RUI: Arc-Continent Interaction and Evolution of the Caribbean-South American Plate Boundary

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This project involves study of multichannel marine seismic profiles to resolve the structural and tectonic history of the southern Lesser Antilles arc and adjacent parts of the continental margin of South America. Objectives of the study are the identification of terrane boundaries based on lateral discordance and change in seismic character (amplitude, coherency, continuity) and velocity of reflectors, and the identification of structures and determination of their timing in layered sequences based on correlation with wells. The ultimate goal is to interpret existing, newly obtained data, leading to an improved understanding of: (1) arc-continent interaction processes leading to the accretionary growth of continents, and (2) the structural and tectonic history of the eastern reach of the Caribbean-South American boundary zone. Two principal models have been proposed for the nature of the plate boundary: (A) a margin-parallel, east-striking strike-slip boundary with large, distributed, right-lateral (easterly) displacement of the southern Lesser Antilles, and (B) an oblique collision zone with small easterly displacement of the southern Lesser Antilles. A broad zone of deformation, perhaps hundereds of kilometers wide, is postulated by both of the plate boundary models. Because such a deformation zone is largely submerged, marine seismic profiles offer the only means besides seismicity and potential field data to study its structure in the offshore. The study may permit discrimination between the two aforementioned models or lead to the development of a new alternative model.