Digital Image Processing and Analysis Techniques for Detection of Hydrothermal Alteration Zones: A Case Study in Siah-Jangal Area, North of Taftan Volcano, Southeastern Iran

Abstract

Hydrothermal alteration zones have significant role in prospecting of porphyry mineral deposits. In this research, Image processing techniques were applied on the digital subset ETM + data covered the Siah-Jangal area. These techniques generated several products of enhanced satellite imagery, such as colour composite images, ratio images and principal component analysis images. These techniques have been successfully used in mapping of hydrothermal alteration and mineralization zones in the study area. The colour composite and band ratio methods show very clearly the hydrothermal altered zones of clay minerals and iron oxides in and around the Siah-Jangal area. The principal component analysis using the Crosta technique also enabled us to represent undoubtedly the altered hydroxyl and iron-oxide mineral zones as well. The Crosta method has been used on selected 6 (standard method of PCA), 4 and 3 bands. There is no significant difference of the hydroxyl images in the Band ratio and PC methods. But the best results, in terms of mapping the distribution of iron oxide alteration, were obtained using the band ratio and Crosta methods on 3 bands. The results indicate that methods is promising for identifying alteration zones and can assist exploration geologists to find new prospects of porphyry copper and gold deposits in the other virgin regions before costly detailed ground investigations.