Parallel sets of Late Triassic to Early Jurassic diabase (dolerite) dikes in eastern North America, West Africa, and northeastern South America form a radial pattern if the continents are reassembled into their relative positions in Triassic time. The pattern is roughly convergent on the Blake plateau, the Bahama platform, and the western Senegal basin. The dike pattern can be interpreted as being parallel to lines of tension in a net of principal stress trajectories. This net describes a stress field imposed on the continental crust by movements in the upper mantle at the onset of North Atlantic sea-floor spreading.

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