ΔG = ΔH - TΔS
Thermodynamic Modeling on Metamorphic Rocks
Thermodynamic modeling on metamorphic rocks is to use computer programs (Theriak-Domino, Perple_X, and ThermoCalc), and integrated internally consistent database and activity-composition relations to calculate mineral stability and pressure-temperature conditions mainly through constructing pseudosections or phase diagrams.
Common Programs
Mineral Solution
Metabasite set (Green et al. 2016)
Metapelite set (White et al. 2014)
Igneous set (Holland et al. 2018)
Metamorphic P-T Phase Diagrams
Binary Phase Diagrams
What can we do with the modeling?
Ternary Phase Diagrams
A P-T pseudosection shows the stability fields for typical metabasite
A T-M(H2O) pseudosection shows the change of mineral stability with temperature and H2O change at P = 22 kbar
A triangle pseudosection for CMS system with H2O saturation, showing the phase reactions in aqueous condition at T = 320 °C and P = 4.6 kbar
and MORE ......
General Comparison of the Three Modeling Programs
Useful links:
Contact:
Ruiguang Pan panr@iupui.edu
Catherine Macris camacris@iupui.edu
IUPUI Earth Sciences
723 W. Michigan St. SL118
Indianapolis, IN 46202
United States
Key References:
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Berman RG (1988) Internally-consistent thermodynamic data for minerals in the system. Na2O-K2O-CaO-MgO-FeO-Fe2O3-Al2O3-SiO2-TiO2-H2O-CO2. J Petrol 29(2):445–522.
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Diener JFA, Powell R (2012) Revised activity-composition models for clinopyroxene and amphibole. J Metamorph Geol 30(2): 131–142.
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Green ECR, White RW, Diener JFA, Powell R, Holland TJB, Palin RM (2016) Activity-composition relations for the calculation of partial melting equilibria in metabasic rocks. J Metamorph Geol 34(9):845–869.
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Holland T, Powell R (2000) AX: A program to calculate activities of mineral end members from chemical analyses (usually determined by electron microprobe).
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Holland T, Powell R (2003) Activity-composition relations for phases in petrological calculations: an asymmetric multicomponent formulation. Contrib Mineral Petrol 145(4):492–501.
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Holland TJB, Powell R (2011) An improved and extended internally consistent thermodynamic dataset for phases of petrological interest, involving a new equation of state for solids. J Metamorph Geol 29(3):333–383.
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Waters DJ, Martin HN (1996) The garnet-Cpx-phengite barometer. Recommended Calibration and Calculation Method. https://www.earth.ox.ac.uk/~davewa/research/eclogites/ecbarcal.html
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White RW, Powell R, Holland TJB (2007) Progress relating to calculation of partial melting equilibria for metapelites. J Metamorph Geol 25(5):511–527.
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White RW, Powell R, Holland TJB, Johnson TE, Green ECR (2014) New mineral activity-composition relations for thermodynamic calculations in metapelitic systems. J Metamorph Geol 32(3):261–286.