This proposal will continue several lines of research in which the laboratory is currently active, as follows: (1) Oxygen and silicon isotopes in primitive and differentiated meteorites to study nebular and planetary processes. (2) Experimental determination of oxygen isotope equilibrium constants using novel silicate-carbonate exchange techniques. (3) Systematic re-evaluation of oxygen isotope thermometry of igneous and metamorphic rocks, using new fractionation factors. (4) Laboratory studies of anomalous isotope exchange in the reaction of O3, using a wide range of isotopic compositions of oxygen. (5) Theoretical and experimental study of oxygen in the Earth's upper atmosphere. (6) Oxygen isotope studies of granulites and eclogites. Results over the past three years have been gratifying. It is planned to continue work on some of the most rewarding of these, as well as open some new lines of research, such as (4) above.
