Structure and Origin of Three Continental-Margin Plateaus, Northeastern Brazil

Abstract

The narrow continental terrace of northeastern Brazil is marked by three plateaus, each 30 to 70 km wide. Preliminary geophysical and dredge data indicate that all three lie along east-west trends connecting oceanic fracture zones and continental lineaments and/or areas of postrifting volcanism and tectonism. Although the Pernambuco Plateau is flanked by prominent basement highs (presumably partly related to oceanic fracture zones), both it and the Rio Grande do Norte Plateau overlie stretched continental crust. In contrast, the Ceara Plateau is a limestone-capped seamount on the western end of the Fernando de Noronha Ridge, and may be as young as 1 to 30 m.y.