冀东峪耳崖和牛心山花岗岩体SHRIMP锆石U-Pb定年及其意义  

SHRIMP U-Pb Dating on Zircon from Yu’erya and Niuxinshan Granite Intrusions in Eastern Hebei Provence

作　　者：罗镇宽[1] 裘有守[1] 关康[1] 苗来成[2] Y.M.Qiu N.J.McNaughton D.I.Groves 

机构地区：[1]天津地质研究院,天津300061 [2]中国科学院地质和地球物理研究所,北京100029 [3]Centre for Strategic Mineral Deposits

出　　处：《矿物岩石地球化学通报》2001年第4期278-285,共8页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：中国-澳大利亚经济技术合作研究基金;国家攀登预选项目 ( 95 预 2 5 )资助

摘　　要：侵入冀东马兰峪复背斜的前寒武岩层中的花岗岩体与区内金矿床有密切的空间关系 ,但成岩时代有争议 ,与金矿床的成因关系不明。本文采用SHRIMP定年方法对含有金矿床的峪耳岩和牛心山岩体进行了锆石U Pb年龄测定 ,获峪耳崖岩体灰白色花岗岩的2 0 6Pb 2 3 8U年龄 175± 1Ma ,肉红色花岗岩的年龄为 174± 3Ma ;牛心山花岗岩的年龄为 172± 2Ma。这 3个年龄在误差范围内可看成是同时代的产物 ,属中生代燕山期。这组年龄限定了金矿化年龄的下限 ,表明金矿化发生在中生代燕山中期后 ,但并不能精确厘定金矿化的年龄 ,因为花岗岩侵入后 ,金矿化之前 ,还有脉岩侵入 ,金矿化与花岗岩本身并无直接的成因关系。Many granitic bodies intruded in the Precambrian strata of Malanyu anticlinorium in eastern Hebei Provence. They are closely related to Au deposits in the area spatially and temporally. However, the rock-forming times and their genetic relation to the Au deposits are controversial. The paper presents the SHRIMP U-Pb dating results on zircons from Au ore-bearing Yuerya and Niuxinshan granitic bodies. The grey white granite and pinkish red granite from Yuerya are aged at 175±1Ma and 174±3 Ma (206 Pb/208U) respectively; granite from Niuxinshan at 172±2 Ma. The results show errors within the same geological times, i.e. Yanshanian Period of Mesozoic Era that defines the lower age limit of the granites and temporal frame of the Au deposits. The precise age of Au mineralization can not be defined because dyke intrusion took place between the granites and Au mineralization. Au mineralization is not directly related to the granites.

关 键 词：锆石 SHRIMP定年 锆石U-PB年龄 峪耳崖花岗岩体 牛心山花岗岩体 冀东 

分 类 号：P597[天文地球—地球化学]