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Melting of β-quartz up to 2.0 GPa and thermodynamic optimization of the silica liquidus up to 6.0 GPa |
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| Authors: | Pierre Hudon In-Ho Jung Don R Baker |
| Institution: | a Department of Earth and Planetary Sciences, McGill University, 3450 rue Université, Montreal, QC, Canada H3A 2A7 b Centre for Research in Computational Thermochemistry, École Polytechnique de Montréal, P.O. Box 6079, Succursale Centre-Ville, Montreal, QC, Canada H3C 3A7 |
| Abstract: | Melting relations of β-quartz were experimentally determined at 1.0 GPa (1900±20 °C), 1.5 GPa (2033±20 °C), and 2.0 GPa ( 2145±20 °C) using a new high-pressure assembly in a piston–cylinder apparatus and substantial differences were found with data previously reported. The new melting data of β-quartz were combined and optimized with all available thermodynamic, volumetric, and phase equilibria data for β-cristobalite, β-quartz and coesite to produce a P–T liquidus diagram for silica valid up to 6.0 GPa. Using the new optimized thermodynamic parameters, the invariant point β-cristobalite+β-quartz+liquid and β-quartz+coesite+liquid were determined to lie at 1687±17 °C and 0.457 GPa, and 2425±25 °C and 5.00 GPa, respectively. |
| Keywords: | SiO2 β-Quartz β-Cristobalite Coesite Silica phase diagram Thermodynamic optimization |
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