2002), Effects of glass content and oxidation on the spectra of SNC-like basalts: Applications to Mars remote sensing

[1] We have investigated the effects of crystallization and oxidation on the visible and near-infrared (VISNIR) and mid-infrared (mid-IR) spectra of materials with a Shergotty-Nakhla-Chassigny (SNC) basaltic composition in order to investigate potential links between Martian VISNIR spectra, Martian mid-IR spectra, and SNC meteorite data. SNC basalt samples of varying crystallinities were synthesized and subsequently oxidized in air at 700C for 1–7 days, and reflectance spectra of both fine (75 mm) and coarse (75–500 mm) basalt samples were obtained before and after oxidation. The effects of crystallization on the spectral properties are readily observed in the unoxidized products. In the VISNIR, increasing crystallization is accompanied by an increasing influence of pyroxene absorptions and decreasing influence of glass absorptions. In the mid-IR, changes in spectral properties with crystallization are due to the variations in relative amounts of glass, pyroxene, and plagioclase. Oxidation alters the glass and pyroxenes within the samples, leading to changes in VISNIR and mid-IR spectral shapes, although distinct signatures of oxidation products are not always observed. Both spectral and electron microscopy data indicate that hematite is the dominant oxidation product in the pigeonite and glass of the samples. In pigeonite, hematite is present in nanophase form and leads to the diminishment of the diagnosti