Martian Cryogenic Carbonate Formation: Stable Isotope Variations Observed in Laboratory Studies

Summary and implications for Mars: The results of this study reveal that there are large variations in the isotopic enrichments of each experiment, even though these experiments were conducted under similar conditions. This degree of isotopic variability has also been observed in natural samples associated with ter-restrial cryogenic environments [14] and could be a characteristic feature of carbonates precipitated under kinetic conditions. This observed variability likely re-sults from the nature of carbonate precipitation in cryo-genic or arid environments where there are multiple smaller episodes of carbonate precipitation driven by short duration wetting and/or melting events. These short duration kinetic effects result in isotope fraction-ations that may be similar to those observed in the ex-perimental work described here, thereby producing variable isotopic composition of precipitated carbon-ates. Furthermore, large isotope variability has also in the carbonates from martian meteor-ites [15]. The isotope variabilityseen in martian car-bonates could also be the resultof precipitation con-trolled by kinetics associated with cryogenic carbonate ecipitation, similar to the cryogenic processes studied in the experiments reported here. In addition to crygenically driven precipitation, kinetic processes affect-ing isotope composition could also accompany carbon-ate precipitation driven by rapid boiling and evapora-.