Abstract An integrated, multidisciplinary study of the tectonic framework, sedimentation, and petroleum systems in the Sergipe–Alagoas Basin was carried out. The methodology was based on regional integration of geologic and geophysical data, particularly seismic reflection and potential field data (gravity and magnetics), results of exploratory drilling, paleontologic and paleoenvironmental analysis of the sedimentary succession, and geochemical data from oils and source rocks. The main topics addressed were the tectono-stratigraphic evolution of the sedimentary basins in northeastern Brazil, the crustal architecture of the Sergipe–Alagoas Basin, and the petroleum systems both onshore and offshore. Results of this study indicate that major synrift troughs are located in the proximal regions and are characterized by negative Bouguer anomalies. The proximal grabens are controlled by comparatively small synthetic and antithetic normal faults, while major rift blocks are controlled by crustal faults that dip seaward. These master faults cut through most of the crust and detach onto lower crustal horizons or even the seismic Moho. Deep-water rift blocks were affected by regional erosional episodes. The transition to pure oceanic crust is marked by wedges of seaward-dipping reflectors and igneous plugs. Some possible salt diapirs are located near the crustal limit. The petroleum systems for this basin include good source rocks in the transitional (evaporitic) and rift-phase sequences. Hydrocarbon generation and migration was effective from Late Cretaceous time onward. Exploratory plays include structural traps associated with synrift and postrift structures, as well as stratigraphic traps associated with deep-water turbidites.

Abstract The continental margin basins of Brazil and west Africa share very similar tectonostratigraphic units because of their proximity in Late Jurassic–Early Cretaceous time. As a result of the paleogeographic ties between the South American and the African plates, the oil habitat of the marginal basins of both continents can often be correlated. To better understand the petroleum systems along the South Atlantic margins, geochemical results obtained from the analysis of 290 oils from the major Brazilian and west African coastal basins were statistically evaluated to establish genetic relationships, distinguish source paleoenvironments and age, and identify different petroleum systems. A number of general oil families composed of genetically related oils were identified, several of which contain oils from both sides of the margin. Areas where oils of mixed provenance occur are also identified. Presalt (Neocomian–Aptian) lacustrine oils can be separated into at least three distinct families and are present in the Congo, Lower Congo, and Benguela Basins of west Africa and the Recôncavo, Campos, Potiguar, Ceará, and Bahia Sul Basins of Brazil. Genetically related oils may be present in the Campos Basin and offshore central Angola and in the Recôncavo Basin and central Gabon and northern Angola. Postsalt (Upper Cretaceous–Tertiary) marine oils are present in the Ivory Coast and the northern Gabon, Lower Congo, Kwanza, and Benguela Basins of west Africa and the Santos, Espírito Santo, and Sergipe–Alagoas Basins of Brazil. Oil mixing may have occurred in the Ivory Coast, Lower Congo, and Kwanza. Genetically related oils may occur in the Sergipe–Alagoas Basin and from northern Gabon. Oils from Nigeria, Benin, Equatorial Guinea, Cameroon, offshore northern Angola, and the Foz do Amazonas Basin of northern Brazil originated from Tertiary source rocks primarily composed of terrigenous organic matter deposited in fluvial deltaic or nearshore marine environments.