Experimental study of sulfur solubility in silico-carbonatitic melts at pressures of 6-10 GPa

• Applicant: Professor Dr. Alan Butler Woodland
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: from 2017 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 378270953

Although sulfur is a minor constituent of the Earths mantle, the presence or absence of sulfide minerals mainly determines the trace element signature and behavior of the chalcophile elements (e.g. Pb, Re and platinum group elements). In addition, the common occurrence of sulfides as inclusions in diamond suggests they may be intimately related to the process of diamond formation and growth. A number of experimental studies have determined the S-solubility of silicate melts as a function of pressure, temperature and oxygen fugacity. However, only very limited information is available on the S solubility of carbonatitic and silico-carbonatitic melts. This is in spite of the fact that such melts may be important agents for metasomatism in the upper mantle and that their S concentrations may exceed those of silicate melts at similar conditions. In this project, we aim to determine the sulfur concentration in sulfide-saturated carbonatitic and silico-carbonatitic melts at pressures of 6-10 GPa, temperatures of 1200-1500°C and at relatively oxidizing and reducing conditions. To do this we will develop an experimental approach that physically separates the sulfide from the carbonate-bearing melts in order to avoid contamination by S droplets during chemical analysis. Test experiments using olivine capsules provide a promising starting point for this project. These results have application to understanding the role of S during silico-carbonatitic melt metasomatism in the upper mantle and the behavior of chalcophile elements during such a process.

• DFG Programme: Research Grants
• Co-Investigator: Professor Gerhard Peter Brey, Ph.D.