Investigação geológica e geofísica integrada na parte emersa da Bacia de Campos, entre Macaé e a Lagoa Feia.

Abstract

The thesis investigates the geometry of transfer faults system and a thrust fault in the onshore basement of the Campos Basin between Macaé and the Lagoa Feia in the state of Rio de Janeiro. The structures belong to the Southeast Rift System, which includes NE-SW trending grabens and NW-SE trending transfer faults reactivated in the lower Cretaceous and Cenozoic. This study made 162 gravimetric and DGPS stations, 47 magnetotelluric (MT) stations and aeromagnetic data from the Aerogeophysical São Paulo-Rio de Janeiro Project (CPRM) and 544 gravity stations of the National Observatory surveys. Filters were applied to potential methods data and magnetic and gravimetric maps were generated that were correlated with subsurface MT information and with surface geology. The 2D direct modeling (magnetometric and gravimetric) was carried out based on the obtained models of 2D magnetotelluric inversion. The Precambrian basement in the study area is represented by the Região dos Lagos Complex (Cabo Frio Terrane) and the São. Fidélis Group (Oriental Terrane). According to the 2D modeling, the physical properties of rocks (density, magnetic susceptibility and electrical resistivity) of the same lithological unit varies laterally and at depth up to 3 km, indicating that the rocks were affected by deep weathering and hydrothermal alteration. The 2D modeling through GM-SYS 3D and Voxi characterized the thrust fault as a suture between the Oriental and Cabo Frio terranes. The geophysical signature observed in the sections point to a conductive layer below the Região dos Lagos Complex. The transfer fault system is characterized by directional NW-SE faults associated with NE-SW and E-W faults with normal component. The NW-SE directional faults were called Macaé Fault (set of 3 faults), Carapebus, Quissamã and Lagoa Feia (set of 3 faults) and classified as transverse or transfer faults. These faults cross the entire upper crust to the lower crust and could be related to vertical conductors observed in MT sections. The extension of these failures in the offshore field in the Campos Basin corresponds to the edges of a horst and the presence of productive oil fields in the marginal basin.