Geophysical Characterization of a Potentially Mineralized Target in Copper Sulfides in the Northwest Limit of Camaquã Basin, Brazil

Abstract

This work describes the reconnaissance and detailed phases of a potential copper sulfide mineralized target situated between the Sul-Riograndense Shield and the Camaquã Basin. The study area comprises the Victor Teixeira and the Capão Grande copper occurrences. These were recognized and catalogued in the 1960s by the Brazilian Department of Mining Production (DNPM in Portuguese) in the countryside of Caçapava do Sul, Rio Grande do Sul State, Brazil. These occurrences are delimited in the surface by malachite and azurite disseminated mineralizations which fill fractures and sandstone and schist pores. The initial phase of reconnaissance involved a gravimetric survey that revealed an anomaly with high amplitude between the copper occurrences. The forward modeling of this anomalous peak showed a body with significant density, which was related to chalcocite, and motivated the use of resistivity and induced polarization in the detailed phase. Our data were associated with a conductive body and three resistive and three polarized bodies. The correlation between the conductive and the polarized bodies (situated below 60 m) was associated with sulfides in the subsurface. The resistive bodies situated above the polarized ones were attributed to silicified portions in the country rocks. The combination of procedures based on the geophysical analysis in an area delimited by structural and metallogenetic control showed efficiency in the prospect of the buried target, which is a common paradigm in current minerals research.