Espectroscopia de reflectancia aplicada al estudio de depósitos polimetálicos de Pb, Zn, Cu ± Ag ± Au del sur de la Sierras de Córdoba, Argentina

MAFFINI, MARÍA NATALIA; DUCART, DIEGO FERNANDO; CONIGLIO, JORGE ENRIQUE; D'ERAMO, FERNANDO JAVIER; MOREIRA SILVA, ADALENA; DEMARTIS, MANUEL; BEMFICA TOLEDO, CATARINA; PINOTTI, LUCIO PEDRO

Joao Pessoa

Simposio; XVII Simposio Brasileiro de Sensoramiento Remoto; 2015

Instituto Nacional de Pesquisas Espaciais

This paper describes the application of spectral and magnetic analysis techniques in hydrothermal alteration zones related to polymetallic deposits, in the Sierras de Córdoba (Argentina). The sampling for spectral analysis was carried out in two key study areas and it involved several mineralized structures. The mineralization occurs as discordant tabular veins, mainly composed of quartz with variab le contents of sulfides and Au-Ag minerals. Hydrothermal alteration of the metamorphic host rocks is conspicuous, being the phyllic alteration the most distributed along the structures. The spectral analysis results revealed notable differences between the altered host rocks and their non-altered protholiths. In the alteration zones there is an increase in the abundance of white micas and its crystallinity, however, at the same time the rocks show lower magnetic susceptibility values. One of the most oustanding result is the variation in the composition of illite in some mineralized structures, from normal potassic to phengitic. The spatial distribution of phengitic illite is genetically related with the physicochemical characteristics of the hydrothermal fluids, in the study areas its occurrence is restricted to the most mineralized metallotects. The application of spectral analysis in polymetallic veins has not been mentioned in the Sierras Pampeanas. However, this study reveals considerable advantages of the method, allowing the rapid identification of hydrothermal mineral associations, variations of parameters of composition and abundance and differenciation of several types of fine grain minerals. Therefore the spectral and magnetical data can have considerable importance for the characterization of hydrothermal alteration zones in this type of mineral deposits.