Interpretation of radiometric ratios and magnetic anomalies from Morro Feio ultramafic complex, central-western Brazil

Abstract

This study was performed to identify magnetic structures in depth and radiometric responses within and around Morro Feio Ultramafic Complex (MFUC) from the airborne geophysical (gamma-ray spectrometry and magnetic) data. Using processing techniques and profiles analysis, we have found eight gamma-ray spectrometry signatures and twenty-seven magnetic anomalies. The radiometric signatures are basically characterized by a K and eU relative enrichment in detriment eTh, with two of these signatures also characterized by K relative enrichment in detriment eU. Based on published works, we have interpreted the radiometric responses may be from serpentinite and possible areas with hydrothermal alterations. Regarding the magnetic anomalies, we concluded that the shallowest may be the magnetic responses of dikes, contact zones and other structures, while the deepest have sources with more complex geometries and are concentrated in central-western of MFUC, where the participation of Pt is larger. In this aspect, our results reinforce the arguments favorable to existence of Pt, Cr and Ni primary sources in depth.