| The Activity of H2O,Fugacity of O2 and Variation of Their Chemical Potential During Metamorphic Peak of the Granulite Complex Near Taipingzhai—Louzishan Region,East Hebei Province |
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| 引用本文： | 卢良兆,董永胜,等.The Activity of H2O,Fugacity of O2 and Variation of Their Chemical Potential During Metamorphic Peak of the Granulite Complex Near Taipingzhai—Louzishan Region,East Hebei Province[J].中国地球化学学报,2001,20(2):97-107. |
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| 作者姓名： | 卢良兆 董永胜 |
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| 作者单位： | [1]CllegeofEarthSciences,JilinUniversity,Changchun130061,China [2]CllegeofEarthSciences,JilinUniversity,Cha |
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| 摘 要： | The thermodynamic calculation of dehydration reacton suggests very low activity of H2O during metamorphic peak of the Archaean granulite complex in the region studied.The αH2O values for Al-rich gneiss and hypersthene biotite gneiss-granulite in the Taipingzhai region are usually between 0.10 and 0.20,and those in the Louzishan region are 0.15-0.25.The fugacity of O2 in terms of lgf O2 in whole region ranges form-8to-14.The average coefficients of (δμH2O/δHMg^Bt)and(δμO2/δXMg^Bt)in the Taipingzhai region are-0.293 and-1.60 respectively,and those in the Louzishan region are-0.364and-1.420.The activity of H2O is very low in the whole region,but its values and other data mentioned above are considerably constant from place to place within a given region,even in rocks of dirrerent lithological characters.However,they show a certain gradient between different regions.Such characteristics are compatible with the genetic mechanism known as“carbonic metamorphism” put forward by Newton et al.,i.e.,the α H2O during the peak stage is controlled by permeation of pervasive CO2 influx of the mantle source,and shows features of external buffering.
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| 关 键 词： | 逸出氧 化学势 河北 麻粒岩 变质作用 水力学 |
| 收稿时间： | 30 June 1992 |
The activity of H2O, fugacity of O2 and variation of their chemical potential during metamorphic peak of the granulite complex near Taipingzhai-Louzishan region, East Hebei Province |
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| Liangzhao Lu,Yongsheng Dong,Xiwen Zhou.The activity of H2O, fugacity of O2 and variation of their chemical potential during metamorphic peak of the granulite complex near Taipingzhai-Louzishan region, East Hebei Province[J].Chinese Journal of Geochemistry,2001,20(2):97-107. |
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| Authors: | Liangzhao Lu Yongsheng Dong Xiwen Zhou |
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| Institution: | (1) Institut für Kristallographie und Petrographie, Swiss Federal Institute of Technology, ETH 8092 Zurich, Switzerland; |
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| Abstract: | The thermodynamic calculation of dehydration reacton suggests very low activity of H2O during metamorphic peak of the Archaean granulite complex in the region studied. The $a_{H_2 O} $ values for Al-rich gneiss and hypersthene biotite gneiss-granulite in the Taipingzhai region are usually between 0.10 and 0.20, and those in the Louzishan region are 0.15–0.25. The fugacity of O2 in terms of $\lg f_{O_2 } $ in the whole region ranges from ?8 to ?14. The average coefficients of $\left( {{{\partial \mu _{H_2 O} } \mathord{\left/ {\vphantom {{\partial \mu _{H_2 O} } {\partial X_{Mg}^{Bt} }}} \right. \kern-0em} {\partial X_{Mg}^{Bt} }}} \right)$ and $\left( {{{\partial \mu _{O_2 } } \mathord{\left/ {\vphantom {{\partial \mu _{O_2 } } {\partial X_{Mg}^{Bt} }}} \right. \kern-0em} {\partial X_{Mg}^{Bt} }}} \right)$ in the Taipingzhai region are ?0.293 and ?1.60 respectively, and those in the Louzishan region are ?0.364 and ?1.420. The activity of H2O is very low in the whole region, but its values and other data mentioned above are considerably constant from place to place within a given region, even in rocks of different lithological characters. However, they show a certain gradient between different regions. Such characteristics are compatible with the genetic mechanism known as “carbonic metamorphism” put forward by Newton et al., i. e., the $a_{H_2 O} $ during the peak stage is controlled by permeation of pervasive CO2 influx of the mantle source, and shows features of external buffering. |
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