Geoclub Seminar Series

We present isotopic measurements of mineral-bound water from rocks sampled by the Curiosity rover. These hydrous minerals' strong 18O enrichments are the first discovery of such in an ancient martian water reservoir. Extreme deuterium enrichments record atmospheric hydrogen loss and reveal chemical weathering in early martian near-surface environments. The amplitude of 18O enrichment and its correlation with deuterium in related samples indicate formation in an ancient lacustrine setting that underwent extensive evaporation into a low-humidity atmosphere—a novel insight into the early martian hydrologic cycle that contextualizes previous sedimentological, mineralogical, and stratigraphic evidence. These data provide the clearest view to-date of a martian lake's hydrology during a period when climate change, chemical weathering, and prebiotic chemistry were active on Mars.