Supercritical water and carbon dioxide, the two principal volatiles in Earth's mantle, affect most geochemical and geophysical processes. Despite the importance of these fluids, few experimental data exist concerning their properties in high-pressure, high-temperature environments. The purpose of this research is to gather precise and accurate thermodynamic data on these two fluids at pressures up to at least 10 GPa and temperatures of at least 900K. The results will improve our understanding of a variety of mantle processes, including the geochemical segregation of minerals, the formation of hotspot and other volcanoes, and the Earth's carbon budget.
