Hematite, pyroxene, and phyllosilicates on Mars: implications from oxidized impact melt rocks from Manicouagan Crater, Quebec, Canada

Visible and near-IR reflectivity, Mossbauer, and X-ray diffraction data were obtained on powders of impact melt rock from the Manicouagan Impact Crater located in Quebec, Canada. Manicouagan data are consistent with previous assignments of hematite and pyroxene to the ~850 and ~1000 nm bands observed in Martian reflectivity spectra. Manicouagan data also show that possible assignments for intermediate band positions (900-920 nm) in Martian spectra are pyroxene and/or hematite-pyroxene assemblages. By analogy with impact melt sheets and in agreement with observables for Mars, oxidative alteration of Martian impact melt sheets above 205°C and subsequent erosion could produce rocks and soils with variable proportions of hematite, pyroxene, and phyllosilicates as iron-bearing mineralogies. -from Authors