The role of H 2 O in silicate melts; II, Thermodynamic and phase relations in the system NaAlSi 3 O 8 -H 2 O to 10 kilobars, 700 degrees to 1100 degrees C

Burnham, Charles W.; Davis, Nicholas F.

doi:10.2475/ajs.274.8.902

Cited by 202 publications

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“…The partial molar heat capacity of water is poorly constrained in the literature. Bouhifd et al (2006) published a value of 85 J mol_1 K_1 for the heat capacity of water for polymerized melts (0 < NBO/T < 0.2), in agreement with the studies of Burnham and Davis (1974) and Clemens and Navrotsky (1987). Recently, a much greater value for the partial molar heat capacity of water of 237 J mol_1 K_1 was determined by the same authors (Bouhifd et al, 2012) for depolymerized melts of synthetic tephritic and foiditic composition (0.86 < NBO/T < 1.51).…”

Section: Heat Capacity Of Water In Silicate Liquidssupporting

confidence: 70%

“…The three-term Maier Kelley equation, based on the additive models of calculation from oxide components, well reproduces the variation of heat capacity of glasses (Cpg) with temperature (Richet, 1987;Bouhifd et al, 2006). Heat capacity measurements on as phase equilibria calculations, theoretical investigation of physical properties of liquids and water exsolution during ascent-driven degassing (e.g., Burnham and Davis, 1974;Burnham and Davis (1974) and Clemens and Navrotsky (1987) determined a partial molar heat capacity for water in hydrous melt of 80 J mol_1 K_1 by calorimetric measurements and thermodynamic calculations on the albite-water system. Furthermore, Clemens and Navrotsky (1987) showed that this value is close to that predicted for pure water at P and T, suggesting that the partial molar heat capacity of water has little dependence on composition.…”

Section: Introductionmentioning

confidence: 99%

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Heat capacity, configurational heat capacity and fragility of hydrous magmas

Genova

Romano

Giordano

et al. 2014

Geochimica et Cosmochimica Acta

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International audienceThe glassy and liquid heat capacities of four series of dry and hydrous natural glasses and magma as a function of temperature and water content (up to 19.9 mol%) were investigated using differential scanning calorimetry (DSC). The analyzed compositions are basalt, latite, trachyte and pantellerite. The results of this study indicate that the measured heat capacity of glasses (Cpg) is a linear function of composition and is well reproduced by the empirical model of Richet (1987). For the investigated glasses, the partial molar heat capacity of water can be considered as independent of composition, in agreement with Bouhifd et al. (2006). For hydrous liquids, the heat capacity (Cpliq) decreases nonlinearly with increasing water content. Previously published models, combined with the partial molar heat capacity of water from the literature, are not able to reproduce our experimental data in a satisfactory way. We estimated the partial molar heat capacity of water (CpH2O) in hydrous magma over a broad compositional range. The proposed value is 41 ± 3 J mol-1 K-1. Water strongly affects the configurational heat capacity at the glass transition temperature [Cpconf (Tg)]. An increases of Cpconf (Tg) with water content was measured for the polymerized liquids (trachyte and pantellerite), while the opposite behavior was observed for the most depolymerized liquids (basalt and latite). Structural and rheological implications of this behavior are discussed in light of the presented results

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Section: Heat Capacity Of Water In Silicate Liquidssupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Heat capacity, configurational heat capacity and fragility of hydrous magmas

Genova

Romano

Giordano

et al. 2014

Geochimica et Cosmochimica Acta

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“…Water affects the extent of melting [e.g., Burnham and Davis, 1974;Hirth and Kohlstedt, 1996;Gaetani and Grove, 1998], the saturation of phases during fractionation, and the delivery of fluid-mobile incompatible elements [Asimow et al, 2004]. Many of these effects are apparent in the average BAB major and trace element compositions.…”

Section: Back-arc Basinsmentioning

confidence: 99%

The mean composition of ocean ridge basalts

Gale

Dalton

Langmuir

et al. 2013

Geochem. Geophys. Geosyst.

140

320

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[1] The mean composition of mid-ocean ridge basalts (MORB) is determined using a global data set of major elements, trace elements, and isotopes compiled from new and previously published data. A global catalog of 771 ridge segments, including their mean depth, length, and spreading rate enables calculation of average compositions for each segment. Segment averages allow weighting by segment length and spreading rate and reduce the bias introduced by uneven sampling. A bootstrapping statistical technique provides rigorous error estimates. Based on the characteristics of the data, we suggest a revised nomenclature for MORB. "ALL MORB" is the total composition of the crust apart from back-arc basins, N-MORB the most likely basalt composition encountered along the ridge >500 km from hot spots, and D-MORB the depleted end-member. ALL MORB and N-MORB are substantially more enriched than early estimates of normal ridge basalts. The mean composition of back-arc spreading centers requires higher extents of melting and greater concentrations of fluid-mobile elements, reflecting the influence of water on back-arc petrogenesis. The average data permit a re-evaluation of several problems of global geochemistry. The K/U ratio reported here (12,340 AE 840) is in accord with previous estimates, much lower than the estimate of Arevalo et al. (2009). The low Sm/Nd and 143 Nd/ 144 Nd ratio of ALL MORB and N-MORB provide constraints on the hypothesis that Earth has a non-chondritic primitive mantle. Either Earth is chondritic in Sm/Nd and the hypothesis is incorrect or MORB preferentially sample an enriched reservoir, requiring a large depleted reservoir in the deep mantle.

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“…Equation (5) is the equation of state for the gas phase, and Eq. (6) represents the mass-flow-rate fraction of the gas when equilibrium gas exsolution on the basis of the solubility curve of H 2 O in a magma (Burnham and Davis, 1974) is assumed. We also assume that temperature change due to expansion is negligible because of the large heat capacity of the liquid magma; therefore, the energy equation is not solved.…”

Section: A Formula For Calculating Porositymentioning

confidence: 99%

A simple formula for calculating porosity of magma in volcanic conduits during dome-forming eruptions

Kozono

Koyaguchi

2010

Earth Planet Sp

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We present a simple formula for analyzing factors that govern porosity of magma in dome-forming eruptions. The formula is based on a 1-dimensional steady conduit flow model with vertical gas escape, and provides the value of the porosity as a function of magma flow rate, magma properties (viscosity and permeability), and pressure. The porosity for a given pressure depends on two non-dimensional numbers ε and θ . The parameter ε represents the ratio of wall friction force to liquid-gas interaction force, and is proportional to the magma viscosity. The parameter θ represents the ratio of gravitational load to liquid-gas interaction force and is inversely proportional to the magma flow rate. Gas escape is promoted and porosity decreases with increasing ε or θ . From the possible ranges of ε and θ for typical magmatic conditions, it is inferred that the porosity is primarily determined by ε at the atmospheric pressure (near the surface), and by θ at higher pressures (in the subsurface region inside the conduit). The porosity near the surface approaches 0 owing to high magma viscosity regardless of the magnitude of the magma flow rate, whereas the subsurface porosity increases to more than 0.5 with increasing magma flow rate.

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The role of H 2 O in silicate melts; II, Thermodynamic and phase relations in the system NaAlSi 3 O 8 -H 2 O to 10 kilobars, 700 degrees to 1100 degrees C

Cited by 202 publications

References 0 publications

Heat capacity, configurational heat capacity and fragility of hydrous magmas

Heat capacity, configurational heat capacity and fragility of hydrous magmas

The mean composition of ocean ridge basalts

A simple formula for calculating porosity of magma in volcanic conduits during dome-forming eruptions

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