cover, the induced eustatic sea level change, and consequences for the global climatic system. Sites 1095, 1096, and 1101 (Fig. F1) were drilled on sediment drifts that form the continental rise to examine the nature and composition of sediments deposited under the influence of the fluctuating Antarctic Peninsula ice sheet. The ice sheet has repeatedly advanced to the shelf edge and subsequently released glacially eroded material on the continental slope and rise (Barker, 1995; Barker et al., 1998, 1999). Mass-wasting processes on the slope are responsible for downslope sediment transport by turbidity currents within a channel system between the drifts (Rebesco et al., 1998). Bottom currents redistribute the sediments, thus leading to the final buildup of drift bodies (Camerlenghi et al., 1997). The high-resolution sedimentary sequences on the continental rise can be used to document the variability of continental glaciation and, therefore, allow us to assess the main factors that control sediment transport and depositional processes during glacial periods and their relationship to glacioeustatic sea level changes.
This research was carried out on material from Site 1095, where coring recovered sediments as old as late Miocene (9.7 Ma). Site 1095 lies in 3840 m of water in a distal position on the northwestern lower flank of Drift 7 (Fig. F2). We measured the grain-size distribution of 530 samples from Holes 1095A, 1095B, and 1095D to obtain a more detailed picture of three controlling factors: (1) the variability and magnitude of turbidites, (2) deep-oceanic currents (contourite currents), and (3) the ice-rafting component since the late Miocene.