Aqueous Alteration at Libya Montes Reveals Changing Geochemical Environments on Early Mars

Abstract

We analyze the emplacement chronology and aqueous alteration history of distinctive mineral assemblages and related geomorphic units near Hashir and Bradbury impact craters located within the Libya Montes. We use the morphology associated with specific mineral detections to extrapolate the possible extent of the units hosting these compositions. We characterize multiple units consistent with formation through volcanic, impact, hydrothermal, lacustrine, and evaporative processes. Altered pyroxene-bearing basement rocks are unconformably overlain by an olivine-rich unit, which is in turn covered by a pyroxene-bearing capping unit. Aqueously altered outcrops identified here include nontronite, saponite, beidellite, opal, and dolomite. See [1] for a comprehensive discussion.