Etienne Medard
Massachusetts Institute of Technology
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Featured researches published by Etienne Medard.
American Mineralogist | 2008
Etienne Medard; Catherine McCammon; J. A. Barr; Timothy L. Grove
Abstract The Pt-graphite double-capsule technique is a very commonly used method in high-temperature, high-pressure experimental petrology, particularly for anhydrous experiments relevant to primitive basaltic magmas and mantle melting. We have performed a series of experiments that place better constraints on the range of oxygen fugacity imposed by this capsule material, on the Fe3+/Fe2+ ratios in experimentally produced melts and minerals, and on the temperature reproducibility in Pt-graphite capsules. Oxygen fugacity in our piston-cylinder experiments using Pt-graphite capsules is CCO-0.7 (IW+1.5, QFM-2.2) at 1.5 GPa and 1360 °C. Comparison with other estimates and thermodynamic calculations indicate that a value of CCO-0.8 ± 0.3 can be used as a first approximation at least over the P-T range relevant for MORB and OIB magma generation (0.5-3.0 GPa, 1100-1500 °C). Under those conditions, the amount of Fe3+ in silicate phases (pyroxenes, olivine, glass) and spinel is negligible (Fe3+/ ΣFe < 0.05) and would not significantly affect thermodynamic properties. Significantly higher values of fO₂ cannot be achieved using Pt-graphite or graphite only capsules, but fO₂ can be tuned to lower values by using small pieces of PtFe alloys. The potential range of fO₂ that can be reached in graphite or Pt-graphite capsules is CCO to CCO-4. Temperature reproducibility in piston-cylinder experiments has been examined and can be as low as ±10 °C. Finally, unless capsules are dried overnight at 400 °C before the experiment, small amounts of H2O are always present in nominally dry experiments. These small amounts of H2O should not, however, significantly change phase relations.
Earth and Planetary Science Letters | 2006
Timothy L. Grove; Nilanjan Chatterjee; Stephen W. Parman; Etienne Medard
Contributions to Mineralogy and Petrology | 2008
Etienne Medard; Timothy L. Grove
Meteoritics & Planetary Science | 2007
Anna G. Monders; Etienne Medard; Timothy L. Grove
Archive | 2006
Timothy L. Grove; Nilanjan Chatterjee; Stephen W. Parman; Etienne Medard
Journal of Geophysical Research | 2006
Etienne Medard; Timothy L. Grove
Geochemistry Geophysics Geosystems | 2008
Marc M. Hirschmann; Mark S. Ghiorso; Fred A. Davis; S. M. Gordon; S. Mukherjee; Timothy L. Grove; M. Krawczynski; Etienne Medard; Christy B. Till
Archive | 2007
C. B. Till; Timothy L. Grove; Anthony C. Withers; Marc M. Hirschmann; Etienne Medard; Natasha Chatterjee
Archive | 2007
Timothy L. Grove; M. J. Krawczynski; Etienne Medard
Archive | 2007
Etienne Medard; Timothy L. Grove