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Kirschen, Marcus ; Pichavant, Michel:
Internally-consistent thermochemical parameters for the hydrous melt in the system CaAl2Si2O8–NaAlSi3O8–KAlSi3O8–SiO2–H2O.
2000
Veranstaltung: 78. Jahrestagung der Deutschen Mineralogischen Gesellschaft
, 24.-29. September 2000
, Heidelberg.
(Veranstaltungsbeitrag: Kongress/Konferenz/Symposium/Tagung
,
Poster
)
Abstract
The computation of phase equilibrium diagrams of hydrous silicate systems requires a model of the Gibbs free energy of the melt defining the activity of all solution end-members at given composition, pressure, and temperature. Here we present a set of internally consistent thermochemical parameters for the hydrous melt in the five-component system CaAl2Si2O8 - NaAlSi3O8 - KAlSi3O8 - Si4O8 - H2O and its subsystems. Model parameters of the melt were fitted to ca. 850 experimental liquidus and H2O solubility constraints from the literature using mathematical programming techniques and the crystalline and fluid phases as a reference. The Elkins & Grove mixing model [1] and the Haar equation of state [2] were applied for the feldspars and the fluid, respectively. H2O solubility of the feldspars was neglected. Standard state enthalpies and entropies of the solution end-members were bounded to data from [3]; thermal expansion parameters were taken from [4]. Non-ideality of the dry and hydrous melts was approximated with three-parameter Margules excess polynomials for the ten pseudo-binary systems and a Kohler-type extrapolation scheme to the higher order systems [5]. No additional ternary or quaternary excess parameters were required. Using previously unpublished liquidus data near the 5% anorthite composition plane we tested the extrapolation capacity of a solution model fitted to the haplogranite system [6]. A standard state enthalpy and entropy of approximately -290 kJ/mol and 68.4 J/Kmol were obtained for the H2O melt component.
Weitere Angaben
| Publikationsform: | Veranstaltungsbeitrag (Poster) |
|---|---|
| Begutachteter Beitrag: | Ja |
| Institutionen der Universität: | Fakultäten > Fakultät für Ingenieurwissenschaften Forschungseinrichtungen > Institute in Verbindung mit der Universität > Fraunhofer-Zentrum für Hochtemperatur-Leichtbau (HTL) Fakultäten Forschungseinrichtungen Forschungseinrichtungen > Institute in Verbindung mit der Universität |
| Titel an der UBT entstanden: | Nein |
| Themengebiete aus DDC: | 500 Naturwissenschaften und Mathematik > 550 Geowissenschaften, Geologie |
| Eingestellt am: | 03 Jul 2019 07:16 |
| Letzte Änderung: | 03 Jul 2019 07:16 |
| URI: | https://eref.uni-bayreuth.de/id/eprint/49549 |