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Showing 1 to 20 of 42 for “"oxygen fugacity"”.
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The crystal chemistry of hibonite: an indicator for oxygen fugacity during Solar nebula condensation?
… the years as it could be used to constrain the oxygen fugacity, fO2, at the time of Solar Nebula condensation. CAIs contain minerals which appear earlier in the condensation sequence of a hot gas having Solar composition. Among these minerals, Ti-rich clinopyroxenes, Ca(Mg,Al,Ti)(Si,Al)2O6, and …
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The carbon speciation in the Earth’s interior as function of pressure, temperature and oxygen fugacity
… in the mantle can be strongly effected by the oxygen fugacity because reduced phases such as diamond and graphite are immobile and likely to remain within the mantle and potentially within subducting slabs, while at more oxidizing conditions CO2-rich fluids or melts can migrate and escape from …
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The dependence on oxygen fugacity of nickel and cobalt partitioning between olivine and silicate melt
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1991.
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The Influence of Variable Oxygen Fugacity on the Source Depths for Lunar High-Titanium Ultramafic Glasses
… experiments were carried out under variable oxygen fugacity conditions on lunar high titanium ultramafic glasses to determine the conditions of multiple saturation where both olivine and orthopyroxene are stable on the liquidus. The investigated compositions are the Apollo 17 Orange glass …
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Iron-magnesium amphiboles: synthesis and stability with respect to temperature, pressure, oxygen fugacity, and sulfur frugacity
… data does not allow a rigorous analysis. Sulfur fugacity for runs was determined from pyrrhotite compositions while f<sub>O₂</sub> was known from an experimentally determined magnetite-pyrrhotite curve. Knowledge of these two fugacities allowed calculation of fugacities of all species, including …
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Calculation of temperature - oxygen fugacity tables for H₂-CO₂ gas mixtures at one atmosphere total pressure, and an investigation of the zoisite-clinozoisite transition
Part I: Calculation of Temperature - Oxygen Fugacity Tables for H₂ - CO₂ Gas Mixtures at One Atmosphere Total Pressure. The initial CO₂ volumes yielding selected oxygen fugacities at specified temperatures have been computed for H₂ - CO₂ gas mixtures at one atmosphere total pressure. The …
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Carbon in Silicate Melt - Experimental Constraints and Applications for the Subduction Zone and Magma Ocean Carbon Cycles
… the pressure, temperature, H2O content, and oxygen fugacity dependence of CO2 solubility on natural hydrous rhyolitic melts. These studies are applicable to subduction zone settings of the Earth throughout its history. Carbon concentrations and speciation were measured using FTIR, and in the …
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The role of C-O-H volatiles in the martian mantle and the production of the martian atmosphere.
… a simple relationship between CO2 solubility and oxygen fugacity (fO2) which shows that an order of magnitude increase in oxygen fugacity changes the amount of CO2 dissolved in the melt by one order of magnitude. This thesis presents experimental investigations of the solubility of CO2, and other …
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Petrologic and Thermodynamic Investigation of the Aqueous Transport of Platinum-Group Elements During Alteration of Mafic Instrusive Rocks
… spinels and ilmenite delineate a temperature-oxygen fugacity trajectory for fluid-rock reaction that extends from ~750ºC and 2 units below the value of the fayalite-magnetite-quartz buffer assemblage (i.e., FMQ-2) to ~350ºC and FMQ-9. This trend is more reduced than that for a PGE-rich oxide …
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Petrology and Geochemical Evolution of the East Hill Suite of the Mont Saint-Hilaire Alkaline Plutonic Complex
… Mineral geochemistry indicates decreasing oxygen fugacity with cooling, and phases such as titanite (present) and aenigmatite (absent) defined boundaries in fO2 – T space. Oxygen fugacity data combined with petrography and geothermometry defined an 2 fO – T curve for the East Hill suite …
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Experimental studies of melting and crystallization processes in planetary interiors
… were designed to explore the e ects of variable oxygen fugacity (fO2) on the high pressure and high temperature crystallization of olivine and orthopyroxene in high-Ti magmas. The results of these experiments showed that the source regions for the high-Ti lunar magmas are distributed both …
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Experimental studies of melting and crystallization processes in planetary interiors
… were designed to explore the effects of variable oxygen fugacity (fo₂) on the high pressure and high temperature crystallization of olivine and orthopyroxene in high-Ti magmas. The results of these experiments showed that the source regions for the high-Ti lunar magmas are distributed both …
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Mantle and crustal controls on the distribution of chalcophile elements in silicate melts
… of melt composition, temperature, pressure and oxygen fugacity. Given that these variables can vary substantially across different tectonic settings, the mechanisms which control the abundance and distribution of CSE in different magmatic environments are poorly constrained. In this thesis, I …
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Magmatic processes that generated the rim andesites of Medicine Lake Volcano, N. California
… H20 over a temperature range of 1070 to 900 C. Oxygen fugacity recorded in coexisting spinel and rhombohedral oxides varies from NNO (Nickel - Nickel Oxide) to NNO 0.7 log units. Experiments performed at 1 kbar - H20 saturated conditions at the NNO buffer on a primitive andesite reproduce most …
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Partial Melting on FeO-Rich Asteroids: Insights to the First Stage of Planetary Differentiation
… primitive achondrites. Mineral compositions and oxygen fugacity formation conditions indicate that the brachinites could have formed from a parent body much like the R chondrites. Gas-mixing, partial melting experiments of a R4 chondrite LaPaz Ice Field 03639 at 1250 °C and an oxygen fugacity of …
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Primitive magmas of the Earth and Moon : a petrologic investigation of magma genesis and evolution
… model the dependence of alloy composition on the oxygen fugacity. Au-Pd alloy capsules are essential to hydrous phase equilibrium studies at high-pressure and high-temperature, and the use of this model allows for the quantification of the oxygen fugacity of these experiments without compromising …
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Iron oxidation in (Mg,Fe)0: Calibration of the Flank method on synthetic samples and applications on natural inclusions from lower mantle diamonds
… Fe3+ concentration in (Mg,Fe)O is sensitive to oxygen fugacity, even at high pressures. Therefore, the determination of Fe3+/Fetot in such inclusions provides a direct method for investigating lower mantle redox conditions during diamond formation. The goal of the present research is to …
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Compositional Analysis of the Martian Meteorites Northwest Africa 6342 and Northwest Africa 10961
… material) crystallization. Calculated oxygen fugacity values for NWA 6342 are more reduced (FMQ -3.0) within the poikilitic regions and more oxidized (FMQ -2.2) within the interstitial areas, likely representing auto-oxidation and degassing during crystallization. Calculated average …
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Geochemical fractionation during melting of sulfide and sulfate bearing mantle lithologies
… S contribution from the subducting slab and the oxygen fugacity of the subducting crust, partitioning experiments of trace elements between anhydrite (sulfate mineral) and hydrous slab melt were performed (Chapter 3). As Light Rare Earth Elements (LREEs) partitions into sulfate phase and …
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Mantle conditions and kimberlite geochemical criteria controlling diamond survival in Kimberlites
… are formed at high pressure, temperature and low oxygen fugacity conditions in the Earth's deep mantle. However, during their residence in the mantle and transport to the surface by kimberlite magma, they may be exposed to deformation or oxidising conditions outside of their stability field, …
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