This award supports an investigation of the early seafloor spreading history of the Marie Byrd Land Margin, Antarctica. This effort will carefully map the magnetic lineations, the gravity anomalies, the topography and, where possible, the seismically determined depth to basement. The study will integrate the tectonic lineations determined from the gravity, bathymetry and seismic information with the magnetic anomalies to construct a new seafloor spreading history of the Marie Byrd Land Margin. The analysis of these new data sets and the resultant seafloor spreading history will be used to address the following questions: (1) Did the early opening of the Pacific-Antarctic Ridge involve an additional plate, the Bellingshausen Plate, or did the ridge undergo very asymmetric, non-orthogonal spreading? (2) With a better refined opening history for the Pacific Antarctic Ridge, what are the implications for relative motions between the tectonic blocks which compromise West Antarctica and for the structure and evolution of the Marie Byrd Land Margin? (3) Can the global plate circuit solution be enhanced by refining the early Tertiary history of Pacific-Antarctic seafloor spreading?
