South Atlantic volcanic margins

The Early Cretaceous South Atlantic continental break-up and initial sea-floor spreading were accompanied by large-scale, transient volcanism emplacing the Parana-Etendeka continental flood basalts and voluminous extrusive constructions on the conjugate margins south of the Torres Arch-Abutment Plateau. On the North Namibia margin we interpret four main tectono-magmatic crustal units: (1) oceanic crust; (2) thickened oceanic crust covered by huge seaward-dipping wedges; (3) a c. 150 km wide break-up related rift zone partly covered by the dipping wedges; and (4) thicker continental crust, partly deformed by Palaeozoic extension, east of the Early Cretaceous rift. Similar settings also characterize other South Atlantic margin segments. We infer an up to 300 km wide and 2400 km long rift zone representing lithospheric extension leading to breakup and formation of the South Atlantic volcanic margins. Comparison with other volcanic margins demonstrates, in spite of local and regional differences, gross similarities in tectono-magmatic style, crustal units and dimensions.