Abstract

Atlantic sedimentary basins are classified into 3 types: (1) tensional rift basins (simple elongate basins and fracture zone end basins), (2) sheared margin basins (fracture zone parallel and fracture ridge dammed basins), and (3) taphrogenic basins. During the early phase of ocean opening, wrench tectonics occur ams offset continential margins, producing splay faulting relative to some transform directions; this influences the formation of fracture zones end and fracture zone parallel basins. Dammed basins develop against fracture zone ridges along large offset sheared margins. In taphrogenic basins of southern S America extant fracture zones follow Palaeozoic lines of weakness across the continent. Basement structures influence the location of some transform directions, particularly in the equatorial Atlantic, and there is some evidence to suggest a link between changes in subsidence rates and the shift in location of poles of opening on sedimentation rates. The asymmetry of basin development on opposing sides of the Atlantic is partially ascribed to the grain of the coastal geology and partly to differential subsidence rates caused by anomalous or asymmetric development of the adjacent ocean floor.

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