Aeromagnetometric data aplication to investigate the magnetic basement - Caçapava do Sul, RS

Abstract

The evolution and understanding of the granitic intrusive rock structures in the southern Rio Grande Shield (SRGS) are fundamental to supporting the investigation of mineral occurrences in the state of Rio Grande do Sul, Brazil. This mineral province is classified as complex with igneous, metamorphic, and sedimentary rocks of the Archean to Neopaleoproterozoic age. The main objective of the present study was to investigate the Caçapava do Sul Shear Zone (CSSZ), of which, despite its role as a terrain boundary, its kinematic importance at a regional scale is still questioned. With this objective, aeromagnetometry data were used to enhance the lineaments, trace the domains and estimate the depth of the basement surface related to the formation of the Caçapava do Sul Granitic Complex (CSGS) and consequently the CSSZ. In addition, 3D Euler deconvolution and Source Parameter Imaging (SPI) techniques were applied to estimate the depth of the magnetic basement surface. The 3D Euler deconvolution provided the estimated depth of structural features internal and external to the CSGS. Among the identified features, they include the transcurrent shear zones located at the internal boundaries of the CSGS associated with the tectonic evolution of the granitic body. The joint interpretation of the SPI technique with the 3D Euler deconvolution evidenced the influence of the CSSZ on the magnetic basement, showing even less influence of this feature on its southwestern limits (decrease in the depth of the magnetic basement). This work, through the application of enhancement techniques, evidenced the influence of the Shear Zones on the surface of the magnetic basement. In this way, the results found in this work provide subsidies with greater weights for future geological mappings and studies focused on the evolution of the CSGS.