Mapping of hydrothermal alteration in the Cuprite mining district, Nevada, using aircraft scanner images for the spectral region 0.46 to 2.36µm

摘要: Color composites of Landsat Multispectral Scanner ratio images that display variations in the intensity ferric-iron absorption bands are highly effective for mapping limonitic altered rocks but ineffective nonlimonitic rocks. Analysis 0.45- to 2.5-µm field and laboratory spectra shows iron-deficient opalized Cuprite mining district, Nevada, have an intense OH-absorption band near 2.2 µm, owing their content clay minerals alunite, this spectral feature is absent or weak adjacent unaltered tuff basalt. Altered district can be discriminated from with few ambiguities by use color-ratio composite derived multispectral (0.46 2.36 µm) aircraft data. In addition, some effects mineralogical zoning within area. Only amounts limonite discerned shorter wavelength data, bands, color aerial photographs.