SEISMIC AND GLACIAL STRATIGRAPHY OF THE NORTHWESTERN WEDDELL SEA CONTINENTAL SHELF

Previous studies of the stratigraphy of the Northwestern Weddell Sea, along the eastern margin of the Antarctic Peninsula, have been conducted in the James Ross Basin and in the Larsen Basin. High-resolution seismic data acquired during the 2002 field season allows integration of the previous studies and a detailed understanding of the Cenozoic stratigraphy spanning the onset of glaciation though the latest glacial maximum. Initial observations of the seismic lines show two significant unconformities. The lower unconformity represents a major erosional period marking the onset of glaciation. This unconformity may be equivalent to the mid-Miocene unconformity on the Pacific margin of the peninsula. The upper unconformity is most-likely an amalgamated surface representing several glacial advances. This surface forms much of the present-day continental shelf bathymetry. The deposits above this unconformity are characterized by grounding zone wedges and chaotic reflection patterns. Multibeam swath bathymetry data acquired in the northern portion of the study area indicates ice flow to the southeast during the most recent advance of the ice sheet.

The continental shelf offshore of Seymour Island and James Ross Island, in the Northwestern Weddell Sea, has been targeted as the first place for shallow drilling on the Antarctic margin. This area has a seaward dipping succession of strata that are believed to bear an exceptional record of Antarctica’s climate and glacial setting during the past 30 million years. The SHALDRIL group will sample these strata in the near future allowing calibration of the stratigraphic section to that of other areas of Antarctica.