Prospectivity analysis of gold and iron oxide copper-gold-(silver) mineralizations from the Faina Greenstone Belt, Brazil, using multiple data sets

Abstract

ABSTRACT:The Faina Greenstone Belt is located in the southern sector of the Goiás Archean Block and has been investigated since the 18 th century because of its gold deposits. Recent studies have revealed the polymetallic potential of the belt, which is indicated by anomalous levels of Ag, Cu, Fe and Co in addition to Mn, Ba, Li, Ni, Cr and Zn. This study was developed based on a detailed analysis of two selected target sites, Cascavel and Tinteiro, and multiple data sets, such as airborne geophysics, geochemistry and geological information. These datasets were used to create a final prospectivity map using the fuzzy logic technique. The gold mineralization of Cascavel target is inserted in an orogenic system and occurs in two overlapping quartz veins systems, called Mestre-Cascavel and Cuca, embedded in quartzite with an average thickness 50 cm and guidance N45º-60ºW/25ºSW with free coarse gold in grains 2-3 mm to 3 cm. The prospectivity map created for this prospect generated four first-order favorable areas for mineralization and new medium-favorability foci. The Tinteiro area, derived from studies conducted by Orinoco do Brasil Mineração Ltda., shows polymetallic mineralization associated with an iron oxide-copper-gold ore deposit (IOCG) system posterior to Cascavel target mineralization. Its prospectivity map generated 19 new target sites with the potential for Au, Cu and Ag mineralization, suggesting new directions for future prospecting programs. KEYWORDS:Faina Greenstone Belt; aeromagnetometry; gamma spectrometry; gold mineralization; polymetallic mineralization; fuzzy logic. RESUMO: O Greenstone Belt INTRODUCTIONGlobally, mining companies seek to utilize prospective efficient methods that decrease costs during mineral exploration stages. To achieve such goals, they must use techniques that efficiently aggregate the data generated in the different stages of a given study by focusing on models that have a greater likelihood of estimating deposits (Robert et al. 2007). Magnetic surveys coupled with high-resolution gamma spectrometry data represent available technology in airborne geophysics for the detection of relevant structures for mineral exploration, and they have been shown to be efficient in the selection of follow-up target sites in tropical terranes (Silva et al. 2012, Carrino et al. 2011.The Faina Greenstone Belt is the target of this study, and, along with the Pilar de Goiás, Guarinos, Crixás and Serra de Santa Rita belts, it is part of the granite-greenstone terranes of the Archean-Paleoproterozoic terrane of Goiás, which is located in the northern sector of the Brasília Belt (Pimentel et al. 2004, Jost et al. 2005, Jost et al. 2013. This region has been investigated since the time of the Bandeirantes explorers (18 th and 19 th centuries) and shows the potential to host gold (Au) mineralizations. Several companies have mined in the area, including the well-known Metais de Goiás S.A. (METAGO), Western Mining Co., Amazônia Mineração and Troy Resources Brazil.The discovery of Sertão, a low-tonnag...

Integração De Dados Aerogamaespectrométricos E Eletromagnéticos Terrestres Em Região De Ocorrências De Cobre No Extremo Noroeste Da Bacia Do Camaquã, Sul Do Brasil

“…Os dados negativos (Tabela 3) foram removidos de acordo com a adição de constantes a cada canal, de modo a resultar em valores mínimos correspondentes a 0.01 (Ferreira et al, 2009;Weihermann et al, 2016). O processamento dos dados aerogamaespectrométricos foi encerrado a partir da elaboração de malhas regulares de 125 m x 125 m (correspondentes a ¼ do espaçamento das linhas de voo) pelo método de mínima curvatura (Briggs, 1974) dos valores corrigidos (Tabela 3) dos canais K (%), eTh (ppm) e eU (ppm), bem como na elaboração da respectiva composição ternária RGB, das razões eTh/K e eU/K, do Parâmetro F e do Potássio Anômalo (𝐾𝐾 𝑑𝑑 ), usando a versão 9.6 do programa Oasis Montaj, da Seequent Inc. O Parâmetro F ressalta o enriquecimento de potássio e urânio em relação ao tório, podendo sugerir áreas com alteração hidrotermal potássica associadas a mineralizações (Gnojek & Perichystal, 1985;Biondi et al, 2001;Fornazzari Neto & Ferreira, 2003;Ferreira et al, 2009;Barbuena et al, 2013;Campos et al, 2017). O Parâmetro F é indicado pela seguinte equação:…”

Geophysical-Structural Framework in a Mineralized Region of Northwesternmost Camaquã Basin, Southern Brazil

“…Geophysics has been applied in numerous studies to establish geological and tectonic compartmentalization in the last decades, as well as distinguishing lithotypes and identifying structures and lineaments, especially in inaccessible areas (Hallinan et al, 1993;Fernandes et al, 1995;Nogueira et al, 2004;Carvalho et al, 2006;Barbuena et al, 2013;Ramos et al, 2014;Castro and Ferreira, 2015;Gastal et al, 2015;Kosaroglu et al, 2016;Campos et al, 2017;Araffa et al, 2018;Weihermann et al, 2018;Osinowo and Abdulmumin, 2019;Alatorre-Zamora et al, 2020).…”