Identification of alterations related to porphyry polymetallic mineralization in Qarah Gol area (Ardabil Province) using principal component analysis and spectral angle mapping

Qarah Gol area is located in Ahar-Arasbaran metallurgical zone in Ardabil Province, Meshkinshahr city in Moradloo section. The oldest rock units in the study area are related to the Cenozoic (Eocene), which consists of volcanic breccia. In this area, microquartzdiorite have penetrated into volcanic and pyroclastic rocks and alteration and mineralization have taken place on a weak scale. The results of Aster image processing, using absorption bands and selection of the best ratio color composite (5 + 7.6, 9.8, 4.5) respectively for the detection of argillic, phyllic and propylitic alterations, as well as using techniques such as principal component analysis and spectral angle mapping indicate that associated alterations in the central part of this deposit is consistent with petrographic studies in Qarah Gol area. Field studies have shown that the results of Spectral Angle Mapper (SAM) have performed better than the principal component analysis (PCA) in the detection of alterations.