Abstract:
During the Neoproterozoic, a combination of movement, collision and collage of tectonic plates formed the supercontinent Gondwana. After its break in the Cretaceous, leading to continental breakup between Africa and South America, ancient mobile beltssuch as the Brasilia and Ribeira belts remained on the Brazilian side right on the southeastern portion. These crustal blocks are separated by old geosutures contemporary with the assemblage of Gondwana. The study area is situated between the continental margin and adjacent land area of Brazil. 2D modeling technique was used for calculating the responses of available gravity information with constraints posed by current geological model and other geophysical models. In the crust, the adjustments to the observed data were obtained with different simulations, varying the density of a hypothetical distribution of available geological and geophysical information. In the crust, observed fitting of different simulations were achieved by varying the density of a hypothetical distribution of available geological and geophysical information. In the lithospheric mantle, the model fitted the data with the inference of keels and wedges at the base of the lithosphere, possibly subducted chemically homogeneous paleoplates. In the area of the continental margin, crustal and lithospheric thinning was found beneath both the coastal plain / shallow shelf and in the proximal portion of the Santos Basin. The geologic model resulting from the merger of the geological and geophysical information corroborates the existence and delimits the two suture zones between tectonic terrains of the Brasilia and Ribeira Belts and the terrains separating the Ribeira Belt from Santos Basin, proposed in previous studies. This model fits the observed gravity data with less than 8% of the total gradient error.
