HR: 12:05h
AN: V51L-08    [PDF]
TI: Non-Arrhenian Multicomponent Melts Viscosity: Extension of the Model.
AU: * Mangiacapra, A
EM: mangia@min.uni-muenchen.de
AF: Universit\`{a} degli Studi di Napoli Federico II, Largo San Marcellino, 27, Napoli, 80138 Italy
AU: * Mangiacapra, A
EM: mangia@min.uni-muenchen.de
AF: Earth and Environmental Sciences, University of Munich, Theresienstrasse 41/III, Munich, 80333 Germany
AU: Giordano, D
EM: daniele_giordano@hotmail.com
AF: Earth and Environmental Sciences, University of Munich, Theresienstrasse 41/III, Munich, 80333 Germany
AU: Giordano, D
EM: daniele_giordano@hotmail.com
AF: Universit\`{a} degli studi di Roma Tre, Via Nomentana,175, Roma, 00161 Italy
AU: Potuzak, M
EM: potuzak@min.uni-muenchen.de
AF: Earth and Environmental Sciences, University of Munich, Theresienstrasse 41/III, Munich, 80333 Germany
AU: Dingwell, D B
EM: dingwell@lmu.de
AF: Earth and Environmental Sciences, University of Munich, Theresienstrasse 41/III, Munich, 80333 Germany
AU: Russell, J K
EM: russell@perseus.geology.ubc.ca
AF: University of British Columbia, 6339 Stores Rd., Vancouver, BC V6T 1Z4 Canada
AB: Viscosity exerts a strong control on many magmatic and petrological processes on micro- and macroscopic scales. Furthermore, knowledge of such a property gives important constraints for structural theories of silicate melts. Giordano and Dingwell (GD)[1] recently described the viscosity of a large number of silicate melts coping a wide compositional range, on the basis of an empirical parameter (SM), sum on a molar basis of the network modifying cations. That model does not consider the contribution of the iron oxidation state to influencing the viscosity. Here, this is rectified. In this experimental study we have doubled (over 700 data) the number of viscosity determinations input into the model provided by [1] extending the compositional basis to further rhyolitic, trachytic, moldavitic, andesitic, latitic, pantelleritic, basaltic and basanitic melt compositions. The effect of Fe$^{2+}$/Fe$^{3+}$ on viscosity has been expressly examined. The temperature-dependence of the new liquid compositions have been investigated at high temperature (1050-1600$\deg$C) and low temperature (616-860$\deg$C) by using a concentric cylinder apparatus and the micropenetration technique, respectively. Fe$^{2+}$/Fe$^{3+}$ ratio has been determined by combining a wet chemistry technique (potassium dichromate titration) with microprobe analysis for each sample, before and after the high and low-T viscometry. Viscosity parameterization along the lines of the GD model, and incorporating the constraint that the high-T viscosities converge to a common value [2], reveal very good agreement with those calculated by [1]. Explicit redox influences appear to be small. [1] D.Giordano, D.B. Dingwell, 2003. Earth Planet. Sci. Lett. 208, 337-349; [2] J.K. Russell, D. Giordano, D.B. Dingwell, 2003, Am. Mineral. 88, 1390-1394.
DE: 8400 VOLCANOLOGY
DE: 8429 Lava rheology and morphology
DE: 8439 Physics and chemistry of magma bodies
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting