GENERALIZED REGULARITIES OF THE VISCOSITY OF MAGMATIC MELTS AT T, P - PARAMETERS OF THE UPPER MANTLE. EXPERIMENTS, MODEL
E.S. Persikov1, P.G. Bukhtiyarov1, A.G. Sokol2, A.N. Kruk2, D.M. Sultanov1.
1Institute of Experimental Mineralogy RAS, Chernogolovka, Russia
2V. S. Sobolev Institute of Geology and Mineralogy Siberian Branch Russian Academy of Sciences
(IGM SB RAS), Novosibirsk, Russia
Keywords: viscosity, structure, basalt, model kimberlite and ultramafic melts, temperature, pressure, upper mantle, model
Abstract
We obtained the experimental and theoretical data on the temperature and pressure dependencies of the viscosity of model ultramafic and basalt melts at mantle thermodynamic parameters. Based on systematic experimental and theoretical studies, we established generalized patterns of the temperature and pressure dependencies of the viscosity of depolymerized magmatic melts (basaltic, model ultramafic and kimberlite) under conditions of the upper mantle. We have established an anomalous and extreme dependence of the viscosity of basaltic melts on pressure: as the pressure increases, the viscosity of such melts decreases, passes through a minimum, and then increases again. In contrast, for depolymerized ultramafic melts, the dependence of their viscosity on pressure corresponds to the theoretical dependence, i.e., as the pressure increases, the viscosity of such melts increases exponentially. A structural - chemical model has been developed for reliable predictions and calculations of the viscosity of magmatic melts in the full range of their basicity, from acidic to ultramafic, at T, P - parameters of the Earth's crust and upper mantle, with an error comparable to the experimental error. Using a computer version of this model, the characteristic features of the change in viscosity of ultramafic and basalt melts as they rise from the mantle to the Earth's crust have been established.
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