Wilson OPP 9527394 Jarrard OPP 9527319 Zoback OPP 9527412 Abstract This award supports a collaborative research program to obtain the first age-calibrated stress-field history within the West Antarctic rift system of Antarctica. The opportunity to acquire the stress data is provided by the international drilling program planned at Cape Roberts, which is located along the margin between the uplifted Transantarctic Mountains and the rifted crust of the Victoria Land basin. Information on the paleostress history of the Mesozoic and Cenozoic rift-basin fill will be obtained from the core and downhole logging of natural fractures and faults. To establish the contemporary stress state, the cores will be examined for coring-induced stress fractures and the borehole will be examined via downhole televiewer and dipmeter for any wellbore breakouts and fractures reactivated by the contemporary stress field. The stress data will be analyzed to address questions relevant to the paleo- and neotectonic evolution of the Antarctic plate. The results will contribute to the resolution of outstanding questions such as the cause of the anomalous aseismicity of the continent, the geometry of stresses along the lithospheric boundary between the Transantarctic Mountains and the West Antarctic rift system, and the evolution of the Antarctic intraplate stress field and its relation to rifting episodes associated with Gondwanaland breakup. Contemporary stress data obtained from this program will be added to the global stress data base, and will help to fill the current void in the global stress coverage marked by the Antarctic plate.
