ICE 2022


The onset of magmatism combined with the distribution of lithospheric keels and scars inherited from Proterozoic cratonic collisions controlled deformation partitioning during the opening of the South Atlantic. Even though rifting was triggered by far-field stress, three plumes were active within the South American side: The Sierra Leone (SL) around the Demerara Plateau, the St. Helena (SH), partially inside the Borborema-Benin-Nigerian Province (BBNP), and the Tristan-Gough (TG) at the northern tip of the Austral Branch of the South Atlantic. Three LIPs are associated with each plume: The Sierra Leone in north South America, the Borborema LIP within the BBNP, and the Paraná Etendeka Magmatic Province-LIP between southern Brazil and Africa. Three Transform Marginal Plateaus (TMPs) are associated with the hotspot track of each plume: (a) The São Paulo TMP, associated with the TG plume in the Santos Basin; (b) The Pernambuco TMP, associated with the SH plume in Pernambuco Basin (NE Brazil); and (c) The conjugate Demerara and Guinea TMPs, associated with the SL plume. Two world-class deep-water oil provinces are associated with the São Paulo/Santos and Demerara-Guinea TMPs. (i) The oil-rich Santos Basin display large-scale basement-involved folding, with the presence of obliquely sheared active magmatic core complexes, which accommodated a large amount of extension through a large-scale accommodation zone between two competing rift/spreading centers that meet between the Santos and Pelotas basins. The margin was influenced by the thermal impact of the TG plume. Its transform boundary is the Florianópolis Fracture Zone. Proterozoic inheritance is the primary factor controlling deformation partitioning and the width of the Santos Basin. (ii) The Guyana/Suriname oil province is another example of a major oil reserves discovered around a TMP, but with quite distinct tectonic evolution and petroleum systems. The potential replication of the Guyana's success toward the Brazilian Equatorial Margin is discussed based on plate reconstruction, the nature of the crust and source rocks distribution. On the other hand, the so far oil deprived Pernambuco TMP, in NE Brazil, is an example of a TMP with no major oil reserves around it. It is associated with the hotspot track of the SH plume, when the continental crust was intruded and underplated. The Pernambuco TMP is bounded by the Kribi/Ascension fracture zones, at the junction of ocean basins of contrasting ages.