University of North Carolina, United States

A new drilling project on the Coulman High (77.46 degrees S; 171.23 degrees to 171.68 degrees E) is under development for the ANDRILL (ANtarctic geological DRILLing) Program. The proposed sites will target lower Miocene and older Paleogene strata in the western Ross Sea in order to investigate: (1) evolution and stability of the cryosphere, (2) warm "greenhouse" periods in the Early Tertiary, (3) orbital variability and controls on Oligocene and Miocene climate and cryosphere, and (4) tectonics within the West Antarctic Rift System and the Transantarctic Mountains. Two drill sites are located in the C-19 iceberg calving site on the Coulman High between Victoria Land Basin and Central Trough. The C-19 area is characterized by basement and syn-rift Paleogene strata faulted into N-S half grabens. This section is overlain by undeformed upper Oligocene and Miocene sediments above a widespread angular unconformity. Regional seismic correlation to drillcores in the Eastern Basin (DSDP 270 and 272), Central Trough (DSDP 273), and Victoria Land Basin (CRP 1, 2, 3 and AND-1B and AND-2B) provide stratigraphic context for the target interval. Proposed sites are on a seismic profile closest to the ice shelf front (1A0); this line has since been covered by the advancing ice shelf that is moving north at a rate of 740 m/year. The water depth here is 834-871 m and the Ross Ice Shelf is 229-251 m-thick. A site survey was conducted at the front of the ice shelf in 2003 under the premise that the advancing ice sheet will in time cover the survey lines, thereby allowing drilling into the sea bed from the ice shelf. Single and multichannel seismic reflection profiles were collected, along with gravity, magnetics and swath bathymetry on a grid with E-W lines spaced at 2-5 km, and three N-S tie-lines spaced at 10 km.