Quantitative compositional analysis of martian mafic regions using the MEx/OMEGA reflectance data

The Mars Express Observatoire pour Mineralogie, I'Eau, les Glaces et I'Activite (OMEGA) collected in Unprecedented visible and near-infrared hyperspectral dataset covering the low albedo regions of Mars. We investigate the ability to infer modal abundance of surfaces of these regions from a radiative transfer model developed by Shkuratov et al. [Shkuratov. Y., Starukhina, L., Hoffman, H., Arnold, G., 1999. Icarus 137, 235-246] and adapted to basaltic surfaces by Poulet and Erard [Poulet F., Erard, S., 2004. J. Geophys. Res. 109 (E2), doi: 10.1029/2003JE002179]. From OMEGA measurements of mafic surfaces, we develop several sensitivity tests to assess the extent to which the model call he applied to predict pyroxene composition (high-calcium phase and low-calcium phase), abundance of almost neural components (plagioclase) in the near-infrared wavelength as well as grain sizes, by Using a library of selected end-members. Results of the sensitivity tests indicate that the scattering model call estimate both abundances and grain sizes of major basaltic materials of low albedo regions within uncertainties (+/- 5 to 15 vol%). The model is then applied to data from dissected cratered terrains located in Terra Mendiani. The derived grain size including uncertainties is in the 50-500 mu m range. This is consistent with the thermal inertia and albedo of this region, which indicates a fine sand-sized surface with little dust. The abundances of plagioclase (43-57%) and pyroxenes (35-45 +/- 10%, including 11 +/- 5% of low-calcium phase) are in good agreement with previous basalt-like compositions of low albedo regions from thermal infrared spectral measurements. The method presented in this paper Will provide a valuable tool for evaluating the modal mineralogy of other mafic regions of Mars Observed in the near-infrared wavelength range. (c) 2008 Elsevier Inc. All rights reserved.