Results 131 to 140 of about 1,474 (181)

The magmatic oxygen fugacity of an ultrabasic dyke

Contributions to Mineralogy and Petrology, 1971
The 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, 1989
Oxygen 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, W. B. Durham, D. J. Cherniak, W. A. Lanford   +3 more
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The color of meteoritic hibonite: an indicator of oxygen fugacity

Earth and Planetary Science Letters, 1986
Hibonites 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 + CO fluid assemblage and CO2 fugacity at 8 GPa

Earth and Planetary Science Letters, 1994
Abstract We have bracketed the oxygen fugacity ( ƒ O 2 ) of the diamond + CO 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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Intrinsic oxygen fugacities of diogenites and mesosiderite clasts

Geochimica et Cosmochimica Acta, 1984
Oxygen 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, 1991
Oxygen 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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Oxygen fugacities of basaltic and andesitic magmas

Geochimica et Cosmochimica Acta, 1965
Experimentally 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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Armalcolite stability as a function of pressure and oxygen fugacity

Geochimica et Cosmochimica Acta, 1977
High-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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Sodic Amphiboles as Oxygen Fugacity Indicators in Metamorphism

The Journal of Geology, 1980
Analyses of sodic amphiboles from a blueschist metamorphic terrain of constant grade in the Tavsanli area, Northwest Turkey, show that practically the whole range of sodic amphibole compositions is stable in the glaucophane-lawsonite facies. By analysing sodic amphiboles coexisting with magnetite and hematite, it has proved possible to plot for a ...
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Zircon as a recorder of the oxygen fugacity of magmas

2012
Zircon (ZrSiO4) is a durable mineral found in most igneous rocks; it is highly retentive of the trace element concentrations it acquires at crystallisation, and its high initial concentrations of U and Th relative to Pb make it the most important mineral for radiometric dating.
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