ASTER Data Analysis for Mineral Potential Mapping Around Sawar-Malpura Area, Central Rajasthan
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RESEARCH ARTICLE
ASTER Data Analysis for Mineral Potential Mapping Around Sawar-Malpura Area, Central Rajasthan B. K. Bhadra & Suparn Pathak & G. Karunakar & J. R. Sharma
Received: 24 February 2012 / Accepted: 27 September 2012 / Published online: 1 November 2012 # Indian Society of Remote Sensing 2012
Abstract Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) SWIR bands are used in identification of alteration zones which have developed during hydrothermal activity. Among the available methods of hyperspectral data analysis, PCA and RBD techniques are found to be useful in delineation of clay alteration and iron oxide zones. ASTER data analysis by PCA and RBD of (B5+B7)/ B6 shows delineation of two distinct alteration zones with characteristic mineral assemblages viz. propylitic zone (chlorite, epidote, montmorillonite and calcite) and phyllic zone (illite, kaolinite, white mica and quartz). Iron oxide rich zones (gossans) have been delineated using ASTER band ratio technique (B2/ B1). Geochemical dispersion of soil samples shows that Pb and Zn concentration is higher in phyllic and propylitic zones around Sawar and Malpura area respectively. Thus, ASTER data shows the potential in discrimination of metasedimentary rocks and delineation of alteration zones for targeting base metals around Sawar-Malpura area in central Rajasthan.
B. K. Bhadra (*) : S. Pathak : J. R. Sharma Regional Remote Sensing Centre (West), NRSC/ISRO, CAZRI Campus, Jodhpur 342003, India e-mail: [email protected] G. Karunakar Hindustan Zinc Ltd, Udaipur 313004, India
Keywords ASTER . Principal Component Analysis (PCA) . Relative absorption-Band Depth (RBD) Ratio . Clay Alteration zones . Geochemical Analysis
Introduction Multispectral as well as hyperspectral satellite data are used to identify a variety of rocks and minerals viz. OH-bearing minerals, carbonates, sulphates, olivines, pyroxenes, iron oxides and hydroxides (Gupta 2003; Rowan and Mars 2003; Zhang and Pazner 2007; Liu et al. 2011). However, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data with specific bands are suitable for detecting iron oxides in VNIR band (0.4–1.0 μm), hydroxidebearing clay and carbonate minerals in SWIR band (0.9–2.5 μm) and silica in TIR band (8–14 μm). Hydrothermal alteration zones due to Pb-Zn-Cu sulphide mineral deposits have distinct alteration zones (Plumlee et al. 1995; Azizi et al. 2007) with a set of mineralogical assemblage viz. Propylitic Zone and Phyllic Zone. In a typical model of epithermal sulphide mineral deposit (Plumlee et al. 1995), a central argillic zone is flanked by distal phyllic and propylitic zones with decreased Cu and As abundances and increased Zn and Pb abundances. Spectral pattern of different OH-bearing clay minerals shows gradual decrease in reflectance (%) from kaolinite, montmorillonite, illite to alunite (Ranjbar et al. 2003). Thus, identification of alteration zones (iron
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oxides and clay minerals) is important in targeting any sulphide mineral deposit. Potential a
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