Abstract Gold mining has profound ties to the history of Brazilian colonization and still takes place with many communities involved in artisanal and small-scale gold mining. The most relevant gold deposits in the Southern Espinhaço Range are related to the occurrence of shear zones in the region between the cities of Diamantina and Gouveia, Minas Gerais, Brazil. Former colonial-dated gold mines were depleted; however, the use of newer prospecting practices has brought new interest in these areas. In this context, this study assesses the efficiency, environmental impacts, and economic viability of time-domain electromagnetic induction as a gold exploration method for small-scale prospecting in Gouveia county. Additionally, this study provides a characterization of the local gold mineralization and brings awareness to the prospecting community regarding environmental and legal aspects of gold mining. This article presents the results of a field campaign of prospecting efforts in which 114 metallic targets were located, 35 of which were identified as native gold. The gold samples have specific morphology, depth, and weight that suggest a hypogenic origin with a low degree of transport at eluvial levels. From an environmental perspective, the time-domain electromagnetic induction method has presented fewer impacts, related mostly to site-specific remobilization of the soil.

ABSTRACT: The Espinhaço rift system encompasses taphrogenetic events from the Statherian to Tonian in the São Francisco-Congo (SFC) paleocontinent. The magmatism is represented mainly by metamorphosed anorogenic granites and rhyolites with subordinate amphibolites. Zircon U-Pb (LA-ICPMS and SHRIMP) ages from felsic (1748 ± 3 Ma and 1740 ± 8 Ma) and mafic (1725 ± 4 Ma) rock samples, coupled with previous studies suggest that the Espinhaço igneous province erupted from ca. 1.79 Ga to ca. 1.70 Ga. The felsic rocks show characteristics of A-type magmas. The negative εHf(t) data for meta-rhyolite zircons (-12.32 to -17.58), the moderate δ 18 O values (7.02 to 7.98) and the REE patterns suggest crustal melting related to an extensional environment. The mafic rock shows negative values of εHf(t) in zircons (-4.05 to -8.25) and moderate δ 18 O values (5.56 to 7.87). The results disclose a basaltic magmatism in continental intraplate setting whose parental magma could have been derived from the subcontinental lithospheric mantle with contamination of crustal material. These data coupled with coeval Espinhaço magmatism and mafic dyke swarms found to the south of the Espinhaço rift system reinforce the evidence of a long-lived Statherian silicic large igneous province (SLIP) on the SFC paleocontinental block.