Alteration Mapping for Porphyry Copper Exploration Using ASTER and QuickBird Multispectral Images, Sonajeel Prospect, NW
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RESEARCH ARTICLE
Alteration Mapping for Porphyry Copper Exploration Using ASTER and QuickBird Multispectral Images, Sonajeel Prospect, NW Iran Zahra Yazdi1 • Alireza Jafari Rad1
•
Mehraj Aghazadeh2 • Peyman Afzal3
Received: 1 February 2017 / Accepted: 16 July 2018 Ó Indian Society of Remote Sensing 2018
Abstract The Sonajeel prospect is located in the Arasbaran belt which is one of the significant copper mineralization belts in NW Iran. There are mostly Eocene volcano-sedimentary rocks and Post Eocene intrusive units which are the source for mineralization in the area. ASTER multispectral images were used for delineation of alteration zones as a key feature of porphyry copper mineralization. Due to the need for geometric correction and ortho-rectification of the ASTER images, a high resolution QuickBird image with pixel width of about 60 cm (in PAN) was employed as a reference image in order to boost the rectification process. Ortho-rectification has been done by using digital elevation model which is created by topographic map in scale 1:1000. Potassic alteration as one of the essential alteration types in porphyry copper deposits, distributed mostly in the north of the Sonajeel prospect that determined by Thermal infrared bands processing. Phyllic and argillic alteration zones detected by creating relative absorption band-depth grids which are comparable to field observations. Moreover, silica rich areas which are remnants of hydrothermal circulation and form at the top of porphyry copper systems were detected for recognition of epithermal deposits (with 1 km distance from Sonajeel porphyry system). Finally, Remote Sensing results were compared by field evidences especially for determination of an epithermal system. Most parts of the alteration zones were observed of the surface confirmed with the remote sensing alteration (in average about 75% matched fittingly), displayed concentrations anomalous in the NE and NW parts of the studied area. Keywords Porphyry copper mineralization Epithermal gold–copper system Hydrothermal alteration zones ASTER QuickBird Sonajeel prospect
Introduction
& Alireza Jafari Rad [email protected] Zahra Yazdi [email protected] Mehraj Aghazadeh [email protected] Peyman Afzal [email protected] 1
Department of Geology, Science and Research Branch, Islamic Azad University (IAU), Tehran, Iran
2
Department of Geology, Payame Noor University, Tabriz, Iran
3
Department of Mining Engineering, South Tehran Branch, Islamic Azad University (IAU), Tehran, Iran
Due to the effects of hydrothermal fluids, hosting environments of porphyry copper deposits (PCDs) have broad alteration patterns including potassic, phyllic (sericitic), argillic, and propylitic. These expansive signatures are the most applicable tools in PCD exploration (Sillitoe 2010; Alimohammadi et al. 2015). Multispectral images have strong capabilities and wide applications in mineral exploration progress especially at reconnaissance and prospecting stages. Among their benefits, detecting alteration
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