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...
Duricrusts ferruginosos e aluminosos e relações pedologia-geomorfologia-geologia no Alto Jequitinhonha (MG) / Daniela Schievano de Campos --versão revisada de acordo com a Resolução CoPGr 6018 de 2011. --Piracicaba, 2023. 229 p. Tese (Doutorado) --USP / Escola Superior de Agricultura "Luiz de Queiroz". 1. Plintossolo Pétrico 2. Couraça ferruginosa e bauxítica 3. Índices geomórficos 4. Litologia resistente 5. Evolução da paisagem I. Título DEDICATÓRIA A minha querida mãe, companheira e melhor amiga. Você é responsável por todas as minhas conquistas. 4 AGRADECIMENTOS A Deus. Aos meus pais, Márcia e João, pelo apoio incondicional, pela confiança e pelo carinho recebidos durante esses longos anos. Ao meu querido orientador Pablo Vidal-Torrado, pela imensa dedicação, paciência e amizade. Eu posso afirmar com certeza que estes foram os meus anos de maior aprendizagem. E quando o senhor diz "queria ter um orientador assim!", eu tenho orgulho e o privilégio em responder "pois eu tenho!". Aos meus co-orientadores Prof. Marcilene dos Santos, Dra. Hevelyn Monteiro, Prof. Paulo Vasconcelos, Prof. Alexandre Christófaro e Prof. Danilo Camêlo, por todo apoio e aprendizagem recebidos. Vocês foram fundamentais para o meu crescimento profissional e pessoal.Ao CNPq pela concessão da bolsa de doutorado (Processo n° 140833/2018-8) que viabilizou todos esses incríveis anos de pesquisa.
<p>Post-rifting and dead orogens landscapes have presented topographic rejuvenation long after intense tectonic activity ceased, resulting in relief growth in a topography that was expected decay.In addition, there is compelling evidence of low denudation rates in tropical post-orogenic landscapes, mainly related to low-relief uplands capped with duricrusts.Thus, understanding the evolution of these landscape settings has proven enigmatic. Recent studies have invoked the contrasting rock strength as primary factor for such topographic rejuvenation. In contribution to this issue, we investigated the topographic signals in a post-orogenic and post-rifting Brazilian landscape with low contrasting rock strength, the Southern Espinha&#231;o Range(SER). In order to reveal potential relief growth, we explored interactions between drainage signatures, topographic metrics, bedrock inheritance and duricrusts. We extracted local relief, hillslope angle, and normalised channel steepness, and performed knickpoint and stream profile analysis to explore spatial variations in topography of the study area. Our findings suggest that the post-rifting evolution of the study area is dictated by episodic uplift and base level fall events coupled with favored stress concentrator zones, which accelerate channel incision and trigger ongoing dismantling of duricrusts. Knickpoints at high elevation separate a relict low-relief landscape upstream, capped by either Fe or Al duricrusts, from a transient adjustment zone downstream, indicating that records of different boundary conditions coexist in the landscape. This study shows a contradiction between low denudation rates and topographic rejuvenation even in a low contrasting rock strength domain. We have found that interactions between surface processes and pre-existing weakness zones likely occur in the SER, highlighting how enigmatic and complex long-term landscape evolution can be in ancient post-orogenic and post-rifting settings.</p>
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 the 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 multisource data, such as airborne geophysics, geochemistry and geological information, were used to create a final prospectivity map from the integration of all these data. The applied methodology used to obtain this map was fuzzy logic. 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 of 50 cm and guidance N45°-60°W/25°SW with free coarse gold in grains 2-3 mm to 3 cm. The potentiality 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 Ltd., shows polymetallic mineralization associated with an iron oxide copper gold ore deposit (IOCG) system poterior 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.
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