This work will consist of experiments on melting in silicate- carbonate-CO2-H2O systems with applications to the origin of kimberlites and carbonatites, which relate directly to mantle processes. The project is to trace the reduced volatile components and their metasomatic and magmatic effects from deep mantle through oxidation to their consolidation in or evolution from near-surface magmas. Comprehensive petrogenetic schemes developed recently for the origin of kimerlites, nephelinites and carbonatites will be tested in experiments using natural minerals recombined in proportions suitable for rock reaction studies.