FORMATION OF OLIVINE-ENRICHED NOACHIAN INTERCRATER PLAINS MATERIALS: INSIGHTS FROM SURFACE MORPHOLOGY

We present results from a global spectral and morphological survey of thermally distinct intercrater plains surfaces in the Noachian cratered highlands of Mars. Using THEMIS thermal infrared spectra, we find that these surfaces are largely composed of olivine-enriched materials relative to their surroundings. Spectral modeling of these surfaces by the addition of olivine to the surrounding materials suggests intercrater plains are generally enriched in olivine by less than 10%. Morphological observations of these surfaces using ~6 m/px CTX imagery finds that these olivine-enriched units most commonly correspond to friable or sand-rich surface lithologies, finely-layered bedrock units, and/or units with apparent inverted topography. These observations suggest that olivine enrichments in many Martian intercrater plains likely arise from density sorting of olivine during surface transport or modification, and not volcanic processes.