Hydrothermal alteration mapping using ASTER data, Takab-Baneh area, NW Iran: a key for further exploration of polymetal deposits

A large number of polymetallic deposits exist in the Takab-Baneh area, NW Iran. Different methods such as minimum noise fraction (MNF), pixel purity index (PPI), n-D visualization, mixture tuned matched filtering (MTMF), relative absorption band depth (RBD), band ratio (BR), and principal component analysis (PCA) were used for extraction of alteration zone characteristics from ASTER data in the Takab-Baneh area. The overall accuracy of MTMF is around 97% for phyllic, and 98% for argillic propylitic, which validates the potential and suitability of ASTER imagery for classification of alteration type. Subsequently, the alteration maps were confirmed by ground-truthing, i.e., field observation and petrographic studies. The results show a wide distribution of three main phyllic, argillic and propylitic alteration zones, that can be considered as targets for future exploration in NW Iran.