The USAC Aeroseophysical Survey of the Basins Surrounding the Antarctic Peninsula

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This project is the final year of a three-year airborne geophysical survey to obtain magnetic and gravimetric data within the continental margins and basins surrounding the Antarctic Peninsula. The project is a joint effort between the Lamont-Doherty Geological Observatory and the Naval Research Laboratory, which will provide an instrumented P-3 aircraft in support of the project. The present project is based on prior work in the 1985/86 and the 1986/87 austral summer seasons, in which about 150,000 km of geophysical data was obtained in a series of flights covering much of the previously unsurveyed western Weddell Sea Basin and the Bransfield Strait. Preliminary results from that field work have defined a fossil subduction zone bordering the Powell Basin, a magnetic anomaly typical of an ocean-continent transition extending from Jurassic volcanic sequences on the Lassiter Coast, and a symmetric anomaly pattern in the Bransfield Strait. The present field work will concentrate on acquiring magnetic data in the Scotia Basin, and carrying out a magnetic and gravity survey of the western Bellingshausen margin. The airborne surveys have been designed to produce an efficient and rapid geomagnetic picture of the peninsular sector and its eastern and western margins. Much of this area is normally covered by ice and is inaccessible to ships, therefore the project will provide data that could not otherwise be obtained. The NRL P-3 is specifically designed to support geophysical research and is an excellent long-range platform for this project. Results from this work will improve our understanding of the relative motions of tectonic plates and the interpretation of the geology of the Antarctic Peninsula, and provide constraints on the time of opening of the Drake Passage and the evolution of southern ocean circulation patterns.