Application of ET~ image in detecting alteration halosand discriminating lithological units in Mianeh (eastAzarbayjan)

The alka line and calc-alkaline volcanic activities in Mianch have reactivated the hydrothermal so lutions, resulting in the fonnation of epithermal mineralization in the region. The mineralized zone trending NWSE, and has been affected by NE-SW bended and folded structures. The precious and base metals mineralization are confined to structurally hended zone. Landsat-7(ETMJ data were used to study the alteration zones, structural features and to discriminate the lithological units in the region. The primary corrections were carried out on the images and the data resampled to 1 Sm. Based on spectral pattern of minerals present in the alteration system, such as chlorite, epidote, kaolinite, jarosite, geotite, hydrothermal alteration zones of the area were detected using band ratio and principle component analysis (PCA) techniques, which also well correlated with field studies. The linear and ring structural features along with lithological units were discriminated based on spectral features of minerals. Ultimately, the study reveals that the application of PCA resulted in enhancement of alteration halos. The field checks have confinned the achievement and indicate the western part of the area as potentially promising zone.