Mapping variations in plagioclase felspar mineralogy using airborne hyperspectral TIR imaging data

The Na-Ca chemistry of plagioclase felspar was measured and mapped remotely using airborne hyperspectral thermal infrared (TIR) SEBASS image data collected from a well-exposed porphyry system near Yerington, Nevada. This followed correction of the airborne SEBASS data for instrument and atmospheric effects and temperature-emissivity separation and was validated through associated field and laboratory studies. The later found a linear correlation between the relative intensities of the plagioclase /spl mu/FTIR emissivity spectral features at 9.6 and 10.0 /spl mu/m and the XRD dspacing of the felspar 111/130 hkl reflection, both of which are sensitive to the Na-Ca chemistry of plagioclase. The SEBASS derived felspar mineralogy maps clearly show variations in Na-Ca plagioclase felspar chemistry related to the nature of the host rock and any superimposed hydrothermal alteration.