恒山灰色片麻岩中变基性岩锆石U-Pb定年  

U-Pb ZIRCON ISOTOPE AGE OF METABASITES FROM HENGSHAN GREY GNEISS

作　　者：常向阳[1] 陈亚东 朱炳泉[1] 

机构地区：[1]中国科学院广州地球化学研究所,广州510640 [2]加拿大安大略皇家博物馆地质年代学实验室

出　　处：《矿物学报》1999年第3期262-266,共5页Acta Mineralogica Sinica

基　　金：国家自然科学基金!49773187

摘　　要：恒山灰色片麻岩中变基性岩的微量锆石U－Pb方法测定结果为：（1850±2）Ma，应代表吕梁期变基性岩墙（脉）的形成时代。三个由不同时代变基性岩构成的Sm－Nd全岩混合等时线年龄结果没有地质意义，不能作为恒山灰色片麻岩中变基性岩包体的形成时代。The U-Pb trace zircon isotope age (1850± 2 Ma) of metabasites from the Hengshangrey gneiss is interpreted as the formation age of metabasite dikes during the Luliang period. Analyses of two samples yield indistinguishable (within the limit of error ), concordant ages of 1850±4 Ma and 1 852± 5 Ma, respectively. Five analyses of the two samples define a linear array with anupper intercept at 1 849+4/-5 Ma and a lower intercept at 636+38/-74 Ma. A pooling of this upper intercept age with the two concordant ages gives an age of 1 850±2 Ma. Three Sin-Nd wholerock isochron ages yielded by the metabasites of various ages cannot be regarded as the formationage of metabasite enclaves from the Hengshan grey gneiss.

关 键 词：变基性岩 灰色片麻岩 锆石 恒山 铀-铅定年 

分 类 号：P588.345[天文地球—岩石学] P597[天文地球—地质学]