A new gravity survey was conducted between coordinates 39º to 49ºW and 17º to 23ºS in SE São Francisco Craton. A total of 176 new gravity stations was obtained. The position of each gravity station was determined using GPS (Global Positioning System) relative positioning method. The new data was added to the gravity data-bank of IAG (Instituto de Astronomia, Geofísica e Ciências Atmosféricas)/USP (Universidade de São Paulo). A total of 12,339 stations was processed and interpreted. The geology of this area is represented by Archean and Proterozoic metamorphic terrains of SE São Francisco Craton, including the Araçuaí and Ribeira fold/thrust belts. In order to separate shallow from deep sources of gravity field, a 50 km upward continued regional field was removed from Bouguer anomaly map. The residual gravity field from the Quadrilátero Ferrífero was correlated with the exposed geological units. The main gravity anomalies were forward modeled in order to map the contact between the main metamorphic complexes. Metamorphic complexes in this area have distinct gravity signatures. Bação and Caeté metamorphic complexes have negative gravity anomalies with similar amplitude. Bonfim metamorphic complex has positive gravity anomalies and its limits extend beyond the geologically mapped area, under younger sedimentary sequences. Forward gravity modeling constrained by observed geological contacts allowed to estimate the directions and dips of two major tectonic contacts. The contact between Barbacena and Bonfim metamorphic complexes dips 21º northward, whereas Belo Horizonte complex dips 31º westward under the Rio das Velhas supergroup.
gravity; gravity anomalies; iron formation; São Francisco Craton
