Application of airborne geophysical data to mineral exploration in the uneven exposed terrains of the Rio das Velhas greenstone belt

Abstract

The highly prospective nature of the Rio das Velhas Greenstone Belt is known since the end of the last century. Archean greenstone-hosted gold deposits represent a distinctive group with many common characteristics. The geophysics approach employed concentrated on processing and enhancing the geophysical data to accurate positioning of geological boundaries. The rationale was that in exploration, we should not be looking for geophysical anomalies, but the responses related to mineralization, lithology, and structure that may have economic importance. Aeromagnetics identifies magnetic greenstone units, important structures related to mineralization and allowed a better understanding of sctrutural geophysical pattern. The radiometric data was an excellent tool for mapping and trace individual lithological units in the in areas of outcrop. The most important host rocks or mineralized domains show high conductivity response. There is a strong correlation of these domains with the mapped Morro Vermelho, Quebra Osso and Ouro Fino Formations. Such domains host the known gold mineralization, illustrating the utility of the EM data to improve the geologic map.