Study of Pratinha-Ii Magnetic Anomaly: Acquisition, Processing and Interpretation of Aeromagnetic and Gravimetric Data

Aeromagnetic and aerogammaspectrometric data indicate the presence of a deep geological structure of unknown dimensions and composition near Pratinha-MG in SE Brazil. The anomaly is located in an economically interesting area with known occurrences of ore deposits currently explored by mining companies. The magnetic data suggest that the anomaly is caused by two nearby sources, but the proximity of them and surrounding anomalies, the interference of faults in the area and the anomaly’s low amplitude are challenges for the analysis. Different magnetic boundaries and depth estimating methods were applied and we were able to obtain reasonable values for the sources’ parameters. Those parameters were used to constrain 3D inversions of the magnetic data. The gravimetric data is still insufficient for a quantitative analysis and for comparison with the results obtained from the magnetic data. This study is part of a more comprehensive project by the Laboratório de Geofísica da Litosfera do IAG-USP that includes several alkaline complexes in the S-SE portion of Brazil.