Digital Image Processing and Analysis Techniques for Detection of Hydrothermal Alteration Zones: A Case Study in Siah-Ja
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RESEARCH ARTICLE
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 Zahra Mokhtari & Mohammad Boomeri & Sasan Bagheri
Received: 21 January 2014 / Accepted: 5 October 2014 # Indian Society of Remote Sensing 2015
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 SiahJangal 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.
Keywords Alteration zones . ETM+ . Band ratio . Colour composite . Principal component analysis . Iran
Z. Mokhtari (*) : M. Boomeri : S. Bagheri Department of Geology, Faculty of Sciences, University of Sistan and Baluchestan, Zahedan, Iran e-mail: [email protected]
Introduction Iran is comprised of many tectono-stratigraphic domains with different structural and petrological features. According to Berberian and King (1981) major lithotectonic units of Iran are: 1) Zagros Fold Belt, 2) Sanandaj–Sirjan Zone, 3) Sahand– Bazman Belt, 4) Central Iran, 5) Lut Block, 6) Alborz Zone, 7) Kopeh Dagh zone, 8) Eastern Iran suture zone (Flysch zone), 9) Makran zone (Fig. 1). The Siah-Jangal area is located in north of the Mount Taftan, southeastern Iran. The Mount Taftan is composed of Quaternary volcanic rocks of Makran volcanic belt. This volcanic belt extends through an E-W belt developed from the Bazman volcano in Iran to Koh-i-Sultan in Pakistan and made a classic magmatic arc parallel to the Makran Zone (Northern Makran magmatic Arc or NMA). NMA is shown in Fig. 2. The NMA was formed by subduction of Oman oceanic crust under southern margin of the Makran zone (Farhoudi and Karige 1977; Berberian et al. 1982). This subduction zone can be introduced as Makran subduction zone. The NMA to th
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