Skip to main content
U.S. flag

An official website of the United States government

Thermal infrared (2.5-13.5 μm) spectroscopic remote sensing of igneous rock types on particulate planetary surfaces

January 1, 1989

Fundamental molecular vibration bands are significantly diminished by scattering. Thus such bands in spectra of fine particulate regoliths (i.e., dominated by <5-μm particles), or regoliths displaying a similar scale of porosity, are difficult to use for mineralogical or rock type identification. Consequently, other spectral features have been sought that may be more useful in spectroscopic remote sensing of composition. We find that mineralogical information is retained in overtones and combination tones of the fundamental molecular vibrations in the 3.0- to 7.0-μm region, but that relatively few minerals have a sufficiently distinctive band structure to be unambiguously identified with currently available techniques. More significantly, identification of general rock type, as defined by the SCFM chemical index (SCFM = SiO2/SiO2 + CaO + FeO + MgO), is possible using spectral features associated with the principal Christiansen frequency and with a region of relative transparency between the Si-O stretching and bending bands. However, environmental factors may affect the appearance and wavelengths of these features. Finally, prominent absorption bands may result from the presence of relatively small amounts of water, hydroxyl or carbonate, because absorption bands exhibited by these materials in the 2.7- to 4.0-μm region, where silicate spectra are otherwise featureless, increase strongly in spectral contrast with decreasing particle size. Such materials are thus detectable in very small amounts in a particulate regolith composed predominantly of silicate minerals.

Citation Information

Publication Year 1989
Title Thermal infrared (2.5-13.5 μm) spectroscopic remote sensing of igneous rock types on particulate planetary surfaces
DOI 10.1029/JB094iB07p09192
Authors John W. Salisbury, Louis S. Walter
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Geophysical Research
Index ID 70016051
Record Source USGS Publications Warehouse