Viscosity of andesitic melts—new experimental data and a revised calculation model |
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Authors: | Francesco Vetere Harald Behrens Daniel R Neuville |
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Institution: | a Institut für Mineralogie, Universität Hannover, Callinstr. 3, D-30167 Hannover, Germany b Physique des Minéraux et des Magmas, IPGP-CNRS, 4 place Jussieu, F-75252, Paris Cédex 05, France |
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Abstract: | The viscosity of a synthetic andesite-like melt was measured in the low viscosity range (101-106 Pa s) using the falling sphere(s) method and in the high viscosity range (108-1013 Pa s) using parallel-plate viscometry. Falling sphere experiments with melts containing 2.3 and 5.6 wt.% H2O were carried out in an internally heated gas pressure vessel (IHPV) at 500 MPa confining pressure. The sinking velocity of Pt and Pd spheres and in one case of a corundum sphere was used to measure the melt viscosity. In addition, a creep experiment was performed at ambient pressure using a glass containing 2.73 wt.% H2O . A more water-rich glass (5.6 wt.% H2O ) was investigated with a high pressure parallel-plate viscometer at 400 MPa confining pressure in an IPHV. By combining our new data with previous results for a similar melt composition we derived the following expression to describe the viscosity η (in Pa s) as a function of temperature T (in K) and water content w (in wt.%) |
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Keywords: | Viscosity Andesite H2O Unzen Volcano Falling sphere |
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