This study focuses on several globally important, crustforming orogenic processes that have been active during the complex tectonic history of the Pacific margin of Antarctica. This award supports a comprehensive geophysical survey (i.e., MCS, gravity, magnetics, sonobuoys and multi- beam bathymetry) of two parts of the Antarctic Peninsula to illuminate the role of the South Shetland Islands-Bransfield Trough region as a modern analog of Andean orogenic processes and as a specific step toward tectonic reconnaissance of the less accessible and therefore more poorly known parts of the West Antarctic margin bordering the Bellingshausen and Amundsen seas. By integrating the marine data with onshore geologic observations and kinematic plate motion histories, this investigation should be able to make real progress towards increased understanding of the following processes: Andean-type orogenesis; continental lithosphere extension in a convergent continental margin setting; ridge crest subduction; and interaction of large- offset fracture zones with convergent margins, including the uplift of subduction complexes. The study will provide impetus for the U.S. Antarctic Geoscience Initiative by undertaking the most ambitious Antarctic marine geophysical study yet carried out by any nation.
