摘要
通过脱水反应的平衡热力学计算确定内蒙古兴和－卓资太古宙孔兹岩系变泥砂质岩中变质峰期ａＨ２Ｏ 总体较低， 变化于０．１２～０．４０ 之间， 黑云紫苏片麻岩中ａＨ２Ｏ为０．２０～０．４３。前者的ｌｏｇｆＯ２ 值最高为－ １３～－ １５， 但在有些岩石中极低，（μＨ２ Ｏ／ＸＢｔＭ ｇ ）Ｐ，Ｔ和（μＯ２ ／ＸＢｔＭ ｇ ）Ｐ，Ｔ的系数主要变化于－ ０．２４１～－ ０．３８３ 和－ １．０５２～－ １．８１０，（μＨ２Ｏ ／μＯ２ ）Ｐ，Ｔ的斜率也有一定变化。这些数值变化特征按 “碳质变质”观点不应出现， 主要也不是脱水熔融作用所致， 它们可能与非完全开放系统中Ｈ２Ｏ较ＣＯ２
Based on thermodynamic calculation of dehydration reactions, the activity of H 2O ( a H 2O ) in meta pelitic psammitic rocks of Archaean khondalite series from the studied region during its metamorphic peak has been measured with the value varying from 0 12 to 0 40 Higher a H 2O values of 0 20～0 43 have been obtained from intercalated biotite hypersthene gneiss The fugacity of O 2 in term of log f O 2 in the former rock type is less than -13～-15 The coefficient of ( μ H 2O / X Bt Mg ) P,T and ( μ O 2 / X Bt Mg ) P,T in this rock type is mainly in range of -0 241～ -0 383, and -1 052～-1 810, respectively, and the slop of ( μ H 2O / μ O 2 ) P,T is also variable On the basis of regional geological setting, such characteristics of variation is neither consistent with evidence hoped by the view of “carbonic metamorphism”, nor can be entirely explained by dehydration melting These features may be related to preferably escaping of vapour (formed by dehydration reactions) to CO 2 (produced by oxidation of organic materials from protolith) within a not completely open system
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
1999年第4期493-504,共12页
Acta Petrologica Sinica
基金
国家自然科学基金
关键词
太古宙
孔兹岩
变质峰期
水活度
氧逸度
化学位
Activity of H_2O
Fugacity of O_2
Coefficience of chemical potential
Khondalite series
Inner Mongolia
