Integração de dados geofísicos e geológicos na caracterização morfológica de ocorrência de cobre na borda norte da Bacia do Camaquã (RS)

• Autor(a) principal: Côrtes, Ariane Raissa Pinheiro [UNESP]
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/138496; http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/03-05-2016/000864251.pdf
• topic: Geophysics; Geofisica; Cobre; Geologia estrutural

In a scenario where the discovery of high tonnage and low volume deposits are increasingly scarce through geochemical prospecting and geological detailing of the surface, current and future perspectives in mineral exploration should consider the increasing use of geophysical methods as a fundamental tool for research of deep deposits, not susceptible to the action weathering processes. This work shows the results of the joint application of DC resistivity and induced polarization methods integrated with geological and structural data in potentially mineralized area with copper sulfides, located on the northern edge of the Camaquã Basin (RS). This mineral occurrence is hosted in silicified and fractured metarenite, characterized by the abundant presence of malachite and azurite as disseminations or impregnations in the rock weakness planes. Six lines were acquired in a Wenner-Schlumberger arrangement through the electrical imaging technique, with 510 m length for each row and spacing of 10 m between electrodes. The structural survey included mainly measures of fractured metarenites of Passo da Promessa Formation (Maricá Group) and Vacacaí metamorphic Complex's quartzites. The low sulphidation epithermal model is adopted as analogous to the mineralization, considering the relationship with the geological and geophysical data obtained for the area, in the absence of chemical analysis of soil or rock. The results indicate a low resistivity and high chargeability zone at 60 m depth associated with a sulphide zone with 100 m of length and elongated in the direction N55W. High resistivity and low chargeability zones are surrounding the sulphide zone, which are related to silicification areas. Finally, zones presenting medium to high resistivity and high chargeability indicate continuity at depth of the silicified metarenite of the mineral occurrence, with gradatively higher concentrations of metallic sulfides toward the sulphide zone. The...