The graphite-COH fluid equilibrium in P,T, f_{O_2 } space |
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| Authors: | Peter Ulmer Robert W. Luth |
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| Affiliation: | 1. ETH-Zentrum, Institut für Mineralogie und Petrographie der ETHZ, CH-8092, Zürich, Switzerland
2. C.M. Scarfe Laboratory of Experimental Petrology, Department of Geology, University of Alberta, T6G 2E3, Edmonton, Alberta, Canada
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| Abstract: | The oxygen fugacity (  ) of a C-O-H fluid in equilibrium with graphite has been determined in the range 10–30 kbar by equilibrating solid  -buffer assemblages in graphite capsules containing C-O-H fluid. By using different buffers (FexO-Fe3O4, Ni-NiO, Co-CoO, Mo-MoO2), the  of the graphite-saturated fluid is bracketed within a narrow range. This technique produces a calibration for the  imposed on a sample contained within a graphite capsule. To achieve a thermodynamically-invariant system at fixed P and T, the  was imposed on the system with an external buffer and the double-capsule technique. The experiments were performed in solid-media, high pressure apparatus with 19 mm tale-pyrex assemblies. A series of experiments at 10, 15, 20, 25, and 30 kbar, 800–1600° C, with  imposed by the Fe2O3-Fe3O4-H2O equilibrium were conducted. The experimental results have been fitted to the following equation:
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