Abstract
P, T, \(X_{{\text{CO}}_{\text{2}} }\)relations of gehlenite, anorthite, grossularite, wollastonite, corundum and calcite have been determined experimentally at P f =1 and 4 kb. Using synthetic starting minerals the following reactions have been demonstrated reversibly
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(1)
2 anorthite+3 calcite=gehlenite+grossularite+3 CO2.
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(2)
anorthite+corundum+3 calcite=2 gehlenite+3 CO2.
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(3)
3anorthite+3 calcite=2 grossularite+corundum+3CO2.
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(4)
grossularite+2 corundum+3 calcite=3 gehlenite+3 CO2.
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(6)
anorthite+2 calcite=gehlenite+wollastonite+2CO2.
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(7)
anorthite+wollastonite+calcite=grossularite+CO2.
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(8)
grossularite+calcite=gehlenite+2 wollastonite+CO2.
In the T, \(X_{{\text{CO}}_{\text{2}} }\)diagram at P f =1 kb two isobaric invariant points have been located at 770±10°C, \(X_{{\text{CO}}_{\text{2}} }\)=0.27 and at 840±10°C, \(X_{{\text{CO}}_{\text{2}} }\)=0.55. Formation of gehlenite from low temperature assemblages according to (4) and (2) takes place at 1 kb and 715–855° C, \(X_{{\text{CO}}_{\text{2}} }\)=0.1–1.0. In agreement with experimental results the formation of gehlenite in natural metamorphic rocks is restricted to shallow, high temperature contact aureoles.
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Hoschek, G. Gehlenite stability in the system CaO-Al2O3-SiO2-H2O-CO2 . Contrib. Mineral. and Petrol. 47, 245–254 (1974). https://doi.org/10.1007/BF00390149
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DOI: https://doi.org/10.1007/BF00390149