The South Atlantic margin developed on Archean stable cratons consisting of hard and resistant rocks and partly on the Neoproterozoic mobile belts composed of less resistant metamorphic rocks.
The Precambrian basement of the Santos Basin is exposed as the Araçuaí Belt along the Brazilian coast, most notably in the inselbergs of Rio de Janeiro, of which Sugarloaf Mountain is the most iconic.
The ancient rocks consist of a Neoproterozoic to Cambrian high-grade metamorphic core of granites and gneisses, formed during the collision of Gondwana in the Pan-African-Brasiliano orogeny.
Basalts similar to the Paraná and Etendeka traps, exposed to the west in the Paraná Basin, have been found underlying the Santos Basin.
The Tristan da Cunha hotspot, known as the Tristan hotspot, is considered the driver behind the formation of these flood basalts.

During the Early Cretaceous, the former continent Gondwana, as southern part of Pangea, starting to break-up, resulting in a sequence of rift basins bordering the present-day South Atlantic.
The Pelotas-Namibia spreading commenced in the Hauterivian, around 133 million years ago and reached the Santos Basin to the north in the Barremian.
Seafloor spreading continued northwards to the Campos Basin in the Early Albian, at approximately 112 Ma.

Five tectonic stages have been identified in the Brazilian basins:
Pre-rift stage - Jurassic to Valanginian
Syn-rift stage - Hauterivian to Late Barremian
Sag stage - Late Barremian to Late Aptian
Post-rift stage - Early to Middle Albian
Drift stage - Late Albian to Holocene
The sag phase in the Santos Basin was characterised by thermal subsidence and generated restricted depocentres with relatively uniform water depths, ranging from 600 to 950 metres (1,970 to 3,120 ft).
The Late Aptian climate was arid with high evaporation rates which triggered hypersaline conditions in these marginal sag basins.
This resulted in the accumulation of thick layers of evaporites along the Brazilian and southwestern African continental margins, a process continuing towards the north later in the Cretaceous.
The deposition of the lowermost 600 metres (2,000 ft) of salt in the Aptian would have taken approximately 20,000 to 30,000 years.
With the continental break-up of the Santos and Campos Basins from the opposite Namibia and Kwanza Basins, oceanic circulation returned during the post-rift stage.
The drift phase since the Late Cretaceous produced a thick sequence of clastic and carbonate deposits.
Differential thermal regimes and sediment loading of these units produced halokinesis; salt movement in the subsurface.
The resulting salt diapirs, listric and thrust faults and various salt-related structures produced several stratigraphic and combined stratigraphic-structural traps for hydrocarbon accumulation in the Brazilian and southwest African offshore.

During the phases of halokinesis, dated to the Albian to Paleocene, several areas of the now deep water distal part of the Santos Basin were exposed to subaerial conditions and suffered erosion.
The distal parts of the basin were affected by E-W to NW-SE oriented shortening, sub-perpendicular to the Brazilian margin.
The South Atlantic margin developed on Archean stable cratons consisting of hard and resistant rocks and partly on the Neoproterozoic mobile belts composed of less resistant metamorphic rocks. The Precambrian basement of the Santos Basin is exposed as the Araçuaí Belt along the Brazilian coast, most notably in the inselbergs of Rio de Janeiro, of which Sugarloaf Mountain is the most iconic. The ancient rocks consist of a Neoproterozoic to Cambrian high-grade metamorphic core of granites and gneisses, formed during the collision of Gondwana in the Pan-African-Brasiliano orogeny. Basalts similar to the Paraná and Etendeka traps, exposed to the west in the Paraná Basin, have been found underlying the Santos Basin. The Tristan da Cunha hotspot, known as the Tristan hotspot, is considered the driver behind the formation of these flood basalts.
During the Early Cretaceous, the former continent Gondwana, as southern part of Pangea, starting to break-up, resulting in a sequence of rift basins bordering the present-day South Atlantic. The Pelotas-Namibia spreading commenced in the Hauterivian, around 133 million years ago and reached the Santos Basin to the north in the Barremian. Seafloor spreading continued northwards to the Campos Basin in the Early Albian, at approximately 112 Ma.
Five tectonic stages have been identified in the Brazilian basins:
Pre-rift stage - Jurassic to Valanginian
Syn-rift stage - Hauterivian to Late Barremian
Sag stage - Late Barremian to Late Aptian
Post-rift stage - Early to Middle Albian
Drift stage - Late Albian to Holocene
The sag phase in the Santos Basin was characterised by thermal subsidence and generated restricted depocentres with relatively uniform water depths, ranging from 600 to 950 metres (1,970 to 3,120 ft). The Late Aptian climate was arid with high evaporation rates which triggered hypersaline conditions in these marginal sag basins. This resulted in the accumulation of thick layers of evaporites along the Brazilian and southwestern African continental margins, a process continuing towards the north later in the Cretaceous. The deposition of the lowermost 600 metres (2,000 ft) of salt in the Aptian would have taken approximately 20,000 to 30,000 years. With the continental break-up of the Santos and Campos Basins from the opposite Namibia and Kwanza Basins, oceanic circulation returned during the post-rift stage. The drift phase since the Late Cretaceous produced a thick sequence of clastic and carbonate deposits. Differential thermal regimes and sediment loading of these units produced halokinesis; salt movement in the subsurface. The resulting salt diapirs, listric and thrust faults and various salt-related structures produced several stratigraphic and combined stratigraphic-structural traps for hydrocarbon accumulation in the Brazilian and southwest African offshore.
During the phases of halokinesis, dated to the Albian to Paleocene, several areas of the now deep water distal part of the Santos Basin were exposed to subaerial conditions and suffered erosion. The distal parts of the basin were affected by E-W to NW-SE oriented shortening, sub-perpendicular to the Brazilian margin.
Santos Basin