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Effects of pure silica coatings on thermal emission spectra of basaltic rocks: Considerations for Martian surface mineralogy
Author(s) -
Kraft Michael D.,
Michalski Joseph R.,
Sharp Thomas G.
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2003gl018848
Subject(s) - martian surface , silicate , materials science , basalt , mineralogy , amorphous solid , substrate (aquarium) , weathering , mars exploration program , spectral line , martian , geology , astrobiology , chemical engineering , geochemistry , chemistry , physics , oceanography , organic chemistry , astronomy , engineering
On Mars, silica derived from chemical weathering could precipitate to coat rocks and particles. We suggest that rock coatings of secondary amorphous silica may account for a widespread Martian surface spectral unit previously modeled as andesite or weathered basalt. In a laboratory study, we investigated the effects of synthetic silica coatings on thermal infrared (TIR) spectroscopic measurements. Secondary amorphous silica is spectrally similar to silicate glass and clay spectra used in previous spectroscopic models. Silica coating and substrate spectra combine nonlinearly to produce a composite spectrum of a coated rock. Silica coatings <10 μm thick effectively mask the spectral contribution of a silicate substrate. Therefore, the capability of volumetrically small amounts of silica present as thin coatings on rocks should be considered when seeking explanations for spectral variability of Martian surface materials.