Stratigraphic and structural analysis of the Rio do Peixe Basin, Northeastern Brazil: integration based on the pioneer seismic survey 0295_RIO_DO_PEIXE_2D

Abstract

The Northeast Brazil Interior Basins are the erosional remnants of a series of basins located south of the Potiguar Basin, overlying the crystalline basement of Precambrian Borborema Province. These basins were originated during the Early Cretaceous rifting that shaped the present continental margin of northeastern Brazil. Besides their exploration potential, the Interior Basins represent terrain analogues for better understanding of the continen-tal margin basins, one of the objectives of the Interior Basins Project (agreement Petrobras / UFRN /PPGG), which supported the seismic survey in the Rio do Peixe Basin, subject of this paper. Combined with gravity and field data, the seismic sections allowed an improved view of the three-dimensional architecture of the Rio do Peixe Basin. In this basin, the combination of the current erosion level with the geometry of the main faults highlights the existence of different half-grabens (Pombal, Sousa, Brejo das Freiras), whose sedimentary filling (apart from cenozoic deposits) defines the Rio do Peixe Group, comprising the Antenor Navarro (alluvial fans /braided channels), Sousa (shallow lacustrine /floodplain) and Rio Piranhas (alluvial fans / braided channels). Structural data integration allows characterization of a NW-extension kinematics for the rifting event, responsible for fault nucleation controlled by basement structures, particularly the location and foliation dip of the Late Neoproterozoic, Brasiliano shear zones. Based on the structural style and petrographic-diagenetic features, one can infer larger original dimensions for this basin and similar counterparts in the region, which were reduced (with exposure of the crystalline highs) by the significant erosion that occurred in late to post-rift and subsequent evolutionary stages.