Isotope ratios in nature can change during equilibrium or kinetic processes because different isotopes of the same element have slightly different physical and chemical properties. Isotope fractionation during diffusion is a fundamental process with multiple applications, including development of methods for separation of isotopes, correction for isotope ratios in isotope age determination, examination of atomic scale processes of diffusion, and inference of history and rate of rock formation. This project will investigate isotope fractionation during multicomponent diffusion in molten basalts with natural isotope compositions. Specifically, diffusive isotope fractionation of three major elements in rocks, K, Ti, and Mg, will be evaluated. The project will provide a research opportunity for a graduate student. New methodologies and analytical protocols will be developed that will be useful to many other researchers.
Isotope ratios of K, Ti ad Mg in existing well-characterized experimental charges will be measured by pushing the limits of current SIMS instruments to resolve the isotope ratio variation in the quenched glass. The isotope data to be acquired will ultimately enable researchers to understand diffusion mechanisms at the fundamental molecular and ionic level. The project will also advance the SIMS technique for isotope ratio measurements and will have applications to isotope fractionation during natural processes of magma mixing as well as mineral dissolution and growth. This work will contribute to the fundamental understanding of diffusion and isotope fractionation in mafic silicate melts. In addition, the results can be applied to understand magma mixing and mineral growth, and to infer cooling time scales of rocks. Graduate students will be trained and will attend scientific meetings.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
