Geological structures in western edge of Santos basin and adjacent Ribeira belt from broad band magnetotellurics and geological mapping

During the Neoproterozoic the movement, the collision and the collage of tectonic plates formed a supercontinent called Gondwana. The Ribeira Belt has oriinated from the formation of the supercontinent Gondwana, and extends approximately 1400 km along the Brazilian coast. It surrounds the Sao Francisco Craton in its southeastern edge, transitioning to the west to the Brasilia Belt. The Ribeira Belt comprises several tectonic lands not yet fully correlated. One can observe Proterozoic volcanicsediments from different source sequences and Neoproterozoic-Eopaleozoic pluton´s compositions of both different ages and deformation/metamorphism degrees that have been intruded on the basement. We carried out 81 MT broad band soundings with remote reference, with acquisition frequencies of 4096 Hz, 512 Hz and 128 Hz. These soundings are distributed into two parallel profiles, approximately 50 km apart and 5 km spacing between soundings. . Good quality data were collected in the period range of 0.001–100 s. Data were processed using a robust remote-reference technique. Strike and dimensionality analysis along with G-B decomposition support a general 2-D regional character of the conductivity distribution in the area, allowing us to create a 2-D inversion model. Good misfit can be observed between the measured and calculated transfer functions projected onto the profile direction. These profiles crossed Brasilia and Ribeira Belts, as well as several geosutures in the basement of the marginal basins of southeastern Brazil. The geophysical survey associated with the available geological information brought important contributions to the understanding of the main geosutures presents in the area. Results imaged the two main suture zones between the orogenics belts and allow inferences about the geographic position of their lateral limits.