MineralPredominance

Citation

Hoefen, T.M, Johnson, M.R., Kokaly, R.F., Graham, G.E., Kelley, K.D., and Hubbard, B.E., 2018, Corescan© Hyperspectral Core Imager, Mark III system data collected for the characterization of mineral resources near Nabesna, Alaska, 2014-2016: U.S. Geological Survey data release, https://doi.org/10.5066/F7057DWM.

Summary

Mineral predominance data were a derivative product from the Corescan© reflectance data. Corescan Hyperspectral Core Imager Mark III (HCI-III) system data were acquired for hand samples, and subsequent billets made from the hand samples, collected during the U.S. Geological Survey (USGS) 2014, 2015, and 2016 field seasons in the Nabesna area of the eastern Alaska Range. This area contains exposed porphyry deposits and hand samples were collected throughout the region in support of the HyMap imaging spectrometer survey (https://doi.org/10.5066/F7DN435W) (Kokaly and others, 2017a). The HCI-III system consists of three different components. The first is an imaging spectrometer which collects reflectance data with a spatial resolution of approximately 500 nanometers (nm) for 514 spectral channels covering the 450-2,500 nm wavelength range of the electromagnetic spectrum (Martini and others, 2017). The second is a spectrally calibrated RGB camera that collects high resolution imagery of the samples with a 50 micrometer (μm) pixel size. The third component is a three-dimensional (3D) laser profiler that measures sample texture, surface features and shape with a vertical resolution of 20 μm (Martini and others, 2017). A total of 63 hand samples and four billets were analyzed using the HCI-III system in three scans.

The imaging spectrometer raw data was collected with an average bandpass of approximately 6 nm across the Short Wave Infrared (SWIR) but smoothing functions applied by Corescan during the conversion of raw data to reflectance result in a relative bandpass of approximately 13 nm in the data delivered to the USGS. Wavelength evaluations of the imaging spectrometer data revealed that the supplied wavelength values should be shifted and, thus, adjustments were made to the wavelength positions (Kokaly and others, 2017c). The wavelength and bandpass evaluation results are provided in the 'Calibration' section of this data release and were used to adjust the Corescan reflectance data. The calibrated Corescan data were combined into a reflectance data cube mosaic and are provided in the 'HyperspectralCalibrated' section.

Calibrated reflectance data from Corescan were processed using the Material Identification and Characterization Algorithm (MICA), a module of the USGS PRISM (Processing Routines in IDL for Spectroscopic Measurements) software (Kokaly, 2011). MICA identifies the spectrally predominant mineral(s) in each pixel of imaging spectrometer data by comparing continuum-removed spectral features in the pixel’s reflectance spectrum to continuum-removed absorption features in reference spectra of minerals and other materials. For each pixel, the reference spectrum with the highest fit value identifies the predominant mineral class.

References Cited

Clark, R.N., and Roush, T., 1984, Reflectance spectroscopy: Quantitative analysis techniques for remote sensing applications: Journal of Geophysical Research, v. 89, p. 6329–6340.

Martini, B.A., Harris, A.C., Carey, R., Goodey, N., Honey, F., and Tufilli, N., 2017, Automated Hyperspectral Core Imaging – A Revolutionary New Tool for Exploration, Mining and Research, Paper 83, Exploration 17 Integrated Earth Sciences Conference, Toronto, Canada, October 21-25, 2017, available at http://www.exploration17.com/Exploration17/media/documents/Exploration-17-Conference-Proceedings.zip.

Kokaly, R.F., 2011, PRISM: Processing routines in IDL for spectroscopic measurements (installation manual and user's guide, version 1.0): U.S. Geological Survey Open-File Report 2011–1155, 432 p., available at https://pubs.usgs.gov/of/2011/1155/.

Kokaly, R.F., Hoefen, T.M., King, T.V.V., and Johnson, M.R., 2017a, Airborne imaging spectrometer data collected for characterizing mineral resources near Nabesna, Alaska, 2014, U.S. Geological Survey Data Release, available at https://doi.org/10.5066/F7DN435W.

Kokaly, R.F., Clark, R.N., Swayze, G.A., Livo, K.E., Hoefen, T.M., Pearson, N.C., Wise, R.A., Benzel, W.M., Lowers, H.A., Driscoll, R.L., and Klein, A.J., 2017b, USGS Spectral Library Version 7: U.S. Geological Survey Data Series 1035, 61 p., https://doi.org/10.3133/ds1035.

