White mica wavelength position map for Nabesna, Alaska, derived from imaging spectrometer reflectance data
WhiteMicaWavelengthPositionMap
Dates
Publication Date
2018-02-09
Start Date
2014-07-14
End Date
2016-07-21
Last Revision
2018-10-22
Citation
Kokaly, R.F., Johnson, M.R., Graham, G.E., Hoefen, T.M, Kelley, K.D., and Hubbard, B.E., 2018, Imaging spectrometer reflectance data, mineral predominance map, and white mica wavelength position map, Nabesna Quadrangle, Alaska (ver. 1.1, October 2018): U.S. Geological Survey data release, https://doi.org/10.5066/F7NV9H6F.
Summary
A map of the wavelength position of the white mica 2,200 nanometer (nm) Al-OH absorption feature was compiled for a region of Nabesna, Alaska, using HyMap™ reflectance data provided and described in this data release. White mica wavelength position was computed for each pixel with spectrally predominant muscovite or illite. The computation was made using a function of the USGS PRISM (Processing Routines in IDL for Spectroscopic Measurements) software (Kokaly, 2011), programmed in Interactive Data Language (IDL; Harris Geospatial Solutions, Broomfield, Colorado). The PRISM function applies linear continuum-removal (Clark and Roush, 1984) to the 2,200 nm feature and fits a parabola to three channels: the channel with the minimum value [...]
Summary
A map of the wavelength position of the white mica 2,200 nanometer (nm) Al-OH absorption feature was compiled for a region of Nabesna, Alaska, using HyMap™ reflectance data provided and described in this data release. White mica wavelength position was computed for each pixel with spectrally predominant muscovite or illite. The computation was made using a function of the USGS PRISM (Processing Routines in IDL for Spectroscopic Measurements) software (Kokaly, 2011), programmed in Interactive Data Language (IDL; Harris Geospatial Solutions, Broomfield, Colorado). The PRISM function applies linear continuum-removal (Clark and Roush, 1984) to the 2,200 nm feature and fits a parabola to three channels: the channel with the minimum value in continuum-removed reflectance and one channel on either side (Kokaly, 2011). PRISM uses the wavelength position of the axis of symmetry from the fitted parabola as the definition of wavelength value. The white mica wavelength values were output as a classification image, with classes in 1-nm (0.001-micron) increments.
REFERENCES
Clark, R.N., and Roush, T.L., 1984, Reflectance spectroscopy: Quantitative analysis techniques for remote sensing applications: Journal of Geophysical Research: Solid Earth, v. 89(B7), p. 6329-6340.
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/.
The imaging spectrometer data were collected and processed as one component of a U.S. Geological Survey (USGS) mineral resource project with the goals of enhancing geologic mapping and developing methods to identify and characterize mineral deposits elsewhere in Alaska. Hyperspectral surveying is one method that can be used to rapidly acquire information about the distributions of surficial materials, including different types of bedrock and ground cover.
