EXPERIMENTAL STUDIES OF POTENTIAL CHEMICAL SIGNATURES IN SERPENTINE-WATER SYSTEMS

Serpentine, an ultramafic mineral that can form both as a direct nebular condensate and from hydrothermal aqueous alteration of Fe and Mg-bearing parent , has been observed in multiple locations in the solar system, including Earth, Mars, and Europa. Serpentine minerals are of particular interest in planetary exploration because they are habitable environments for microorganisms on Earth. Serpentinites are also rich in multiple trace elements, including Ni, Cr, Ti, Co, Cu and others. When rocks or soils, including serpentinites, interact with aqueous solutions, changes in chemistry, including trace element mobility, and mineralogy can occur. Such changes can preserve characteristics of the interactions with liquid water, including factors such as pH, duration, and chemical composition of the water, and can therefore act as signatures of those altering conditions.

We completed targeted experiments to test the hypothesis that aqueous alteration with and without organic compounds will result in chemical signatures of alteration distinct from unaltered serpentine. Such altered surfaces may therefore aid in the identification of potentially habitable serpentine environments in planetary systems. Dissolution experiments were completed using a) solutions containing inorganic acids; b) solutions containing organic compounds commonly resulting from abiotic processes (“abiotic organic compounds”); and c) solutions containing organic compounds commonly resulting from biological processes (“biotic organic compounds”). Results from these experiments will allow interpretation of potential chemical and mineralogical signatures of aqueous alteration, which are useful because they may persist in the intense radiation at the surface of some planets including Mars.