Kinetic Fractionation of Stable Isotopes in Carbonates on Mars: Terrestrial AnalogsAn ancient Martian hydrosphere consisting of an alkali-rich ocean would likely produce solid carbonate minerals through the processes of evaporation and/or freezing. We postulate that both (or either) of these kinetically-driven processes would produce carbonate minerals whose stable isotopic compositions are highly fractionated (enriched) with respect to the source carbon. Various scenarios have been proposed for carbonate formation on Mars, including high temperature formation, hydrothermal alteration, precipitation from evaporating brines, and cryogenic formation. 13C and 18O -fractionated carbonates have previously been shown to form kinetically under some of these conditions, ie.: 1) alteration by hydrothermal processes, 2) low temperature precipitation (sedimentary) from evaporating bicarbonate (brine) solutions, and 3) precipitation during the process of cryogenic freezing of bicarbonate-rich fluids. Here we examine several terrestrial field settings within the context of kinetically controlled carbonate precipitation where stable isotope enrichments have been observed.
Document ID
20030110776
Acquisition Source
Headquarters
Document Type
Conference Paper
Authors
Socki, Richard A. (Lockheed Martin Corp. Houston, TX, United States)
Gibson, Everett K., Jr. (NASA Johnson Space Center Houston, TX, United States)
Golden, D. C. (Hernandez Engineering, Inc. Houston, TX, United States)
Ming, Douglas W. (NASA Johnson Space Center Houston, TX, United States)
McKay, Gordon A. (NASA Johnson Space Center Houston, TX, United States)