HYDRATED AND MAFIC MINERALOGY OF GANGES CHASMA, MARS

The chasmata of Valles Marineris have a complex history, opening in the Late Noachian to Early Hesperian as Tharsis shield emplacement began stressing the adjoining crust. Before, during, and after opening, magmatic activity continued within the chasmata, emplacing olivine-rich dikes and caldera/vent structures. Throughout the Hesperian, the sulfate-bearing Interior Layered Deposits (ILDs) were emplaced in many chasmata. Because ILD emplacement was occurring around the same time as the region’s magmatic activity, several questions remain as to the relationship between ILDs and magmatic features. Ganges Chasma, in northeast Valles Marineris, is an ideal area to investigate the relationship between sulfate-bearing ILDs and magmatic features, because the chasma has both a typical ILD and one of the strongest olivine signatures in the region. Here, we present an updated mineralogical map of Ganges Chasma, synthesizing analysis of new CRISM data with previous data sets from multiple instruments. We report new outcrops of bedrock olivine, an outcrop of serpentine on the surrounding plateau, and a revised map of the mineralogy of the sulfate-bearing ILD. Particular attention is paid to relationships between the sulfate-bearing ILD and newly mapped olivine-bearing dikes on the chasma floor.