Integration of Multidisciplinary Tools for Study of the Tectonic-Stratigraphics Features in the Post-Rift Sequence in Camamu-Almada Basin, Bahia State, Brazil

Márcia K. Karam¹, Nilo Chagas de Azambuja Filho², and Luiz Landau^3
1 Federal University of Rio de Janeiro State, Rio de Janeiro, Brazil
² PETROBRAS, Rio de Janeiro, Brazil
³ Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil

The study covers an area of 6.000 km2 in the offshore region of the Camamu-Almada basin, Brazil, and a data set of fourteen 2D seismic sections and 8 wells. The study was performed in the interval lithostratigraphic interval known as the Urucutuca, Rio Doce and Caravelas formations, representing a time lapse of circa 55 Ma.

An erosional feature, named the paleocanyon of Itacaré, latu sensu, was interpreted mainly based on 2D seismic sections. Such feature is the result of the erosion that has generated the well know in the region as the Pre-Urucutuca Unconformity, which can be related to a third-order tectono-eustatic events, which took place in the studied basin during the Coniacian. Late reactivations of faults, in heritage from the rift phase, rendered the formation of a channel, which caused intense incision, resulting in the observed paleocanyon morphology.

Seismic stratigraphy studies were conducted in order to deciphering the filling of the paleocanyon. It was made possible to interpret three seismic-stratigraphy sequences (D1, D2 and D3), which were related to a deep-water depositional system (D1) and to a platform to slope system (sequences D2 and D3). This indicates a progressive relative lowering of the sea level conditions from the Eocene to the top Oligocene as consequence of the filling of this feature.