Kokaly, R.F., Hoefen, T.M, Graham, G.E., Kelley, K.D., Johnson, M.R., Hubbard, B.E., Buchhorn, M., and Prakash, A., 2017c, Hyperspectral outcrop imaging of the Orange Hill porphyry copper deposit, Alaska, USA, paper 84, Exploration 17 Integrated Earth Sciences Conference, Toronto, Canada, October 21-25, 2017, available at http://www.exploration17.com/Exploration17/media/documents/Exploration-17-Conference-Proceedings.zip.

Contacts

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Corescan©HyperspectralData_NabesnaAK2014to2016_20181128_MINERALPREDOMINANCE.xml Original FGDC Metadata	View	33.07 KB	application/fgdc+xml
Corescan20152016_mineral_predominance_classes_and_descriptions.csv		5.78 KB	text/csv
JA0197_AK-NAB_0001_20161011000000_00_mineralpredominancemap.dat		206.64 KB	application/unknown
JA0197_AK-NAB_0001_20161011000000_00_mineralpredominancemap.hdr		6.08 KB	text/plain
JA0197_AK-NAB_0001_20161011000000_01_mineralpredominancemap.dat		206.64 KB	application/unknown
JA0197_AK-NAB_0001_20161011000000_01_mineralpredominancemap.hdr		6.08 KB	text/plain
JA0197_AK-NAB_0001_20161011000000_02_mineralpredominancemap.dat		206.64 KB	application/unknown
JA0197_AK-NAB_0001_20161011000000_02_mineralpredominancemap.hdr		6.08 KB	text/plain
JA0197_AK-SAMPLES_0001_20151002141936_mosaic_mineralpredominance.dat		1.3 MB	text/plain
JA0197_AK-SAMPLES_0001_20151002141936_mosaic_mineralpredominance.hdr		5.97 KB	text/plain
JA0197_AK-SAMPLES_0001_20151002143728_mosaic_mineralpredominance.dat		1.35 MB	text/plain
JA0197_AK-SAMPLES_0001_20151002143728_mosaic_mineralpredominance.hdr		6.01 KB	text/plain
JA0197_AK-NAB_0001_20161011000000_00_mineralpredominancemap.tfw		81 Bytes	text/plain
JA0197_AK-NAB_0001_20161011000000_00_mineralpredominancemap.tif		816.71 KB	image/geotiff
JA0197_AK-NAB_0001_20161011000000_00_mineralpredominancemap.tif.clr		1.13 KB	text/plain
JA0197_AK-NAB_0001_20161011000000_01_mineralpredominancemap.tfw		81 Bytes	text/plain
JA0197_AK-NAB_0001_20161011000000_01_mineralpredominancemap.tif		816.71 KB	image/geotiff
JA0197_AK-NAB_0001_20161011000000_01_mineralpredominancemap.tif.clr		1.13 KB	text/plain
JA0197_AK-NAB_0001_20161011000000_02_mineralpredominancemap.tfw		81 Bytes	text/plain
JA0197_AK-NAB_0001_20161011000000_02_mineralpredominancemap.tif		816.71 KB	image/geotiff
JA0197_AK-NAB_0001_20161011000000_02_mineralpredominancemap.tif.clr		1.13 KB	text/plain
JA0197_AK-SAMPLES_0001_20151002141936_mosaic_mineralpredominance.tfw		80 Bytes	text/plain
JA0197_AK-SAMPLES_0001_20151002141936_mosaic_mineralpredominance.tif		4.78 MB	image/geotiff
JA0197_AK-SAMPLES_0001_20151002141936_mosaic_mineralpredominance.tif.clr		1.13 KB	text/plain
JA0197_AK-SAMPLES_0001_20151002143728_mosaic_mineralpredominance.tfw		80 Bytes	text/plain
JA0197_AK-SAMPLES_0001_20151002143728_mosaic_mineralpredominance.tif		4.78 MB	image/geotiff
JA0197_AK-SAMPLES_0001_20151002143728_mosaic_mineralpredominance.tif.clr		1.13 KB	text/plain
mica_cmds_2micron_Corescan13nm_v1c_ADJUSTED_forrelease.mcf		85.27 KB	text/plain
mica_colors_2micron_CorescanAdjusted_v1c.txt		4.43 KB	text/plain
splib06_cv_CorescanAdjust514ch		13.46 MB	application/unknown

Purpose

HCI-III data were collected as one component of a USGS mineral resource project with the goals of enhancing geologic mapping and developing methods to identify and characterize mineral deposits elsewhere in Alaska through the use of imaging spectroscopy. HCI-III data were collected on hand samples to validate airborne HyMap imaging spectrometer results.

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