Experimental studies of brines and evaporites as applied to Mars- Initial results from 1998-1999 runs (original) (raw)
Introduction: We are performing laboratory experiments to determine the concentrations and rates of dissolution of ions that could occur in closed, juvenile groundwater systems on Mars. Our approach is to incubate unaltered Mars-analog minerals in initially pure liquid water in contact with a Mars gas mixture for one year. At exponentially increasing time intervals, aliquots of the solutions at three different temperatures are extracted and analyzed using standard terrestrial laboratory geochemical techniques. Ultimately, our experiments will produce Mars analog brines which will be freeze dried to create evaporites. The physical and chemical properties of these evaporites will be compared with spacecraft remote sensing and in situ compositional and physical data. Evaporite deposits may represent significant sinks of mobile cations (e.g. Ca 2+ , Na + , Mg 2+ , Fe 2+) and anions (e.g. CO3 2-, NO3 2-, NO2-, SO4 2-, SO3-, Cl-) among the materials composing the martian surface and upper crust. Carbon and nitrogen are especially interesting because of their role as atmospheric gases which can become incorporated into crustal rocks. The nature of evaporite-precursor brines formed under martian conditions is poorly understood. Our laboratory studies investigating the formation of brines will greatly aid in improving our understanding of both the fluids and their precipitates (evaporites). The modeling of "warm, wet Mars" alteration and precipitate mineralogies will benefit from laboratory data of the type we discuss here.
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