Interpretação Magnetométrica da Bacia de Santos e Região Emersa Adjacente: caracterização dos enxames de diques e seu prolongamento na margem

Abstract

The southeastern margin of Brazil is a region marked by the Gondwana rifting process related to the Early Cretaceous and it is understood as a complex tectonomagmatic province associated with the basic and alkaline magmatism described by the Paraná-Etendka Magmatic Province (PEMP) also expressed as dyke swarms of Florianópolis (FDS), Ponta Grossa (PGDS) and Serra do Mar (EDSM). Most of the dyke swarms of the PEMP have already been mapped and described in the onshore portion of South America and Africa, but information is still lacking on the full extent of these dyke swarms in the offshore portion, which is a crucial point in terms of geodynamic reconstruction of the Gondwana. This work aims to integrate high resolution onshore and offshore airborne magnetometric data to generate thematic geophysical maps - such as the pole reduced magnetometric map (RTP) - to collaborate with the mapping of the dyke swarms in the Santos Basin. Magnetometric domains were also identified through geophysical maps being associated with geotectonic units of the studied area. It was identified the signal associated with the FDS, PGDS and EDSM dykes, as well as the extension of this same signal in the proximal region of the Santos Basin. Seismic reflection data acquired on the offshore magnetic lineaments point to a disturbance of the reflectors in the region of the extension of the DS signal, suggesting the possible extension of the FDS, PGDS and EDSM swarms in the proximal domain of the basin. Magnetometric domains were also identified through geophysical maps being associated with geotectonic units of the studied area. The magnetometric data also point to a series of anomalies and magnetometric patterns that were discussed associated with the domains of the margin and features of the Santos basin. The region associated with the Necking Zone presents a pattern little affected by magmatism and the Distal Domain in the São Paulo Plateau exhibits a magnetic pattern of high amplitude and distinct directions when compared to the other marginal domains, suggesting a change in the basement structures, with the presence of magmatism.