Ocean Drilling Program, United States

Site 1166 is situated on the southwestern flank of Four Ladies Bank, approximately 40 km southwest of Site 742 in the zone of iceberg-scoured seabed. This site was chosen during Leg 1888 after pack ice prevented access to preferred drill sites in western Prydz Bay. Site 1166 lies close to shotpoint 2050 on seismic line BMR 33-23P3. The expected section consists of 150- to 200-m-thick horizontally bedded glacigene diamictons of late Miocene to Pleistocene age, unconformably overlying about 150-m-thick Paleogene-age sediment, which in turn overlies Early Cretaceous-age nonmarine sediments. The seismic line through Site 1166 shows three erosion surfaces. The uppermost is the base of the upper horizontal sequence and truncates underlying units at a low angle. The second is an undulating surface in the probable Paleogene section that displays pronouned channeling toward north of the site. The third surface delineates the top of the Lower Cretaceous sediments of unit PS.2B that were cored at Site 741. Line BMR 33-23P3 does not show truncation of underlying reflectors at the top of unit PS.2B near Site 1166; however, low-angle truncations can be seen on seismic lines from other parts of the basin.