Geophysical evidences of doming in the deep structuring of the Seridó Belt (NE-Brazil)
Potential field data; Geophysical modeling; Doming; Seridó Belt
The Seridó Belt and its basement compose a geologic region of great complexity located in the northeast part of the Borborema Province/Brazil. It is formed by a belt of metasedimentary rocks with NNE-SSW direction, which was deformed and metamorphosed at the end of the Neoproterozoic, around the apex of Pan-African-Brazilian Orogeny. Three major domains compose its basement: the São José do Campestre, Rio Piranhas-Seridó, and Transversal Zone domains. The surface geology of the region is well known, but the understanding of its deep structures is still limited. Investigating the crustal framework of the region is of scientific and economic interest because this might allow reconstructing the geologic events and understing aspects related to the spatial distribution of mineral occurrences, such as the presence of structures associated with fluid migration. The availability of recent gravity and aeromagnetic data, integrated with information from new geological studies, allows a more detailed interpretation. The objective of this work is to contribute to fill the existing gap and update the geological knowledge. For this, we perform a qualitative interpretation of aeromagnetic and gravimetric data to characterize the main geological aspects of the area. Quantitative approaches are also used to evidence the deep tectonic structures: we perform a 2.5D forward modelling of potential field data profiles, guided by measurements of magnetic susceptibility and density obtained in the Riacho Fechado stratigraphic hole (FDS001 / CPRM), Currais Novos – RN, besides an inversion of the magnetic data using the magnetization vector inversion tool (VOXI-MVI). The results are consistent with the existence of a dome structure, associated with a long-wavelength magnetic anomaly and located in the center-south portion of the Seridó Belt, with a preferred direction NE-SW and verge to the south for EW, following the Patos Lineament.