9527567 Crowe This project is to evaluate the efficacy of the ion microprobe to precisely and accurately determine 18O/18O ratios in non-conducting silicate phases, in particular garnet. Used primarily for heavy isotope measurement, ion probes have recently been used to measure light stable isotope ratios, although precision limits have typically been poor due to counting statistics and a lack of properly characterized standards to correct for solid solution-dependent matrix effects. The PI's have developed a set of isotopically homogeneous, well characterized grossular and andradite ion probe standards that significantly improve both the precision and accuracy of results. New, high precision ion probe data generated by the PI's demonstrate the potential of the technique, and funding is to continue and further this work.
