P. G. Bukhtiyarov

Water diffusion in basalt and andesite melts under high pressures

Water diffusion is one of the most important characteristics of many processes dealt with in magmatic geochemistry, petrology, and volcanology. We have experimentally examined water diffusion in Fe-free andesite and basalt melts (stoichiometric mixtures of the minerals albite + diopside + wollastonite) at 3 and 100 MPa, 1300×C, up to approximately 4 wt % water in the melts, and a total (lithostatic) pressure of 100 MPa on a high gas pressure apparatus equipped with a unique internal device. The experiments were conducted simultaneously with the use of two different methods: diffusion hydration and couples. Water solubility in the melts and water concentrations along the diffusion profiles (CH2O) were determined by quantitative IR microspectroscopy, using the Beer-Lambert law. A structural chemical model is proposed for calculating and predicting the concentration dependence of the molar absorption coefficient of the hydroxyl group and water molecules in andesite and basalt glasses. The diffusion coefficients of water (DH2O) are derived by the mathematical analysis of concentration profiles and the analytical solution of the second Fick diffusion law. Preliminary results indicated DH2O is roughly one order of magnitude higher in basaltic melts than in andesitic ones (at the same temperatures and PH2O) and significantly (exponentially) increases with increasing water concentrations in andesitic and basaltic melts. The newly obtained experimental data are proved to be fully consistent with the results obtained on the DH2O dependence on CH2O in melts of acid rocks (rhyolite and obsidian). The derived quantitative dependence between DH2O and melt viscosity is used to develope principles of a new method for predicting and calculating the temperature, concentration, and pressure dependences of DH2O in magmatic melts of the of acid-basic series (up to 3 wt % CH2O) at crustal T, P parameters.

Concentration dependence of water diffusion in obsidian and dacitic melts at high-pressures

The diffusion of water in natural obsidian and model dacitic melts (Ab90Di8Wo2, mol %) has been studied at water vapor pressure up to 170 MPa, temperatures of 1200°C, H2O contents in melts up to ∼6 wt % using a high gas pressure apparatus equipped with a unique internal device. The experiments were carried out by a new low-gradient technique with application of diffusion hydration of a melt from fluid phase. The water solubility in the melts and its concentration along

Gold transport during magmatic degassing: Model experiments

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Eocene accretion at Kamchatka and a pulse of mantle plume magmatism

diffusion profiles were determined using IR microspectrometry by application of the modified Bouguer-Beer-Lambert equation. A structural-chemical model was proposed to calculate and predict the concentration dependence of molar absorption coefficients of the hydroxyl groups (OH−) and water molecules (H2O) in acid polymerized glasses (quenched melts) in the obsidian-dacite series. The water diffusion coefficients

Distribution of light alkanes in the reaction of graphite hydrogenation at pressure of 0.1–7.8 GPa and temperatures of 1000–1350°C

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Gold Dissolution in Dry Salt Melts in the Presence of SiO2 as a Function of Р(O2)

were obtained by the mathematical analysis of concentration profiles and the analytical solution of the second Fick diffusion law using the Boltzman-Matano method. It was shown experimentally that

Experimental study of water diffusion in haplobasaltic and haploandesitic melts

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Change in the viscosity of kimberlite and basaltic magmas during their origin and evolution (prediction)

exponentially increases with a growth of water concentration in the obsidian and dacitic melts within the entire range of diffusion profiles. Based on the established quantitative correlation between

Viscosity of hydrous kimberlite and basaltic melts at high pressures

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Diffusion of Water in Silicate Melts

and viscosity of such melts, a new method was developed to predict and calculate the concentration, temperature, and pressure dependences of