Formation of Tridymite and Evidence for a Hydrothermal History at Gale Crater, Mars

In August 2015, the Curiosity Mars rover discovered tridymite, a high-temperature silica polymorph, in Gale crater. The existing model for its occurrence suggests erosion and detrital sedimentation from silicic volcanic rocks crater rim or central peak. chemistry mineralogy of tridymite-bearing rocks, however, are not consistent with material. Using data Curiosity, including chemical composition Alpha Particle X-ray Spectrometer, CheMin instrument, evolved gas isotopic analyses Sample Analysis at we show that exhibit similar patterns silica-rich alteration halos which crosscut stratigraphy. We infer tridymite formed in-place through hydrothermal processes additional mineralogical results activity occurring after sediment deposition lithification.