A thermodynamic model for silicate melt in CaO–MgO–Al2O3–SiO2 to 50 kbar and 1800 °C

Green, E. C. R. and Holland, T. J. B. and Powell, R. (2012) A thermodynamic model for silicate melt in CaO–MgO–Al2O3–SiO2 to 50 kbar and 1800 °C. Journal of Metamorphic Geology, 30 (6). pp. 579-597. ISSN 0263-4929 DOI https://doi.org/10.1111/j.1525-1314.2012.00982.x

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A fully thermodynamic model for mafic melt in CaO–MgO–Al2O3–SiO2 (CMAS) has been calibrated, for calculation of melting equilibria in the pressure range 0–50 kbar. It is intended as a preliminary step towards a large-system melt model, suitable for exploring melting, melt loss and crystallization processes in a wide range of natural rock compositions. Calibration was performed with attention to the model's behaviour in its compositional subsystems, as a rigorous test of model structure and parameterization. The model is consistent with the latest Holland & Powell thermodynamic data set, and can therefore be used to calculate phase relations in conjunction with the many solid-phase activity–composition models written for the data set. Model calculations successfully reproduce experimental melting reactions in CMAS spinel lherzolite and garnet lherzolite assemblages, as well as sapphirine- and kyanite-bearing assemblages, at moderate to high pressure. Thermodynamically sensitive features, such as thermal divides are also recovered. However, some changes to the model structure will be required before the model can describe the full range of mafic and ultramafic melt compositions known from experiment at low pressures.

Item Type: Article
Uncontrolled Keywords: 2012AREP; IA64;
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Journal or Publication Title: Journal of Metamorphic Geology
Volume: 30
Page Range: pp. 579-597
Identification Number: https://doi.org/10.1111/j.1525-1314.2012.00982.x
Depositing User: Sarah Humbert
Date Deposited: 14 Sep 2012 13:57
Last Modified: 23 Jul 2013 10:04
URI: http://eprints.esc.cam.ac.uk/id/eprint/2592

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