Abstract
A garnet-omphacite-kyanite-coesite geothermobarometer is constructed to estimate the peak metamorphic pressure of ultrahigh-pressure (UHP) eclogites. For this we use a quaternary regular solution model for garnet, and propose a new model for sodic pyroxene that assumes double site solid-solution (Na,Ca)M2(Al,Fe3+,Fe2+,Mg)M1Si2O6, where cations in the M2- and the M1-sites mix randomly but with intersite interactions, not only between nearest neighboring cations but also bewteen next nearest neighboring cations. In the new model, overall excess interaction parameters are quantitatively deduced from the previous experimental data and critical temperature, and the activity of the jadeite component agrees reasonbly with that based on the Landau theory. Furthermore, the relations of the calculated order parameter to temperature and composition are consistent with other experimental works. These facts support the usefulness of the new model. Application of our geothermobarometer to kyanite eclogite gave metamorphic conditions around 3.4 GPa and 800°C for both samples from the Dora Maira Massif, Western Alps, and from Rongcheng County, in the Su-Lu region of Eastern China.
| Original language | English |
|---|---|
| Pages (from-to) | 93-102 |
| Number of pages | 10 |
| Journal | Contributions to Mineralogy and Petrology |
| Volume | 130 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 1997 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Geochemistry and Petrology
- Geophysics
Cite this
Thermodynamic modelling of sodic pyroxene solid-solution and its application in a garnet-omphacite-kyanite-coesite geothermobarometer for UHP metamorphic rocks. / Nakamura, Daisuke; Banno, Shohei.
In: Contributions to Mineralogy and Petrology, Vol. 130, No. 1, 1997, p. 93-102.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Thermodynamic modelling of sodic pyroxene solid-solution and its application in a garnet-omphacite-kyanite-coesite geothermobarometer for UHP metamorphic rocks
AU - Nakamura, Daisuke
AU - Banno, Shohei
PY - 1997
Y1 - 1997
N2 - A garnet-omphacite-kyanite-coesite geothermobarometer is constructed to estimate the peak metamorphic pressure of ultrahigh-pressure (UHP) eclogites. For this we use a quaternary regular solution model for garnet, and propose a new model for sodic pyroxene that assumes double site solid-solution (Na,Ca)M2(Al,Fe3+,Fe2+,Mg)M1Si2O6, where cations in the M2- and the M1-sites mix randomly but with intersite interactions, not only between nearest neighboring cations but also bewteen next nearest neighboring cations. In the new model, overall excess interaction parameters are quantitatively deduced from the previous experimental data and critical temperature, and the activity of the jadeite component agrees reasonbly with that based on the Landau theory. Furthermore, the relations of the calculated order parameter to temperature and composition are consistent with other experimental works. These facts support the usefulness of the new model. Application of our geothermobarometer to kyanite eclogite gave metamorphic conditions around 3.4 GPa and 800°C for both samples from the Dora Maira Massif, Western Alps, and from Rongcheng County, in the Su-Lu region of Eastern China.
AB - A garnet-omphacite-kyanite-coesite geothermobarometer is constructed to estimate the peak metamorphic pressure of ultrahigh-pressure (UHP) eclogites. For this we use a quaternary regular solution model for garnet, and propose a new model for sodic pyroxene that assumes double site solid-solution (Na,Ca)M2(Al,Fe3+,Fe2+,Mg)M1Si2O6, where cations in the M2- and the M1-sites mix randomly but with intersite interactions, not only between nearest neighboring cations but also bewteen next nearest neighboring cations. In the new model, overall excess interaction parameters are quantitatively deduced from the previous experimental data and critical temperature, and the activity of the jadeite component agrees reasonbly with that based on the Landau theory. Furthermore, the relations of the calculated order parameter to temperature and composition are consistent with other experimental works. These facts support the usefulness of the new model. Application of our geothermobarometer to kyanite eclogite gave metamorphic conditions around 3.4 GPa and 800°C for both samples from the Dora Maira Massif, Western Alps, and from Rongcheng County, in the Su-Lu region of Eastern China.
UR - http://www.scopus.com/inward/record.url?scp=0031389814&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0031389814&partnerID=8YFLogxK
U2 - 10.1007/s004100050352
DO - 10.1007/s004100050352
M3 - Article
AN - SCOPUS:0031389814
VL - 130
SP - 93
EP - 102
JO - Contributions of Mineralogy and Petrology
JF - Contributions of Mineralogy and Petrology
SN - 0010-7999
IS - 1
ER -