An Integrated Analysis of Martian Surface Compositions Using near Infrared through Thermal Infrared Spectroscopic Data

Introduction: A great deal has been learned about the composition of the martian surface using orbital and in-situ spectroscopy. Significant advancements have been made possible by recent measurements from the Thermal Emission Spectrometer (TES), Thermal Emission Imaging System (THEMIS), Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité (OMEGA), Miniature Thermal Emission Spectrometer (mini-TES), and Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Because of the complicated nature of the instruments, datasets, and analysis techniques, studies have typically focused on a single wavelength region. Despite this complication , several martian compositional studies have included an analysis of both reflected and emitted light spectroscopy [1-3]. The incorporation of both visible/near-infrared (VNIR) and Thermal Infrared (TIR) datasets into surface compositional analysis can provide highly com-plimentary information based on the unique sensitivities of the two wavelength regions. In general, VNIR measurements (defined here as roughly 0.3-3μm wavelengths) are highly sensitive to mineralogies that contain transition metals and various forms of hydra-tion. In some situations, sensitivity can be extremely high (<1-2% by volume). TIR spectroscopy is generally sensitive to the bulk composition as most rock forming minerals have absorptions in this wavelength region (~5-50μm). The purpose of the work presented here is to begin to explore the combined wavelength regions in a systematic fashion in order to provide a more coherent picture of martian surface compositions. We present a number of specific surfaces that have been addressed in previous studies. Variable Lava Compositions in Nili Patera: TIR data has been used to identify compositions in Nili Pa-tera that are consistent with olivine-rich basalts and dacitic lavas [4]. Based on OMEGA data, 1 identified spectral slopes present on the high-Si unit and concluded that it was consistent with glassy coatings instead of a high-Si composition. High spatial resolution CRISM data shows that the distribution of negative spectral slopes are not correlated with the high-Si TIR unit and are most clearly present on parts of the olivine basalt unit. The presence of olivine is highly correlated between the VNIR and TIR measurements and the shallowest olivine absorptions are coincident with the TIR high-Si unit. Minor 1 and 2 μm absorp