Evidence for extensive, olivine-rich bedrock on Mars

Color infrared observations of an area around the Nili Fossae acquired by the Mars Odyssey thermal emission imaging system have been used to map the regional distribution and geologic context of olivine-rich materials that first were identified from Mars Global Surveyor thermal emission spectrometer data. Spectral, thermal, geomorphic, and topographic data demonstrate that the majority of olivine-rich material is in the form of inplace layered rock covering an area roughly four times larger than previously recognized. Some high olivine concentrations are associated with spatially small areas dominated by sediments. We favor olivine-rich basalts as the origin of the observed olivine enrichment, although several hypotheses are viable.