12 resultados para Minería Aurífera
em Repositório Institucional UNESP - Universidade Estadual Paulista "Julio de Mesquita Filho"
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Geociências e Meio Ambiente - IGCE
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Pós-graduação em Geografia - FCT
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The Lavra Velha gold prospect is located in Ibitiara city, in the Espinhaço Setentrional physiographic domain, on the west edge of Chapada Diamantina – central part of Bahia. It is inserting on Gavião Block, a compartment of São Francisco Cráton (Almeida, 1977). The Lavra Velha gold dump is formed by an association of hydrothermal breccia lodged in acid and intermediate rocks, classifying in tonalite, granodiorite and diorite, with high alteration, cut off by a vein and venules system constituted by hydrothermal association composed by hematite, tourmaline, quarz and sericite, located in the north limit of Ibitiara granite. In the regional geological context the area is represented by Archaean rocks (Paramirim Complex) and Paleoproterozoic rocks (Ibitiara granitoid and Matinos Granite) constituted the basement, following by paleo to mesozoic pluton-vulcanic-sedimentary association of Rio dos Remédios Group, intruded by mafic rocks. It was used geochemistry and petrographic analysis compiling to field works data to characterize the rocks where the gold mineralization is inserting. Previously these rocks were classifying in volcanic rocks of Novo Horizonte Formation. Developing this monograph’s work the petrogenetic characteristics suggesting that these rocks called volcanic actually belong to Ibitiara granitoid as a portion more metamorphosed. The green schist is the predominant metamorphism in the area with low deformation, associated to high concentration of fluid circulating. The hydrothermal alteration is the process responsible for rocks modifications and strong sericitization generalize
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The study area of the Guarda-Mor target (Israelândia-GO) contextualizes the terrains of the estaern portion of the Arenópolis Magmatic Arc, more accurately, the Neoproterozoic associations inserted in the field of the Jaupaci volcano-sedimentary sequence. The mapped area is located in the central-western of Goiás state. The presente paper has as main objective to characterize the structural, petrographic and litogeochemistry of the target rocks beyond to compare these factors with the Mina Bacilândia rocks (Fazenda Nova-GO) in order to assess the genetic similarity of volcano-sedimentary units and deposits associated. The Guarda-Mor target is represented by the Jaupaci metavolcanic rocks sequence presenting bimodal volcanism. This sequence consists in metafelsic rocks like sericite/muscovite quartz schist, phyllite and metarriolites and/or metariodacites with calc-alkaline geochemical signature and metamafic rocks with tholeiitic character formed by actinolite - chlorite schist and chlorite - quartz schist. Besides the package of supracrustal rocks also can be observed the occurrence of a local intrusion syn- to late - tectonic named Granito Subvulcânico. In the study area beyond the marked volcanism also seen an event of crustal melting granitogênese evidenced by the presence of 2 granites at the east and the west of the map, Granito Israelândia and Granito Iporá respectively. Structural analysis both at the macro and micro have identified 3 deformation phases. The types of rock on the region record features in the metamorphic facies top and down. These features were subdivided into 3 metamorphic areas: the east and West areas show thermal metamorphism due to intrusion of adjacente granites while the central domain displays features of regional metamorphism. Gold mineralization of the Guarda –Mor deposit target suggests a possible structural control beyond pronounced the hydrothermal alteration. The mineralization may also be...
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Pós-graduação em Geociências e Meio Ambiente - IGCE