Análise estratigráfica da seção rifte onshore da Bacia Potiguar (RN) na porção Sudoeste do Gráben de Umbuzeiro, adjacente à falha de Baixa Grande

Abstract

The Potiguar Basin is located in the limit between the Equatorial and East Brazilian Margins, geographically corresponding to Rio Grande do Norte and Ceará states. This basin integrates the Cretaceous Rift System of the Brazilian Northeast and its tectonosedimentary evolution includes besides the Rift Stage, the Post-Rift and Drift stages. The data of wells (composite profile, well files and general archives of wells) and seismic data (3D volume and 2D seismic lines) were used for the stratigraphic analysis of the Rift Section, in its onshore segment of the Potiguar Basin (represented by the Pendência Formation), more precisely in the southwestern portion of the Umbuzeiro Graben, adjacent to the Baixa Grande Fault. Based on the compilation of sequence stratigraphy concepts, seismic stratigraphy and geophysical well logging methods (specifically the gamma-ray profiles), the stratigraphic interval of that section of the basin was characterized in detail. Wells analysis involved the characterization of the lithofacies and depositional systems. Further, seismic sections analysis resulted in the description and interpretation of reflector patterns, with the characterization of seismic facies, sequence stratigraphy units and their boundary surfaces. As a result, four tectonic systems tracts ¬(TST) were recognized, which were named as: Rift-Initiation TST, Half-Graben Development TST, High Tectonic Activity TS (which was subdivided into tectonic pulses 1 and 2) and Rift Quiescence TST. This work aims at the integration of 1D and 2D analysis and the proposition of a tectonostratigraphic evolution model for the onshore Rift Section of a Meso-Cenozoic Transform Margin Basin.