The Recôncavo-Tucano-Jatobá Rift and Associated Atlantic Continental Margin Basins

Abstract

During the opening of the South Atlantic, in the Lower Cretaceous, the Recôncavo-Tucano-Jatobáaborted rift, together with the Camamu-Almada and Jacuípe continental margin basins, developed on the São Francisco cratonic cold lithosphere. This tectonic event finally dismembered the São Francisco-Congo cratonic bridge. The rifting tectonics reactivated Precambrian fabrics of the São Francisco Craton (the Paleoproterozoic Salvador-Itabuna-Curaçábelt), as well as the Neoproterozoic Araçuaíand Sergipano belts. The pre-existing basement structures governed the nucleation of the new rift zones with the generation of intra-basin transfer zones, master listric fault systems, horsts, grabens/hemi-grabens. The listric (crustal scale) master fault systems were able to accommodate a large crustal extension decoupled from the lithospheric thinning, thus preventing magmatic activity in the Recôncavo, Camamu and Almada basins. During the rift stage large wedges of coarse siliciclastic sediments (fluvial and lacustrine) accumulated along syn-sedimentary master faults systems. The syn-rift lacustrine sediments are the most prolific source rocks and responsible for most of the oil produced in the Brazilian passive margin basins. The post-rift evaporite deposits were recorded in both Camamu and Almada basins but are absent in Jacuípe basin. The drift stage sediments display a similar evolution in Jacuípe, Camamu and Almada basins, initiating the cycle with platform carbonates, from Albian to Turonian, evolving later into open marine deposits.