Northeastern Brazil and the final separation of south America and Africa

New evidence has been added to support the old but practically discarded idea that the separation of the two continents, South America and Africa, was delayed in the middle portion. A land bridge connecting the Brazilian Bulge and Nigeria is postulated to account for the peculiar pattern of the Bouguer gravity and vertical field magnetic anomalies on the Brazilian side, and for the large area of overlap on the map of Bullard's fit. Moreover, integrated sedimentological, paleontological and oceanographical evidence seems to confirm the model, due to the following facts: (1) phosphate and limestone deposits pointing to strong upwelling against a sill; (2) narrow faunal links between Brazil and Africa until the Late Cretaceous; (3) no exchange of planktonic foraminifera between the North and South Atlantic until the end of the Maastrichtian; (4) shallow-water deposits of late Cretaceous age now found at considerable depths; (5) no evidence for deep bottom-water circulation until the Early Tertiary. Detailed analysis of all available data converges on the existence of a land bridge between the two continents until the end of the Cretaceous.