APLICAÇÃO DA GEOFÍSICA AÉREA NA EXPLORAÇÃO MINERAL E MAPEAMENTO GEOLÓGICO DO SETOR SUDOESTE DO CINTURÃO CUPRÍFERO ORÓS-JAGUARIBE

Abstract

Mineral deposits like those of the Cu-Au-U-ETR-Fe-oxides class are commonly associated with hydrothermal alteration zones that are detectable by airbone geophysical methods. In The Pio IX, Sao Juliao and Fronteiras region (Piaui State), and Campos Sales region (Ceara State) there are copper occurrences in Eo-cambrian molassic basins, and others associated with fault breccias in hydrothermal alteration zones due to Post-Brasiliano granites (550 My) intruded in Mesoproterozoic ortogneisses and metavolcanic rocks of the Oros Group. This region is covered by the airbone geophysical survey called “Projeto Borda Leste da Bacia do Maranhao” (Magnetometry and Gammaspectrometry with flight line spacing of 1 km). The processing and interpretation of these data are presented here, with an aim to help geological mapping and mineral exploration. The magnetic images of anomalous field, first vertical derivative, analytical signal amplitude and phase, and 3D Euler deconvolution maps were used to delineate the structural framework and the magnetic domains. The RGB ternary image (K:Th:U) was used to delineate the gamma-spectrometric domains. The integration of the magnetic and gamma-spectrometric interpretation yielded a geological-geophysical map. The anomalous potassium and uranium images were used to identify probable zones of potassic hydrothermal alteration that suggest targets for future follow-up.