Abstract
A garnet-clinopyroxene geothermometer based on the available experimental data on compositions of coexisting phases in the system MgO-FeO-MnO-Al2O3-Na2O-SiO2 is as follows:
where P is pressure, and Q1, Q2, and K D are given by the following equations
(mole fractions in garnet)
[mole fractions in clinopyroxene Mg = MgSiO3, Fe = FeSiO3, Ca = CaSiO3, Al = (Al2O3-Na2O)] K D = (Fe/Mg) in garnet/(Fe/Mg) in clinopyroxene.
Mn and Cr in clinopyroxene, when present in small concentrations are added to Fe and Al respectively. Fe is total Fe2++Fe3+.
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Abbreviations
- R :
-
gas constant
- T :
-
absolute temperature
- P :
-
pressure
- X :
-
mole fraction
- γ:
-
activity coefficient
- a :
-
activity
- μ:
-
chemical potential
- H :
-
enthalpy
- S :
-
entropy
- A ij C ijk :
-
binary and ternary Margule's parameters
- V :
-
molar volume
- Opx :
-
orthopyroxene
- Cpx :
-
clinopyroxene
- Gar :
-
garnet
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Saxena, S.K. Garnet-clinopyroxene geothermometer. Contr. Mineral. and Petrol. 70, 229–235 (1979). https://doi.org/10.1007/BF00375352
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DOI: https://doi.org/10.1007/BF00375352