Browsing ELibrary by Subject "MAGMAS"
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Browsing ELibrary by Subject "MAGMAS"
Now showing items 1-19 of 19
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(1997)High total and fluid pressures develop in the interior of high-viscosity lava domes and in the uppermost parts of the feeding conduit system as a consequence of degassing. Two effects are recognised and are modelled ...
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(2000)Recent numerical models and analog shock tube experiments show that disequilibrium degassing during magma ascent may lead to violent vesiculation very near the surface. In this study a series of decompression experiments ...
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(1999)Numerical models predict that rapid ascent of hydrous magma can lead to supersaturation of dissolved volatile constituents, possibly leading to explosive eruption. We have performed controlled decompression experiments to ...
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(1996)Partial melting experiments were conducted on a natural high-alumina basalt from the Higashi-Izu volcanoes (47.4 wt.% SiO2; 8.3 wt.% MgO) with 1 and 2 wt.% total H2O at 0.5 and 1 GPa, 1125-875oC. The partial melts produced ...
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(2000)A semi-theoretical model is proposed to predict partitioning of noble gases between any silicate liquid and a H2O-CO2 gas phase with noble gas as a minor component, in a large range of pressures (at least up to 300 MPa). ...
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(1998)We present a melt percolation model incorporating finite solid diffusion to provide a quantitative constraint on how melt migrates through the oceanic lower crust at fast-spreading ridge axes. The lower crustal, layered ...
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(2001)The formation of a continuous crystal network in magmas and lavas can provide finite yield strength, τy, and can thus cause a change from Newtonian to Bingham rheology. The rheology of crystal-melt suspensions affects ...
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(1997)We present here the first survey of (231Pa235U) ratios in volcanic rocks; such measurements are made possible by new mass spectrometric techniques. The data place new constraints on the timing and extent of magma source ...
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(1999)When a saturated basaltic magma cools and crystallises in a shallow magma reservoir, gas bubbles may be exsolved from solution, thereby influencing the density, convective mixing and pressure evolution of the melt. In wet ...
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(2001)We present the results of numerical simulations to explore the effects of periodicity of basalt intrusion on the degree and timescales of melting of mafic lower (arc) crust. Melt production as a function of temperature was ...
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(2002)The viscosity of volcanic melts at the glass transition has been determined for 11 compositions ranging from basanite to rhyolite. Determination of the temperature dependence of viscosity, together with the cooling rate ...
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(2001)The viscosity of silicic melts depends strongly on their water content. As bubbles grow in a supersaturated melt, water evaporates from the bubble-melt interface. A diffusive profile develops and leads to steep viscosity ...
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(1999)The physical effects of air or argon bubbles on the rheology of a calcium aluminosilicate melt have been measured at temperatures ranging from 830° to 960°C, at 1 bar pressure. The melt composition is SiO2:64, Al2O3:23, ...
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(1999)Observations of natural eruption products show that different parts of a single magma batch may experience different degassing histories during ascent in a volcanic conduit. In non-explosive eruptions, lava issuing from a ...
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(1998)Evidence of magma mixing is common in the products of explosive felsic eruptions and it is generally accepted as a common mechanism for triggering such events. In order to quantify the potential for magma mixing to trigger ...
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(1998)We propose that the fluid mechanics of magma chamber replenishment leads to a novel process whereby silicic magmas can acquire an important part of their chemical signatures. When flows of basaltic magma enter silicic magma ...
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(2001)It has long been recognized that mare basalts on the Moon are preferentially located both on the Earth-facing hemisphere and within large impact basins. A popular model that accounts for this observation assumes that these ...
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(2001)The 1-atm viscosities of hydrated synthetic iron-free phonolite and trachyte melts are reported between 108.4 and 1013.1 Pa s for water contents between 0 and 5 wt.%. These show a very strong reduction with increasing water ...
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(1997)The effect of temperature and viscosity on the kinetics of bubble growth was measured for a natural water-rich rhyolite melt. The change in volume of a natural crystal-poor calc-alkaline rhyolitic obsidian with an initial ...
Now showing items 1-19 of 19