AN EXPERIMENTAL PERSPECTIVE ON NON-TRADITIONAL STABLE ISOTOPE GEOCHEMISTRY (Invited Presentation)

Since the advent of the multiple collector inductively coupled mass spectrometer (MC-ICPMS), natural variations of stable isotope ratios have been found for almost any element measured. Although it has been known that as temperature and mass increase, isotope fractionation decreases very quickly, the MC-ICPMS has revolutionized the ability of a geochemist to measure very small differences in isotope ratios. This presentation is devoted to explaining the techniques involved with laboratory experiments of non-traditional isotope fractionation factors as well as the best practices that have been learned. Although experimental petrology has been around for a long time and basic experimental methods have been well-refined, there are additional considerations that must be taken into account when the goal is to measure isotopic compositions at the end of the experiment. It has been only about ten years since these initial studies were published but much has been learned in that time about how best to conduct experiments aimed at determining equilibrium fractionation factors. We will discuss what we have learned about conducting high temperature and pressure experiments for the use of obtaining equilibrium fractionation factors and then give some examples of recent work that uses those principles. While many of the experiments we have conducted are aimed at understanding very high temperature planetary scale processes, the same techniques can be used to understand isotope fractionation in any Earth system of interest.