Arcabouço tectono-estrutural da Margem Equatorial Brasileira: uma abordagem baseada em dados de sensoriamento remoto e geofísicos potenciais

Abstract

Along the Brazilian Equatorial Margin (BEM), a set of sedimentary basins have evolved from Neobarremian to Albian. This region has aroused significant interest due to recent discoveries of hydrocarbon reserves on the continental margins of Ghana, in Africa, and the Guianas/Suriname, in South America. However, the absence of exposures of the AptianAlbian rift and the overlap of brittle structures related to this event with older and/or younger structures related to the Neocomian-Barremian rift and post-Campanian intraplate deformation hinder the correlation of surface-mapped structures with transtractive/transpressive tectonic events related to the evolution of the Equatorial Atlantic. In this work, we carried out an analysis of the orientation and distribution of brittle lineaments in the onshore Brazilian and African equatorial margins. In more detail, and also considering field data, trends associated with surface brittle lineaments were compared with magnetic lineaments in the Potiguar, São Luís, Bragança-Viseu, Grajaú, and Barreirinhas basins. The results indicate continental influence of Albian tectonics reached the southern portion of the Grajaú Basin, suggesting dextral transtension of the BEM during the Albian and control of the inheritance of Brazilian shear zones from the Gurupi and Araguaia belts, Borborema Province, and the Transbrasiliano Lineament in the development and reactivation of brittle structures in various stages of the BEM evolution. Furthermore, a study of the deep crustal architecture in the offshore área of the BEM was conducted, integrating gravity, magnetic, and 2D seismic data. The BEM was divided into four domains: proximal (PD), neck zone (NZ), ocean-continent transition (OCT), and oceanic crust (OC). These domains exhibit a predominance of NW-SE normal and oblique-slip faults from Aptian to Albian, associated with E-W strike-slip and oblique-slip faults, as well as NE-SW folds and thrusts. Oceancontinent transitions can vary from gradual to abrupt, depending on the location and predominant structural style in each segment of the margin. The defined boundaries provided a good fit between the continental crusts of the BEM and the African Equatorial Margin (AEM) during the Cenomanian. This study contributes to a better understanding of basin formation mechanisms in the BEM, opening perspectives for exploring its petroleum potential in deep and ultra-deep waters.