(APTIAN-ALBIAN INTERVAL)
|
|
|
|
|
|
|
|
The Sergipe Alagoas basin of the Brazilian margin was formed parallel with the Douala, Rio Muni, and Gabon sedimentary basins. These basins were formed in response to the Africa-South America rifting that began in the Jurassic time, allowing the formation of the South Atlantic Ocean. The sedimentary basins in the study area display many similarities and some differences in the section that ranges from Barremian through Maastrichtian stages. The main similarities include (1) the division of the lithology into three phases (syn-rift, transitional and post-rift), (2) the position of the transitional Aptian salt sequence between syn rift and post-rift phases, (3) the common west African rift-system that appears on both sides of the Atlantic Ocean, and (4) the change of the sea level of the Late Cretaceous time in these basins.CONCLUSIONS The differences shown by these basins for the same interval (Barremian-Maastrichtian) include (1) the persistence of the salt formation through Albian in the Gabon sedimentary basin, (2) the lithology of the salt sequence in the same basin, which consists of two different kinds of salt, (3) the lithology of the Aptian salt formation in the Rio Muni basin that contains some terrestrial sediments, and (4) the appearance of two different rift systems in the Sergipe Alagoas basin.
