This study will calibrate a thermodynamic model for sulfur in silicate melts as a function of temperature, pressure, oxygen fugacity, sulfur fugacity and bulk melt composition. The resulting model will be applicable to a wide range of problems in igneous petrology, volcanology, magmatic ore genesis, planetary geology, and metallurgy. Two categories of experiments will be performed. The first set will study a variety of silicate melt compositions in a controlled sulfur atmosphere at super-liquidus temperatures to calibrate a thermodynamic model for sulfur. Results will be used to incorporate sulfur into Ghiorso and Sack's (1995) MELTS model. A second set of experiments will determine the partial molar volumes of sulfide liquid components in the system O-S-Fe-Ni-Cu. These experiments will employ a modified single-bob Archimedian method to measure density. Results will be used to calibrate a model for sulfur in silicate liquids at pressure.
