Thermodynamic and rheological properties of rhyolite and andesite melts

Neuville, Daniel R.; Courtial, P.; Dingwell, Donald B.; Richet, Pascal

doi:10.1007/bf00698324

Cited by 102 publications

(54 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Across the range of possible glass transition temperatures, there is no evidence for significant changes in the diffusivity mechanisms for any of the components shown. This is consistent with the notion that rhyolite liquids are structurally similar to rhyolite glasses, as evidenced by only minor changes (~5%) in heat capacity across the glass transition (Neuville et al 1993). Hence, there is no reason to believe that the glass transition represents an abrupt barrier to spherulite growth.…”

Section: Do Spherulites Grow Below the Glass Transition?supporting

confidence: 88%

Diffusion-controlled spherulite growth in obsidian inferred from H2O concentration profiles

Watkins

Manga

Huber

et al. 2008

Contrib Mineral Petrol

View full text Add to dashboard Cite

Spherulites are spherical clusters of radiating crystals that occur naturally in rhyolitic obsidian. The growth of spherulites requires diffusion and uptake of crystal forming components from the host rhyolite melt or glass, and rejection of non-crystal forming components from the crystallizing region. Water concentration profiles measured by synchrotron-source Fourier transform spectroscopy reveal that water is expelled into the surrounding matrix during spherulite growth, and that it diffuses outward ahead of the advancing crystalline front. We compare these profiles to models of water diffusion in rhyolite to estimate timescales for spherulite growth. Using a diffusion-controlled growth law, we find that spherulites can grow on the order of days to months at temperatures above the glass transition. The diffusion-controlled growth law also accounts for spherulite size distribution, spherulite growth below the glass transition, and why spherulitic glasses are not completely devitrified.

show abstract

Section: Do Spherulites Grow Below the Glass Transition?supporting

confidence: 88%

Diffusion-controlled spherulite growth in obsidian inferred from H2O concentration profiles

Watkins

Manga

Huber

et al. 2008

Contrib Mineral Petrol

View full text Add to dashboard Cite

show abstract

“…The P2O5-bearing liquids remain "strong" in the sense of Angell (1984) whereas the others become increasingly "fragile". Richet and co-workers (Richet, 1984;Richet et al, 1986 ;Neuville et al, 1992) have argued that the entropy-based theory of Adam & Gibbs (1965) furnishes a powerful model for the composition-and temperature-dependence of silicate melt viscosity. In the context of that theory, the temperature-dependence of the conflgurational entropy would be expected to be small for the case of the present P2O5-bearing liquids.…”

Section: Resultsmentioning

confidence: 99%

The effect of P2O5 on the viscosity of haplogranitic liquid

Dingwell¹,

Knoche²,

Webb³

1993

ejm

Self Cite

View full text Add to dashboard Cite

: The effect of P2O5 on the viscosity of a haplogranitic (K2O-Na2O-AhO3-SiO2) liquid has been determined at 1 atm pressure in the temperature interval of 700 -1650°C. Viscosity measurements of a haplogranite, haplogranite + 5.1 wt.% P2O5 and haplogranite + 9.5 wt.% P2O5 have been performed using the concentric cylinder and micropenetration methods.The viscosity of haplogranite liquid decreases with the addition of P2O5 at all temperatures investigated. The viscosity decrease is nonlinear, with the strongest decrease exhibited at low P2O5 concentration. The temperaturedependence of the viscosity of all the investigated liquids is Arrhenian, as is the case for P2O5 liquid. The Arrhenian activation energy is slightly lower in the P2O5-bearing liquids than in the P205-free haplogranite with the result that the effect of P2O5 on viscosity is a (weak) function of temperature. At temperatures corresponding to the crystallization of phosphorus-rich granitic and pegmatitic systems the addition of 1 wt.% of P2O5 decreases the viscosity 0.2 logio units.The effect of P2O5 on haplogranitic melt viscosity is much less than that for B2O3, F2O-1 on the same melt composition (Dingwell et al, 1992 and this study). This implies that P2O5 concentration gradients in high-silica melts during, for example, phosphate mineral growth or dissolution in granitic magmas, will not significantly influence melt viscosity.

show abstract

“…We assume constant water vapor heat capacity in the numerical model at values appropriate for the final P-T conditions of numerical runs because it is at this point that water vapor mass is at a maximum. We use published values for heat capacity of magmatic melts [Neuville et al, 1993;Richet and Bottinga, 1986] 8. Heat of vitrification and vitrification temperature have been reliably estimated only for rhyolitic melts [Neuville et al, 1993;Bottinga, 1984, 1986].…”

Section: T-•oo In (A28)mentioning

confidence: 99%

“…We use published values for heat capacity of magmatic melts [Neuville et al, 1993;Richet and Bottinga, 1986] 8. Heat of vitrification and vitrification temperature have been reliably estimated only for rhyolitic melts [Neuville et al, 1993;Bottinga, 1984, 1986].…”

Section: T-•oo In (A28)mentioning

confidence: 99%

Dynamics and energetics of bubble growth in magmas: Analytical formulation and numerical modeling

Proussevitch¹,

Sahagian²

1998

J. Geophys. Res.

214

154

View full text Add to dashboard Cite

Abstract. We have developed a model of diffusive and decompressive growth of a bubble in a finite region of melt which accounts for the energetics of volatile degassing and melt deformation as well as the interactions between magmatic system parameters such as viscosity, volatile concentration, and diffusivity. On the basis of our formulation we constructed a numerical model of bubble growth in volcanic systems. We conducted a parametric study in which a saturated magma is instantaneously decompressed to one bar and the sensitivity of the system to variations in various parameters is examined. Variations of each of seven parameters over practical ranges of magmatic conditions can change bubble growth rates by 2-4 orders of magnitude. Our numerical formulation allows determination of the relative importance of each parameter controlling bubble growth for a given or evolving set of magmatic conditions. An analysis of the modeling results reveals that the commonly invoked parabolic law for bubble growth dynamics R -t 1/2 is not applicable to magma degassing at low pressures or high water oversaturation but that a logarithmic relationship R -log(t) is more appropriate during active bubble growth under certain conditions. A second aspect of our study involved a constant decompression bubble growth model in which an initially saturated magma was subjected to a constant rate of decompression. Model results for degassing of initially water-saturated rhyolitic magma with a constant decompression rate show that oversaturation at the vent depends on the initial depth of magma ascent. On the basis of decompression history, explosive eruptions of silicic magmas are expected for magmas rising from chambers deeper than 2 km for ascent rates > 1-5 m s-1.

show abstract

Thermodynamic and rheological properties of rhyolite and andesite melts

Cited by 102 publications

References 34 publications

Diffusion-controlled spherulite growth in obsidian inferred from H2O concentration profiles

Diffusion-controlled spherulite growth in obsidian inferred from H2O concentration profiles

The effect of P2O5 on the viscosity of haplogranitic liquid

Dynamics and energetics of bubble growth in magmas: Analytical formulation and numerical modeling

Contact Info

Product

Resources

About