Relationship between airborne geophysical signatures and hydrothermal rocks with Cu-Au mineralization in the Mara Rosa Magmatic Arc, Central Brazil

Abstract

Due to the relevance and size of Mara Rosa Magmatic Arc, as well as the general lack of outcrop, airborne geophysics plays a major role in mineral exploration. Gold and gold-copper deposits of the Mara Rosa Magmatic Arc, Central Brazil, occur in four main associations: Au-Ag-Ba; Cu-Au; Au only and Au-Cu-Bi. New regional airborne geophysics have been undertaken to assist in geological mapping and select new favourable environments. The airborne geophysical results are compared with the distribution of known hydrothermal host rocks and outcrops where Au, Au-Ag-Ba and Cu mineralization occurs. Analysis of the data indicates high positive correlation between magnetic and gamma ray anomalies. Our study is focused on characterizing the geophysical properties of the hydrothermal rocks and associated mineralization that can host gold and copper. New spots, as two new geological targets for copper minerals, have been identified in the Mara Rosa Magmatic arc. The new copper-gold targets have clear physical property contrasts with their host rocks and therefore lend themselves to detection and mapping by airborne geophysical methods.