Airborne hyperspectral surveying as a tool for mineral exploration at high latitudes: a pilot study over porphyry Cu deposits, eastern Alaska Range, Alaska
Graham GE, Kokaly RF, Kelley KD, Hoefen TM, Johnson MR, Hubbard BE. Airborne hyperspectral surveying as a tool for mineral exploration at high latitudes: a pilot study over porphyry Cu deposits, eastern Alaska Range, Alaska. In The 14th Society for Geology Applied to Mineral Deposits Biennial Meeting (SGA) "Mineral Resources to Discover". Quebec City, Canada. August 20-23, 2017. S08 - From fertility to footprints: New vectoring tools for mineral exploration. S08 - From fertility to footprints: New vectoring tools for mineral exploration
The U.S. Geological Survey collected airborne imaging spectrometer data over unmined porphyry Cu deposits in the eastern Alaska Range using the HyMap2™ sensor in 2014. The objective was to test whether this technology could aid regional mineral exploration efforts in rugged remote parts of the State. Maps of the distributions of predominant minerals, made by matching reflectance signatures in HyMap2™ data to reference spectra in the shortwave infrared region, do not uniquely discriminate individual rock units but do identify hydrothermal alteration associated with porphyry deposits and prospects hosted mostly within the Nabesna pluton. In the footprints of porphyry Cu deposits at Orange Hill and Bond Creek, unique spectral signatures are related to variations in chlorite and muscovite abundance and their chemical composition. This is best revealed by variations in 2.2 μm Al-OH absorption feature positions in pixels spectrally dominated by muscovite. Electron microprobe analyses confirm that these longer wavelength 2.2 μm absorption features are the result of chemical differences in micas spatially associated with the porphyry deposits. The same chlorite classifications and absorption feature positions also delineated new mineral occurrences. Our study suggests that airborne imaging spectroscopy has application for regional mineral exploration in mountainous terrain in Alaska.
- Type
- Conference Proceeding Paper
- Authors
- Graham, Garth; Kokaly, Raymond; Kelley, Karen; Hoefen, Todd; Johnson, Michaela; Hubbard, Bernard
- Units
- WRST
- Keywords
- airborne imagery, Alaska, mineral exploration, spectrometer data, spectroscopy