| The Sergipe-Alagoas Basin is located along the northeastern coast of Brazil. The sediments of the basin were deposited during three major tectonic episodes: pre-rift, rift and post-rift phases. These tectonic phases controlled the infilling of the major depositional systems. Rifting in the basin initiated in the Early Cretaceous, with the separation of Africa and South America. In the Neocomian, continental-lacustrine conditions prevailed. During the Aptian, evaporitic basins developed with the onset of restricted marine conditions. Finally, from Albian to the present, open marine conditions existed.;Two major fault systems are present in the basin: (1) N to NNE-trending faults, developed during the Neocomian rift phase, are characterized by a listric shape with growth of strata towards the fault planes; and (2) ENE-trending stike-slip faults which connected the N to NNE-trending fault system during the early rift stages (transfer faults). Later, dip-slip displacement predominated along the ENE-fault system. Growth faults and salt tectonics started to develop during the Aptian with trends that follow the previous fault systems.;Seismic profiles show that some N to NNE-trending listric faults have a very low angle of dip, and intrabasement fault planes appear as eastward-dipping reflections. Intrabasement reflections are interpreted as the seismic response to rift-related detachment faults. Neocomian strata and the upper part of the basement in the hanging wall of the detachment surfaces are generally tilted westward in a half graben configuration, suggesting that the hanging wall rotated during rifting, along intrabasement detachment surfaces. These features demonstrate the interaction between strike-slip and extensional tectonics for the area during the rifting of northeastern Brazil. |
