Evidence for magma‐carbonate interaction beneath Syrtis Major, Mars

Abstract

We used three methods—spectral index mapping, linear spectral mixture analysis, and factor analysis and target transformation—to determine if carbonate decomposition products, including lime (CaO), periclase (MgO), portlandite (Ca(OH)2), and brucite (Mg(OH)2), are present on the surface of Mars. Using an expanded spectral library that includes decomposition products of calcite and magnesite, we deconvolved a binned emissivity data set from the Mars Global Surveyor Thermal Emission Spectrometer (MGS‐TES). The deconvolution model indicates that anhydrous carbonates are not present at kilometer scales above the TES detection limit; however, carbonate decomposition products may be present at or above the TES detection limit in northeast Syrtis Major and several other small regions on Mars. The model results are supported by spectral index mapping and factor analysis and target transformation of TES data in this region. The volcanic setting of the detections may indicate the interaction of Syrtis Major lavas with subsurface carbonates, or, alternatively, the eruption of carbonate‐bearing lavas that were subsequently devolatilized by impacts or later lava flows.