Leg 178 Antarctic Peninsula

Leg 178 will drill eight sites off the Pacific margin of the Antarctic Peninsula to provide a highresolution record of Antarctic continental climate over the past 6-10 m.y. and a direct check on the presumed glacio-eustatic origin of global sea-level change over the same period. Moreover, it is an essential preliminary to the more difficult task of extracting the complete Cenozoic record of Antarctic glacial history that will be obtained by drilling on the East Antarctic margin. The glacial prograded wedges of the Antarctic Peninsula margin are particularly well-developed, and their glacial record is well-preserved, because of the margin's tectonic youth, high snowfall rates, small-reservoir proximal glacial regime, and underlying 2-D geometry. Associated terrigenous hemipelagic drifts on the adjacent continental rise contain a continuous, high-resolution record of continental climate that will act as a reference section for the topset and foreset records of the shelf. International collaboration through the Antarctic Offshore Seismic Stratigraphy initiative has made extensive data sets available for the planning of a drilling campaign. Site locations strike a balance between the greater density and diversity of data in the northeast and the greater time ...Leg 178 Antarctic Peninsula... separation between tectonic and glacial control of sedimentation in the southwest. The sites aim to sample sedimentation over the last 10 m.y. in all three depositional environments (shelf topsets and foresets, and rise drifts). This conservative, overlapping sampling strategy allows comparison of depositional environments before attempting to sample the longer and more complex history of East Antarctic glaciation. Inshore paleoproductivity in Palmer Deep (companion Proposal 502) seems representative of regional climate, so that this section can be used to compare decadal and millennial-scale variability with that of low-latitude regions and recorded ice cores.