Caracterização de ocorrência de cobre por meio de levantamento estrutural e geofísico em faixa de dobramentos na região de Caçapava do Sul (RS)
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2017-06-23
Autores
Santos, Shaiely Fernandes dos [UNESP]
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Universidade Estadual Paulista (Unesp)
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A ampla variedade de aplicações de cobre estimula a exploração de áreas mineralizadas. A prospecção de sulfetos por meio de métodos geofísicos, como a Eletrorresistividade e a Polarização Induzida (IP), são altamente promissores devido ao contraste de resistividade elétrica e cargabilidade, onde depósitos com sulfetos disseminados ou filoneanos são caracterizados por baixa resistividade e alta polarizabilidade. Esse trabalho realizou estudo de prospecção geofísica por meio de aquisição tomográfica em ocorrência mineral de cobre, na região de Caçapava do Sul (RS). Foram realizadas três linhas de aquisição por meio da técnica de tomografia elétrica em arranjos Dipolo-dipolo, Schlumberger e Wenner com 400 metros de comprimento e 5 metros de espaçamento entre eletrodos, dispostas de forma perpendicular à estruturação geral da área, representada com um grande sinclinal, de alta complexidade geológica e estrutural, em cuja crista foram reconhecidas galerias de pesquisa com carbonatos e sulfetos de cobre. Os resultados indicam que o arranjo dipolo-dipolo melhor realça e detalha as feições em regiões com estruturas inclinadas e fraturas. Os modelos de inversão 2D e modelamento 3D apresentam regiões centrais e laterais com alta resistividade e alta cargabilidade com indicativo de provável zona de stockwork com sulfetos alojados. Zonas periféricas com moderada resistividade e moderada cargabilidade inferem possíveis áreas com presença de argilização, zonas com alta cargabilidade e baixa resistividade são prováveis zonas de sulfetação e as possíveis zonas de silicificação com altos valores de resistividade e baixos de cargabilidade, observadas nas adjacências das prováveis zonas mineralizadas.
The wide variety of copper applications encourages the exploration of mineralized areas. Sulfide prospecting by means of geophysical methods, such as electrical resistivity and induced polarization (IP), are highly promising due to the contrast of electrical resistivity and chargeability, where deposits with disseminated sulfides or filoneans are characterized by low resistivity and high polarizability. This work carried out a study of geophysical prospecting by means of tomographic acquisition in mineral copper occurrence, in the region of Caçapava do Sul (RS). Three acquisition lines were performed by means of electrical tomography technique using a Dipole-dipole, Schlumberger and Wenner arrangements, with a length of 400 meters and a spacing of 5 meters between the electrodes, arranged in perpendicular layout to the general structure of the area, represented by a large synclinal, of high geological and structural complexity, where research galleries with carbonates and copper sulfides were recognized in the ridge. The results indicate that the dipole-dipole arrangement best highlights and details features in regions with sloped structures and fractures. The 2D inversion models and 3D modeling indicate central and lateral regions with high resistivity and high chargeability with indicative of probable stockwork zone with housed sulfides. Peripheral zones with moderate resistivity and moderate chargeability infer possible areas with presence of argilization, zones with high chargeability and low resistivity are likely to be zones of sulfation and possible silicification zones with high resistivity values and low chargeability values, observed in the vicinity of the probable mineralized zones.
The wide variety of copper applications encourages the exploration of mineralized areas. Sulfide prospecting by means of geophysical methods, such as electrical resistivity and induced polarization (IP), are highly promising due to the contrast of electrical resistivity and chargeability, where deposits with disseminated sulfides or filoneans are characterized by low resistivity and high polarizability. This work carried out a study of geophysical prospecting by means of tomographic acquisition in mineral copper occurrence, in the region of Caçapava do Sul (RS). Three acquisition lines were performed by means of electrical tomography technique using a Dipole-dipole, Schlumberger and Wenner arrangements, with a length of 400 meters and a spacing of 5 meters between the electrodes, arranged in perpendicular layout to the general structure of the area, represented by a large synclinal, of high geological and structural complexity, where research galleries with carbonates and copper sulfides were recognized in the ridge. The results indicate that the dipole-dipole arrangement best highlights and details features in regions with sloped structures and fractures. The 2D inversion models and 3D modeling indicate central and lateral regions with high resistivity and high chargeability with indicative of probable stockwork zone with housed sulfides. Peripheral zones with moderate resistivity and moderate chargeability infer possible areas with presence of argilization, zones with high chargeability and low resistivity are likely to be zones of sulfation and possible silicification zones with high resistivity values and low chargeability values, observed in the vicinity of the probable mineralized zones.
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Pesquisa mineral, Sulfeto, Resistividade elétrica, Cargabilidade, Modelamento 3D, Mineral research, Sulfide, Resistivity, Chargeability, 3D modeling