Geometria e Evolução Tectônica da Porção Norte do Gráben de Merluza, Bacia de Santos

• Autor(a) principal: Carvalho, Eduardo Batista Antunes de
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/7125
• topic: Merluza Graben; Santos Basin; Merluza Transference Zone; Capricorn Lineament; Gráben de Merluza; Bacia de Santos; Zona de Transferência de Merluza; Lineamento Capricórnio; CNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIA::GEOTECTONICA

The Merluza Graben is a deep and elongated extensional structure within the Santos Basin, stretching for ~ 170 km in NNE direction, offshore the São Paulo State in SE Brazil. The present work aims to characterize the geometry of its northern segment as well as to relate subsidence events, sedimentary fill and periods of boundary fault reactivation. Also, to establish a correlation with other events in the Santos Basin and and adjoining continental portion. Eleven bi-dimensional (2D) seismic sections, provided by the Brazilian National Petroleum Agency (ANP), were reprocessed, migrated in time and interpreted. Three of the sections (248-0041, 248-0045, and 248-0048) were detailed and used to define the graben s main geometry and tectonic features. Eleven tectonic sequences were identified in the three main seismic sections: one pre-salt, followed by the evaporitic strata, and nine post-salt sequences. Due to the low quality of the seismic data in the deepest portions, it is not possible to safely precise the age of the graben s initial opening. However, it has been verified that the main fault may reach greater depths than the ones observed on the seismic lines, that is, over 1500 milliseconds. Based on the presence of a pre-salt sedimentary section within the graben, itself affected by tectonics of the basement, we can estimate a minimum Aptian age. The northern portion of Merluza Graben is characterized by a main west-dipping border fault and by an east-dipping subordinated fault. The limit between the Northern and Central Portions is given by the Merluza Transference Zone, also known as Capricorn Lineament. Such feature has regional expression within the basin and is responsible for a change in direction of the main fault of the Merluza Graben, which then dips to the east, while the secondary fault dips to the west. As for the horst which follows the main fault in the northern portion of the graben, thick salt domes developed, originated by the scape of the evaporitic sequence towards east. The major movement of the main fault took place between the Cenomanian and the Santonian, with a strong offset, as well as an expressive volume of sediments coming from the continent, reaching over 4,000 m, owing to the erosion of the Cretaceous Serra do Mar coastal ranges. During the Cenozoic, reactivations of the graben s border faults are observed, along with compaction of the higher layers and to salt tectonics. Such events may be related to Paleocene-Eocene tectonic reactivations related to the evolution of the Southeast Brazil Continental Rift System. Observed progradational features suggest that the Merluza Graben conditioned the location of the platform-continental slope transition in this very region during the Neogene.