Early diagenesis at and below Vera Rubin ridge, Gale crater, Mars

Data returned by NASA’s Mars Science Laboratory Curiosity rover showed evidence for abundant secondary materials, including Fe-oxides, phyllosilicates, and an amorphous component on below Vera Rubin ridge in the Murray formation. We used equilibrium thermochemical modeling to test hypothesis that altered sediments were deposited as detrital igneous grains subsequently underwent diagenesis. Chemical compositions of formations’ components calculated using data chemistry mineralogy X-ray diffraction instrument alpha particle spectrometer board Curiosity. Reaction these alteration with a CO2-poor oxidizing dilute aqueous solution was modeled at 25–100 °C, 10–50% Fe3+/Fetot host rock. The assemblages included phyllosilicates Fe-oxides water-to-rock ratios >100. Modeled abundances directly comparable observed hematite clay minerals ratio 10,000, system temperatures 50–100 °C fluid pH ranging from 7.9 9.3. Modeling results suggest hematite–clay mineral assemblage is primarily result enhanced groundwater flow compared Sheepbed mudstone Yellowknife Bay, further, localized produce