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Scientific and Technical Aerospace Reports Volume 38 July 28, 2000

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in Yellowstone National Park. We are applying recent advances in remote sensing methods to detect <strong>and</strong> map the mineralogy of<br />

active <strong>and</strong> ancient hydrothermal systems, vegetation cover types, <strong>and</strong> hot springs microorganisms. These maps will be used to<br />

increase the underst<strong>and</strong>ing of the hydrothermal systems <strong>and</strong> to examine the links between the distribution of plant species <strong>and</strong><br />

large mammal populations (specifically, the use of whitebark pine by grizzly bears). This paper presents the initial results of our<br />

efforts in mapping biology <strong>and</strong> mineralogy in Yellowstone National Park using imaging spectroscopy.<br />

Author<br />

Yellowstone National Park (ID-MT-WY); Thematic Mapping; Mineral Deposits; Remote Sensing; Imaging Spectrometers; Spectroscopy<br />

<strong>2000</strong>0064554 Analytical Imaging <strong>and</strong> Geophysics, LLC, Boulder, CO USA<br />

Mapping Active Hot Springs Using AVIRIS <strong>and</strong> TIMS<br />

Kruse, F. A., Analytical Imaging <strong>and</strong> Geophysics, LLC, USA; Summaries of the Seventh JPL Airborne Earth Science Workshop<br />

January 12-16, 1998; Dec. 19, 1998; <strong>Volume</strong> 1, pp. 255; In English; See also <strong>2000</strong>0064520; No Copyright; Abstract Only; Available<br />

from CASI only as part of the entire parent document<br />

This research is studying the occurrence <strong>and</strong> characteristics of both active <strong>and</strong> fossil hot springs systems using Thermal<br />

Infrared Multispectral Scanner (TIMS) <strong>and</strong> Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data to provide insights<br />

into the origins of hydrothermal systems <strong>and</strong> precious metal ore deposits. At Steamboat Springs, Nevada, TIMS delineates the<br />

silica sinter associated with active alkaline-type hot springs, while AVIRIS data map alteration minerals including alunite, kaolinite,<br />

<strong>and</strong> hydrothermal silica associated with inactive acid-sulfate hot springs. Sites studied at Yellowstone National Park, Wyoming,<br />

include Mammoth Hot Springs, consisting of several ages of travertine terraces as well as glacially-transported travertine<br />

material. Hot springs in the Firehole River basin, include active hydrothermal areas associated with the Upper, Midway, <strong>and</strong> Lower<br />

geyser basins, with mineralogy characteristic of the both the alkaline <strong>and</strong> acid-sulfate type hot springs, including hydrothermal<br />

silica, alunite, <strong>and</strong> kaolinite. Surface exposures in Hayden Valley <strong>and</strong> in the Norris <strong>and</strong> Gibbon Geyser Basins indicate predominantly<br />

acid-sulfate alteration, along with smaller occurrences of silica sinter. Study of the nature <strong>and</strong> spatial distribution of specific<br />

hydrothermal-alteration minerals at active hot springs using hyperspectral remote sensing provides insight into the geochemistry<br />

of these systems, <strong>and</strong> to the occurrence <strong>and</strong> characteristics of hot springs systems in the fossil record. These findings potentially<br />

could lead to new <strong>and</strong>/or improved exploration methods for epithermal ore deposits.<br />

Author<br />

Hydrothermal Systems; Infrared Imagery; Mineral Deposits; Remote Sensing; Thematic Mapping; Springs (Water)<br />

<strong>2000</strong>0064555 Analytical Imaging <strong>and</strong> Geophysics, LLC, Boulder, CO USA<br />

Spectral Identification of Image Endmembers Determined from AVIRIS Data<br />

Kruse, F. A., Analytical Imaging <strong>and</strong> Geophysics, LLC, USA; Summaries of the Seventh JPL Airborne Earth Science Workshop<br />

January 12-16, 1998; Dec. 19, 1998; <strong>Volume</strong> 1, pp. 257; In English; See also <strong>2000</strong>0064520; No Copyright; Abstract Only; Available<br />

from CASI only as part of the entire parent document<br />

Experienced scientists can easily identify materials based on their visible/infrared reflectance spectra using field or laboratory<br />

instruments. Imaging spectrometry (hyperspectral data) also allow identification of materials using spectroscopy; however, these<br />

data typically consist of hundreds-of-thous<strong>and</strong>s of spectra, so which spectra do you identify? Some researchers have taken the<br />

approach of matching every spectrum in an image to a spectral library. This works well when pure materials are present on the<br />

ground <strong>and</strong> all of the materials are contained in the library. In real-world situations, however, where materials are spatially or intimately<br />

mixed, only the strongest features are matched. In this case, it’s also not possible to have all of the possible mixtures in<br />

the library, <strong>and</strong> thus the above approach will only ”Identify” the predominant material, if any material at all. The research described<br />

here concentrates on identifying only the purest spectra extracted from the hyperspectral data. After applying data reduction <strong>and</strong><br />

endmember extraction methodologies, the endmember spectra are used in an automated identification procedure based on analysis<br />

of spectral features. This approach has an improved likelihood of success because 1) the best endmember spectra have already<br />

been extracted for analysis, 2) the extracted endmembers are mean spectra <strong>and</strong> thus have improved signal-to-noise over single<br />

spectra, 3) these spectra are typically one material (no mixing), 4) not every spectrum in the image needs to be analyzed. Once<br />

the individual endmembers have been identified, then a variety of mapping methods can be used to map their spatial distributions,<br />

associations, <strong>and</strong> abundances.<br />

Author<br />

Spectroscopy; Spectrum Analysis; Remote Sensing; Spectral Correlation; Imaging Spectrometers; Image Classification<br />

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