Estratigrafia de sequências dos depósitos marinhos profundos do Albiano ao Eoceno no setor offshore oeste da Bacia Potiguar, Margem Equatorial Brasileira

Abstract

The Potiguar Basin was created as a result of the distensional events responsible for the fragmentation of Pangea and the consequent creation of the African and South American continents. It is part of the set of basins originated due to the deployment of the Brazilian Equatorial Margin. In the Potiguar basin, detailed studies focused on deep water sequence stratigraphy still remain infrequent. Thus, this research aims to better understand the tectonostratigraphic evolution of the studied area, more precisely within the interval between the early Albian and middle Eocene unconformities (sensu Pessoa Neto et al., 2007), which includes the sequences of the transgressive drift phase and its change to the regressive drift phase of the basin. With well data, seismic lines and a 3D seismic volume, the section of this study was investigated in order to identify the depositional sequences, their internal units, chronostratigraphic boundries, seismic facies, lithofacies and associated depositional systems. The results of this investigation are eight stratigraphic sequences, named S1, S2, S3, S4, S5, S6, S7 and S8, considering the higher resolution analysis from the well data; these sequences, in the seismic data, were grouped in three seismic stratigraphic units, US1, US2 and US3, with the oldest two of them being transgressive. This study, based on models applied to the deep marine depositional environment, aimed to understand the nature of sedimentation on the shelf edge and its influence on more distal sectors of the basin, since such processes considerably control the gravitational fluxes responsible for the transport, dispersion and deposition of sediments in deep waters. Besides this, it is important to note that the Potiguar Basin has an exploratory history for hydrocarbons, focused on its onshore portion. However, the recent oil discoveries in its correlated basin in West Africa, the Benin Basin, signals a real possibility of discoveries of new exploratory plays in the offshore portions of this basin, mainly associated with turbidite deposits.