Evolução tectono-estratigráfica da seção cretácea na Bacia de Barreirinhas, Margem Equatorial Brasileira

Abstract

The basins of the Brazilian Equatorial Margin (BEM) have received increasing attention due to hydrocarbon discoveries in their African conjugate counterparts. The Barreirinhas Basin, although presenting high exploratory potential, still shows significant gaps in the understanding of its tectonostratigraphic evolution. This study analyzes the structural and stratigraphic framework of the onshore portion and shallow platform during the Cretaceous, through the integration of 2D seismic data, well geophysical logs, and previously published gravity data. The tectonostratigraphic characterization was based on the mapping of major unconformities and the application of sequence stratigraphy concepts, allowing the evaluation of the relationship between tectonic activity and depositional systems. The rift section was subdivided into five seismic-stratigraphic units, defined by the analysis of seismic facies, reflector terminations, and intra-rift unconformities. Lithostratigraphic and chronostratigraphic data from wells provided additional support for the calibration and validation of the interpretations. The seismicstructural analysis enabled the identification of grabens, half-grabens, and horsts, bounded by high-angle normal faults predominantly associated with the rifting stage and controlled by heterogeneities of the crystalline basement, with orientations ranging from E–W to NW–SE. In the context of the evolution of the Barreirinhas Basin pull-apart system, depocenters related to Rift Phases I (late Barremian to late Aptian), II (late Aptian to early Albian), and III (early Albian to late Albian) were analyzed. The construction of regional sections (transects) allowed the visualization and understanding of stratigraphic relationships critical to the regional context of the Barreirinhas Basin, which was directly influenced by the Romanche Fracture Zone (RFZ), imprinting transtensional structures as the dominant regime and transpressional features subordinately.