Tracking Mine Waste and Mineralization in western India using imaging spectroscopy
Updated: Feb 25, 2019
Airborne remote sensing and field work are being combined to examine the effects of mining in the Indian states of Gujurat and Rajasthan.
Dr. Farrand is the PI on an investigation into effects on water quality in waters coming from a pair of mines, and their surrounding drainage basins, in western India. The study areas are the Ambaji and Zawar mines in the Indian states of, respectively, Gujurat and Rajasthan. The Ambaji site is an abandoned copper mine that is situated in Precambrian-aged metasediments and metavolcanics of the Delhi Supergroup. Sulfide mineralization at Ambaji is hosted by hydrothermally altered felsic metavolcanics rocks with ferric oxide and oxyhydroxide as well as copper carbonate surface indicator minerals. The Zawar zinc mine is an active mine that is part of the Precambrian Aravalli Supergroup and lies amidst surface exposures of dolomites and quartzites. Hyperspectral visible through short-wave infrared (VSWIR) data from the Airborne Visible/Infrared Imaging Spectrometer Next Generation (AVIRIS-NG) was collected in February 2016 over these sites as part of a joint campaign between NASA and the Indian Space Research Organization (ISRO). The AVIRIS-NG data is being used to detect, map, and characterize surface mineralogy in the area. A comprehensive mineral mapping is being carried out using the USGS Material Identification and Characterization Algorithm (MICA) software hosted on the IDL/ENVI platform. Results of the mineral mapping have been field checked and rock and soil samples were collected and are being examined for heavy and trace metal contamination. Past studies by other researchers have shown changes in the shape of the 2.2 micron Al-OH vibrational overtone feature as well as in blue-red spectral ratios that were directly correlated with the concentration of heavy and trace metals that had been adsorbed into the structure of surface minerals. Early analysis of the Zawar area scenes indicates the presence of Al-OH clay minerals which might have been affected by the adsorption of trace metals. Scenes from the Ambaji area have more extensive surface exposures of ferric iron - bearing minerals. Future work will focus more closely on detailed spectral feature mapping of absorption features that have been affected by heavy and trace metal adsorption .