CHEMICAL SIGNATURES OF OF BIOLOGICAL IMPACTS ON SERPENTINITE WEATHERING

Serpentine, 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, as well as because they are rich in multiple trace elements, including Ni, Cr, Ti, Co, and Cu. When rocks or soils interact with aqueous solutions, changes in chemistry 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 whole rock serpentinite dissolution experiements to test the hypothesis that aqueous alteration with and without organic compounds will result in chemical signatures of alteration distinct from unaltered serpentine. Dissolution experiments were completed using solutions containing a) inorganic acids; b) organic compounds commonly resulting from abiotic processes (“abiotic organic compounds”); and c) organic compounds commonly resulting from biological processes (“biotic organic compounds”). Results from these experiments show that biotic organic compands cause serpentinite to dissolve significantly faster than serpentinite dissolution in the presence of either group of abioitc compounds. These results will allow interpretation of potential chemical and mineralogical signatures of aqueous alteration in the presence of organic acids that are derived from biota, which are useful because they may persist in the intense radiation at the surface of some planets including Mars.