Estudo de mineralizações de tipo Cu-porfiro do sul do Peru por meio de sensoriamento remoto e aeromagnetometria

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

A large number of mineral deposits are known in the Andes, including Cu-porphyry deposits. Among these, Cuajone, Quellaveco and Toquepala are some of the most important in the southern portion of Peru. They are located in the domain ofthe Bolivian Orocline, within the Incapuquio shear zone, a structure that controls the mineralization, ofabout 60 Ma. Airborne magnetic data, multispectral remote sensing images and reflectance spectroscopy were employed in order to characterize the Cu-porphyry deposits of southern Peru. The objective was to contribute toward the understanding ofthe geological characteristics of these deposits and to assess the use of remote sensing and low resolution geophysical data for regional exploration in the Andes. Airborne geophysics indicated that distensional structures of E- W direction control the occurrence of ore bodies, in association with the regional transpressive tectonics in the NW -SE direction. The mineralization occur on a continental crust 60 km deep, associated with magnetic intensities in the range 0-70 nT, which are interpreted as being caused by the loss of magnetization by ferromagnetic minerals due to heating processes linked to the emplacement of igneous intrusions and tectonic movements. The use of multispectral remote sensing data led to the spectral characterization of hydrothermal alteration haloes associated with the Cu-porphyry deposits, revealing their mineral zoning. It also enabled the identification of a spectrally anomalous area, very similar to the mineralized ones, hereby named Alvo Sul. To achieve these results, image processing techniques were employed in order to extract the spectral information related to the mineral assemblages typical of hydrothermal alteration processes, such as phyllic and argillic, despite the low spectral resolution of Landsat-TM. Reflectance spectroscopy in the SWIR allowed the detailed identification of minerals produced by hydrothermal alteration, such as illite 2-M, that was useful as an indicator of alteration zoning in the Quellaveco deposit The results obtained testify the importance and viability of the integrated use of airborne geophysical data and remote sensing in order to define potential areas for Cu porphyry in the Andes

ASSUNTO(S)

cobre sensoriamento remoto alteração hidrotermal andes região

ACESSO AO ARTIGO

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