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Viscosity of magmatic liquids: A model

Viscosity of magmatic liquids: A model,10.1016/j.epsl.2008.03.038,Earth and Planetary Science Letters,Daniele Giordano,James K. Russell,Donald B. Ding

Viscosity of magmatic liquids: A model   (Citations: 77)
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The viscosity of silicate melts controls magma transport dynamics, eruption style and rates of physicochemical processes (e.g., degassing, crystallization) in natural magmas. Thus a comprehensive viscosity model for magmatic liquids has long been a goal of earth scientists. Here we present a model that predicts the non-Arrhenian Newtonian viscosity of silicate melts as a function of T and melt composition, including the rheologically important volatile constituents H2O and F. Our model is based on >1770 measurements of viscosity on multicomponent anhydrous and volatile-rich silicate melts. The non-Arrhenian T-dependence of viscosity is accounted for by the VFT equation [log η=A+B/(T(K)−C)]. The optimization assumes a common, high-T limit (A) for silicate melt viscosity and returns a value for this limit of −4.55 (+0.2) (e.g., log η~10−4.6 Pa s). All compositional dependence is ascribed to the parameters B and C and is accounted for by an additional 17 model coefficients. Our model is continuous in composition- and temperature-space and predicts the viscosity of natural volatile-bearing silicate melts (SiO2, Al2O3, TiO2, FeOtot, CaO, MgO, MnO, Na2O, K2O, P2O5, H2O, F2O−1) over fifteen log units of viscosity (10−1–1014 Pa s). The model for viscosity can also predict other transport properties including glass transition temperatures (Tg) and melt fragility (m). We show strong systematic decreases in Tg and m with increasing volatile content. This pattern has implications for predicting styles of volcanic eruption and understanding silicate melt structure. Our model transforms a quarter-century of experimental study of melt viscosities, into a parameterisation having a predictive capacity that makes it relevant to diverse fields of research including: volcanology, geophysics, petrology and material sciences.
Journal: Earth and Planetary Science Letters - EARTH PLANET SCI LETT , vol. 271, no. 1, pp. 123-134, 2008
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    • ... 3a and Supplementary Data 1,2) were used to calculate viscosities with the equations of ref...

    Luca Caricchiet al. Melt migration in basalt columns driven by crystallization-induced pre...

    • ...The data are compared with the prediction of general viscosity models of Hui and Zhang (2007) and Giordano et al. (2008), and the implications for pegmatitic processes are discussed...
    • ...Two recently developed non-Arrhenian models taking compositional variations into account are available to calculate silicate melt viscosities: the model of Hui and Zhang (2007) and the model of Giordano et al. (2008)...
    • ...The model of Giordano et al. (2008) does not include Li and B but, in contrast to the model of Hui and Zhang (2007), P and F are taken into account...
    • ...Fig. 4 Comparison between the measured viscosities from this study and calculated viscosities after Giordano et al. (2008), referred to as G08...
    • ...PEG0-2a). This comparison demonstrates that even the model of Giordano et al. (2008) which includes P and F is not well calibrated for highly evolved melt compositions like...

    Alexander Bartelset al. Viscosity of flux-rich pegmatitic melts

    • ...Although the viscosity of a given melt can span several orders of magnitude according to its temperature, the viscosity of the silicone oil is within the range expected for low viscositymagmasatsubliquidustemperature[McBirney and Murase, 1984; Spera, 2000; Giordano et al., 2008]...

    C. Cimarelliet al. Rheology of magmas with bimodal crystal size and shape distributions: ...

    • ...In our experiments, such melts are highly silicic (SiO2 C68.5%; Fig. 7). Hence, they are expected to be highly viscous (for the 850� C experimental melt, and using a theoretical water content of 5 wt%, g = 10 4.4 Pa.s, when calculated using Giordano et al. 2008)...

    Juergen Koepkeet al. Hydrous partial melting in the sheeted dike complex at fast spreading ...

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