The oxygen fugacity at which graphite or diamond forms from carbonate-bearing melts in eclogitic rocks

  title={The oxygen fugacity at which graphite or diamond forms from carbonate-bearing melts in eclogitic rocks},
  author={Vincenzo Stagno and Daniel J. Frost and Catherine A. McCammon and H. Mohseni and Yi Wei Fei},
  journal={Contributions to Mineralogy and Petrology},
The oxygen fugacity (fO2) at which carbonate-bearing melts are reduced to either graphite or diamond in synthetic eclogite compositions has been measured in multi-anvil experiments performed at pressures between 3 and 7 GPa and temperatures between 800 and 1,300 °C using iron–iridium and iron–platinum alloys as sliding redox sensors. The determined oxygen fugacities buffered by the coexistence of elemental carbon and carbonate-bearing melt are approximately 1 log unit below thermodynamic… 
The fate of carbonate in oceanic crust subducted into earth's lower mantle
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The oxidation state of deeply subducted, altered oceanic crust: an experimental study and the evidence from natural samples
Eclogitic xenoliths from kimberlites are occasionally diamond-bearing, and are often interpreted as having an origin as subducted oceanic crust. The existence of diamonds in these rocks constrains
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Ab initio molecular dynamics calculations on a carbonate‐silicate‐metal melt were performed to study speciation and coordination changes as a function of pressure and temperature. We examine in
Carbon, carbides, carbonates and carbonatitic melts in the Earth's interior
  • V. Stagno
  • Geology
    Journal of the Geological Society
  • 2019
Over recent decades, many experimental studies have focused on the effect of CO2 on phase equilibria and melting behaviour of synthetic eclogites and peridotites as a function of pressure and
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The formation of diamonds within eclogitic rocks has been widely linked to the fate of carbon during subduction and, therefore, referred to conditions of pressure, temperature, and oxygen fugacity
Experimental quantification of vanadium partitioning between eclogitic minerals (garnet, clinopyroxene, rutile) and silicate melt as a function of temperature and oxygen fugacity
Vanadium is a multivalent element that may speciate as V2+; V3+; V4+ and V5+ in silicate and oxide phases. The relative abundance of V in planetary materials can be used as a proxy for oxygen


The stability of magnesite in the transition zone and the lower mantle as function of oxygen fugacity
The oxygen fugacity at which magnesite (MgCO3) is reduced to diamond in a typical mantle assemblage has been determined between 16 and 45 GPa and 1500–1700°C in experiments employing a multianvil
Role of iron and reducing conditions on the stability of dolomite + coesite between 4.25 and 6 GPa – a potential mechanism for diamond formation during subduction
We have investigated the effect of iron and oxygen fugacity on dolomite + coesite stability during subduction. For redox conditions buffered by the assemblage itself, the presence of iron (Fe/(Fe +
Phase relations of carbonate-bearing eclogite assemblages from 2.5 to 5.5 GPa: implications for petrogenesis of carbonatites
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An experimental study of the Fe oxidation states in garnet and clinopyroxene as a function of temperature in the system CaO–FeO–Fe2O3–MgO–Al2O3–SiO2: implications for garnet–clinopyroxene geothermometry
Samples with eclogitic composition in the system CaO–FeO–Fe2O3–MgO–Al2O3–SiO2 were produced from various kinds of starting materials held in graphite-lined Pt capsules at a pressure of 2.5–3.0 GPa
An Experimental Study of Carbonated Eclogite at 3·5–5·5 GPa—Implications for Silicate and Carbonate Metasomatism in the Cratonic Mantle
We have experimentally investigated a K-bearing altered mid-ocean ridge basalt (MORB) composition to which 10% CaCO3 was added (GA1+10%cc), at temperatures of 1050-1400oC and pressures of 3•5-5•5