Dobramentos distensionais e a geometria da falha de Baixa Grande, Graben de Umbuzeiro, Bacia Potiguar (RN)

In spite of significant study and exploration of Potiguar Basin, easternmost Brazilian equatorial margin, by the oil industry, its still provides an interesting discussion about its origin and the mechanisms of hydrocarbon trapping. The mapping and interpretation of 3D seismic reflection data of Baixa Grande Fault, SW portion of Umbuzeiro Graben, points as responsible for basin architecture configuration an extensional deformational process. The fault geometry is the most important deformation boundary condition of the rift stata. The development of flat-ramp geometries is responsible for the formation of important extensional anticline folds, many of then hydrocarbon traps in this basin segment. The dominant extensional deformation in the studied area, marked by the development of normal faults developments, associated with structures indicative of obliquity suggests variations on the former regime of Potiguar Basin through a multiphase process. The changes in structural trend permits the generation of local transpression and transtension zones, which results in a complex deformation pattern displayed by the Potiguar basin sin-rift strata. Sismostratigraphic and log analysis show that the Baixa Grande Fault acts as listric growing fault at the sedimentation onset. The generation of a relay ramp between Baixa Grande Fault and Carnaubais Fault was probably responsible for the balance between subsidence and sedimentary influx taxes, inhibiting its growing behaviour. The sismosequences analysis s indicates that the extensional folds generation its diachronic, and then the folds can be both syn- and post-depositional