xMELTS will greatly expand the covered range of P-T conditions, when compared to MELTS and pMELTS. The original NSF award to Mark Ghiorso and co-workers lead to the development of the LEPR database and a provisional silicate liquid model. As part of an ARRA-funded collaboration, new volume models for garnet and spinel were calibrated at Caltech. We are continuing to work with Mark on extending and improving the thermodynamic solution models used with xMELTS. Eventually the updated solid solution models will be included in various xMELTS-based programs and tools.
The calculators on this site allow users to access the new volume and activity models, as and when they are published (or at least submitted for publication). The web tool is similar to the 'MELTS Supplemental Calculator' and successors. It allows users to input pressure, temperature, and mineral composition; a variety of formats are available. Thermodynamic data (currently just volume) and, if appropriate, ordering state are output and can be used for further calculations. Models available at present are:
Emily A. Hamecher, Paula M. Antoshechkina, Mark S. Ghiorso, and Paul D. Asimow (2013). The molar volume of FeO-MgO-Fe2O3-Cr2O3-Al2O3-TiO2 spinels. Contributions to Mineralogy and Petrology, Volume 165, pp 25-43.
Go straight to the Spinel Volume calculator!
Emily A. Hamecher, Paula M. Antoshechkina, Mark S. Ghiorso, and Paul D. Asimow (in prep). The molar volume of cubic garnets in the system SiO2-Al2O3-TiO2-Fe2O3-Cr2O3-FeO-MnO-MgO-CaO-Na2O. To be submitted to Contributions to Mineralogy and Petrology.
Coming soon... the Garnet Volume calculator!
- For more information on the intended scope of the xMELTS model, once it is finalized, see the 5th FAQ on Mark Ghiorso's MELTS homepage.
- For more information on the various phase property calculators available for solids and liquids in the MELTS and pMELTS models see the alphaMELTS links page.
- For more details about the Caltech - OFM Research calibration effort and the people involved, please see the alphaMELTS 'about us' page.