Basement control in Camamu and Almada rift basins

Abstract

The Camamu and Almada basins are located on the coast of Bahia state, between the cities of Salvador and Ilhéus. Basement rocks in these basins are paleoproterozoic and neoproterozoic rocks of the Itabuna-Salvador-Curuça and Araçuaí Orogens. Their structural frameworks left a legacy of kilometer scale fold belts and shear zones that strongly influenced the initiation and evolution of the cretaceous rifting system. Major reactivations were respectively accommodated by the NW-SE, N-S and NE-SW trending shear zones of Salvador, Itabuna and Itaju do Colônia. This work demonstrates these shear zones were probably reactivated as transverse faults, exerting critical influence on the initiation and propagation of the cretaceous rifting. This phenomenon is marked in many different ways in each rift basin. The most important variations are in the depocenter distribution, segmentation, compartmentalization of salt masses and tectonic style.