Results 131 to 140 of about 1,482 (183)
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Plate subduction, oxygen fugacity, and mineralization
Journal of Oceanology and Limnology, 2019Plate subduction is the largest natural factory that processes elements, which controls recycling and mineralization of a variety of elements. There are three major ore deposit belts in the world: the circum-Pacific, the central Asian, and the Tethys belts. All the three belts are closely associated with plate subductions, the mechanism remains obscure.
He Liu +4 more
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Equilibrium Oxygen Fugacity in Titanium Ferrites
Zeitschrift für anorganische und allgemeine Chemie, 1986AbstractThe subsolidus equilibrium oxygen fugacities for the boundaries of the Fe3O4Fe2TiO4 stability field above 1000°C have been calculated from available data. A Frenkel point defect equilibrium model is described, which uniquely determines the single phase intrinsic oxygen fugacity, as a function of temperature, Ti content, and metal‐oxygen ...
J. M. Honig, R. Aragón
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The magmatic oxygen fugacity of an ultrabasic dyke
Contributions to Mineralogy and Petrology, 1971The magmatic oxygen fugacity (fO2) of a thirty foot wide feldspathic peridotite dyke has been determined using the experimental method of Fudali (1965). Determinations were made on samples from both the marginal and central portions of the dyke and a difference of approximately one order of magnitude in fO2 was observed.
Henderson, C. M. B., Gibb, F. G. F.
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Oxygen diffusion in olivine: Effect of oxygen fugacity and implications for creep
Journal of Geophysical Research: Solid Earth, 1989Oxygen self‐diffusion experiments on single crystals of San Carlos olivine (∼Fo92) at 1200° ≤ T ≤ 1400°C, oxygen fugacities (ƒO2) along the Ni‐NiO and Fe‐FeO buffers, and silica activity at the olivine‐orthopyroxene buffer yielded results that follow the relationshipD= 2.6 × 10−10ƒO20.21±0.03exp [−266±11 (kJ mol−1/RT)], whereDis the diffusion ...
F. J. Ryerson +3 more
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The color of meteoritic hibonite: an indicator of oxygen fugacity
Earth and Planetary Science Letters, 1986Hibonites similar in composition to those found in Ca-Al-rich inclusions change color from blue, to green, to orange, to nearly colorless as oxygen fugacity is increased at high temperature from below the iron-wustite buffer up to air. The development of the blue color is correlated with the growth of an absorption band at 715 nm in the optical spectra
Ihinger, Phillip D., Stolper, Edward
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Oxygen fugacity of the diamond + CO fluid assemblage and CO2 fugacity at 8 GPa
Earth and Planetary Science Letters, 1994Abstract We have bracketed the oxygen fugacity ( ƒ O 2 ) of the diamond + CO fluid buffer (CCO) relative to the wustite-magnetite (WM) and nickel-nickel oxide (NNO) buffers at 8 GPa and 950–1550°C using a Walker-style multi-anvil press. The intersection of CCO with WM is between 1050° and 1150°C and thus the log ƒ O 2 of CCO at
Tom LaTourrette, John R. Holloway
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Oxygen fugacities of basaltic and andesitic magmas
Geochimica et Cosmochimica Acta, 1965Experimentally determined oxygen fugacities in equilibrium with the original ferrous to ferric iron ratios of nine basalts and andesites range from 10−8·5 to 10−6·4 atm at 1200°C. There is a strong tendency for the ƒO2 to increase with increasing acidity of the rocks studied.
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Intrinsic oxygen fugacities of diogenites and mesosiderite clasts
Geochimica et Cosmochimica Acta, 1984Oxygen fugacities of diogenite and mesosiderite clast material were measured with the double ZrO2 cell technique between 800 and 1150 C. The samples were taken from large clasts in the diogenites Johnstown (En73) and Tatahouine (En75), and the mesosiderites Estherville (En81), West Point (Fo88) and Emery (En68).
Roger H. Hewins, G.C. Ulmer
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Oxygen fugacity constraints on the southern African lithosphere
Contributions to Mineralogy and Petrology, 1991Oxygen fugacities are calculated for olivine—spinel ±orthopyroxene assemblages recovered from diamonds and the concentrate of the Dokolwayo kimberlite, Swaziland. In addition thermobarometric oxygen fugacities are obtained for chrome spinel-garnet peridotites and diamonds from several other southern African kimberlites. The southern African lithosphere
Gurney, J. J., Daniels, L. R. M.
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Armalcolite stability as a function of pressure and oxygen fugacity
Geochimica et Cosmochimica Acta, 1977High-pressure experiments in a piston-cylinder apparatus with silver-palladium containers were conducted to study the stability of synthetic armalcolite, (Fe,Mg)Ti2O5, as a function of pressures up to 15 kbar at 1000, 1100, and 1200 C. Three armalcolite compositions were used, each with an initial Fe/(Fe + Mg) ratio of 0.5.
John J Friel, R.Ian Harker, Gene C Ulmer
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