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Department of Geological Sciences, University of Durham, Science Laboratories, South Road, Durham DH1 3LE, England
The Barbados Ridge Complex is the wide accretionary sediment pile associated with the Lesser Antilles island arc. Its width is so great (>200 km) that a trench no longer exists on the oceanward side of it. This development is a product of the age of the system (>50 Ma) and the thickness of sediment on the ocean floor (0.8 km in the north, >4 km in the south). The northward decrease in elevation of the sediment pile and the variation in the style of initial deformation at the leading edge of the pile are related to the northward change in sediment thickness and type. The region in which deformation is prevalent has a westward limit just west of the axis of the minimum negative Bouguer gravity anomaly. In the south the axis of this minimum is coincident with the Barbados Ridge (an outer ‘sedimentary arc’). The deformed rocks of the accretionary pile are overlain by later sediments, which show varying degrees of deformation, and often occupy small basins.
In the northern part of the complex, the relief and structure of the accretionary pile are complicated by ridges and troughs running east-west across the general trend of structures. These appear to be related to variations in the relief of the subducted oceanic basement.
