中国大陆科学钻探主孔超高压榴辉岩中绿辉石结构水研究  

Study of hydroxyl content of omphacite in UHP-eclogite from the main hole of Chinese Continental Scientific Drilling Project.

作　　者：赵旭东[1] 张泽明[1] 

机构地区：[1]中国地质科学院地质研究所,北京100037

出　　处：《岩石学报》2006年第7期2039-2050,共12页Acta Petrologica Sinica

基　　金：中国大陆科学钻探工程项目的部分研究成果;得到国家重点基础研究发展规划(973)项目(2003CB716501);国家自然科学基金项目(40399142和40472036)资助.

摘　　要：本文利用傅立叶(Fourier)变换红外光谱技术对CCSD主孔100-3100米深度范围榴辉岩中的绿辉石结构水含量进行了原位分析。结果表明,所有绿辉石都含有一定的以OH形式存在的结构水,其含量范围为45—784ppm,平均为235ppm。不同榴辉岩绿辉石之间的结构水含量差别较大,而且呈现出明显的空间分布不均一性。相关性分析显示,绿辉石的结构水含量与全岩的MgO、TFeO、Al2O3含量成正相关,与NaO成反相关,与绿辉石的NaO、TFeO含量成负相关,与榴辉岩的峰期变质条件无关;与其它类型榴辉岩相比,多硅白云母榴辉岩中绿辉石的结构水含量较高,平均为339ppm。由此推测,超高压榴辉岩绿辉石中所残留的结构水含量很可能与其峰期结构水含量、矿物化学成分和岩石矿物组成有关。The hydroxyl contents of omphacite in eclogite from the depths of 100m to 3100m of the main hole of Chinese Continental Scientific Drilling Project （CCSD） were analyzed in-situ, using the method of Fourier transform infrared spectroscopy （FTIR）. The results indicate that all the omphacite grains contain a trace amount of structural water as hydroxyl with a range from 45ppm to 784ppm, and the average of 235ppm. The water content of omphacite from eclagite samples is different from each other, showing obviously heterogeneity in the space. The correlation analysis demonstrates that the hydroxyl content of omphacite is correlated positively with the MgO, TFeO and Al2O3 contents, and negatively with the Na2O content of the whole rock and the Na2O and TFeO contents of omphacite, but is not related with the peak metamorphic conditions. Omphacite in phengite eclogite contains more hydroxyl with an average of 339ppm as compared with other types of eclagites. It can be inferred that the hydroxyl content now remained in omphacite may be related to its structurally-bound water content at the peak metamorphism, the mineral composition and the mineral assemblage of the eclogite.

关 键 词：绿辉石 榴辉岩 结构水含量 中国大陆科学钻探工程 

分 类 号：P588.348[天文地球—岩石学]