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熊店榴辉岩产于大别山西部苏家河构造混杂岩带内,是典型的高压—超高压中温榴辉岩。作者应用岩相学结合阴极发光和扫描电镜方法,较系统地研究了榴辉岩中锆石在岩石中的赋存状态、内部结构及表面特征。锆石主要产于石榴子石等变质矿物内,与主晶界面清晰,具有多晶面等变质锆石特有形貌特征,内部均匀或发育变质生长结构,从而说明它们是变质作用的产物。SHRIMP分析表明,锆石~(206)Pb/~(238)U年龄为335～424Ma,有放射性成因铅丢失现象,因此可以推断424±5Ma代表高压变质事件的最小年龄。结合已有的Sm-Nd全岩和内部等时线、冻蓝闪石~(40)Ar-~(39)Ar及单颗粒锆石U-Pb和~(207)Pb/~(206)Pb年龄资料综合分析,熊店榴辉岩的峰变质年龄应限于424～480Ma之间。这一研究进一步说明大别山存在加里东期榴辉岩。
Xiongdian eclogite is produced in the Sujiahe structural melange belt in western Dabie Mountains, and is a typical high-pressure-high-pressure moderate temperature eclogite. Using petrography combined with cathodoluminescence and scanning electron microscopy, the authors systematically studied the occurrence state, internal structure and surface features of zircons in eclogites. Zircon is mainly produced in the metamorphic minerals such as garnet and has a clear interface with the host grain and unique morphological features such as polymorphic metamorphic zircons and uniform or degenerate growth structures inside, indicating that they are the products of metamorphism. SHRIMP analysis shows that zircon 206 Pb / 238 U age is from 335 to 424 Ma, and there is radioactive lead loss. Therefore, it can be concluded that 424 ± 5Ma represents the minimum age of high-pressure metamorphic events. In combination with the existing Sm-Nd whole rock and its internal isochronal line, the contents of the frozen glaucophane ~ (40) Ar- ~ (39) Ar and single-particle zircon U-Pb and ~ 207 Pb / 206 Pb Comprehensive analysis of age data, Xiongdian eclogite peak metamorphic age should be limited to between 424 ~ 480Ma. This study further illustrates the existence of the Caledonian eclogites in the Dabie Mountains.