CORRELAÇÃO DO MAGMATISMO DAS BACIAS DA MARGEM CONTINENTAL BRASILEIRA COM O DAS ÁREAS EMERSAS ADJACENTES

Abstract

CORRELATION OF MAGMATISM OF THE BRAZILIAN MARGINAL BASINS WITH THE ADJACENT EMERGED CONTINENTAL AREAS The available information on the Cretaceous-Tertiary magmatism in Brazilian marginal basins is synthesized, aiming at a comparison with similar events that affected the emerged adjacent areas. The Eocretaceous pre-Aptian basaltic volcanism is more common in the basins from Espírito Santo to the Sduth, where it can be correlated with dikes and lava flows of the Serra Geral Formation. It is also present in Northeast Brazil, at the southern part of the submerged Potiguar Basin. At the extreme south of Brazil, the presence of acid magmatism in the Paraná Basin allows one to suppose the existence of similar compositions in the poorly known Pelotas Basin. The quiescence of magmatism during Aptian-Albian time is a common characteristic of almost all Brazilian marginal basins, as well as in the emerged continental area, but rocks belonging to this age are present in the Ceará Basin and in the Cabo area (PE). Neocretaceous-Eocene magmatism of alkàline trend is present in the emerged region of the Cabo Frio Magmatic Lineament. Possibly it can be extended to the submerged margin. Eocene volcanism is very important at the Cabo Frio Platform and south of Campos Basin. The islands situated along the Santos BasirTs margin are composed by feldspathoid-bearing alkàline rocks, the emplacement of which is related to the Rio de Janeiro Lineament. The Tertiary volcanism in Northeast Brazil lasted until Miocene, in the Potiguar Basin and emerged region, but in South-Southeast Brazil it seems to have ceased after Eocene. The Fernando de Noronha Fracture Zone extended up to the coast, allowing the onset of Oligocene alkaline volcanism. The Remanche Fracture Zone extends up to the Ceará Basin and the São Luís Craton, and controls the acid magmatism observed in the Atlântico and Ceará highs. The Vitória-Trindade Fracture Zone also seems to extend to the continent, as suggested by the structures and basic dikes of the Fundão Suite. The basins situated between the Ceará State and the Marajó Island are amagmatic, as well as the Recôncavo Basin, in part because they have been installed on rigid crust of São Luís and São Francisco cratons. It is suggested that the faster continent withdrawal in the South as compared to the Northeast Brazil associated to different rift processes could have been the cause for cessation of volcanism only after the Miocene in the last region