Using THEMIS data to resolve the discrepancy between CRISM/OMEGA and TES modeled phyllosilicate abundance in Mawrth Vallis

Abstract

We explore the effects of spatial resolution on the detectability of phyllosilicates in the thermal infrared dataset from the Mars Global Surveyor Thermal Emission Spectrometer (TES). Data from the Mars Odyssey THermal Emission Imaging System (THEMIS) instrument is used to resolve spatial resolution driven discrepancies between detection of phyllosilicates in the infrared and visible/near-infrared wavelength range. The 100-m/pixel spatial resolution offered by THEMIS, even with its limited spectral resolution, significantly improves the likelihood of phyllosilicate detection. Furthermore, spectral unit mapping techniques provide the first phyllosilicate abundance maps of the Mawrth Vallis phyllosilicate-bearing units, which indicate phyllosilicate abundances of >50% with heterogeneous spatial distributions. Derived abundances are used to evaluate the proposed formation mechanisms for phyllosilicates in this region and are found to be consistent with intermediate weathering of mafic primary material.