This is a U.S.-French field study in the Central Indian Basin aboard the French research vessel Marion Dufresne. Long (30 to 45 meters) and large-diameter (15cm) piston cores will be obtained along a transect extending from the equator to approximately 15 south. This transect spans several first- order oceanographic and sedimentary transition zones, reflecting the confluence of distal turbidite sedimentation on the lower Ganges fan and biosiliceaous sedimentation associated with the hydrochemical "front" (10 S) and the South Equatorial Current. These cores will extend the Indian Ocean magnetobiostratigraphic type-section from Plio-Pleistocene down into the Middle-Upper Miocene, ca 10Ma. Using this stratigraphic type-section, the study will be able to establish with high precision the chronology of major episodes of biosiliceous and distal turbidite sedimentation in the Central Indian Basin during the Neogene, and the degree of non-synchroneity of radiolarian datum levels.
