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RABINOWITZ, PHILIP D., TIMOTHY J. G. FRANCIS, JACK G. BALDAUF, and JAMES F. ALLAN, Texas A&M University, Ocean Drilling Program, College Station, TX

ABSTRACT: Ocean Drilling Bordering the South American Continent

The Ocean Drilling Program (ODP) has completed three expeditions bordering South America and is in the planning stages of a further expedition. The first cruise, Leg 110, drilled at six sites on a transect across the structural boundary between the overthrusting Barbados Ridge Complex and Atlantic abyssal plain (Caribbean/Atlantic Plate Boundary) in order to investigate structural, hydrological, and diagenetic effects of the transition from undeformed deep sea sediments to stratally disrupted melange on land. The second cruise, Leg 112, drilled ten sites to investigate the geological and paleoceanographic history of the area between the Peru Trench (which marks the suture between the Nazca and South American Plates) and the Peruvian coast. A third cruise, Leg 1 41, drilled the Chile T iple Junction, which represents the only presently active ridge-trench collision where the overriding plate is composed of continental lithosphere. Leg 141 studied the processes of ridge-crest subduction and the physical properties and geochemistry of gas hydrates in oceanic sediments. A fourth cruise off South America is presently in the planning stage by the international science community. This proposed paleoceanographic transect is on the Ceara Rise off northern Brazil and has a proposed objective, amongst others, of studying the history of deep water flow of the Atlantic during the Cenozoic with an emphasis on the relationships between deep water circulation chemistry and Earth's climate.

This paper focuses on the significant scientific results of the above cruises and discusses future plans off South America.

AAPG Search and Discovery Article #90988©1993 AAPG/SVG International Congress and Exhibition, Caracas, Venezuela, March 14-17, 1993.