江苏东海县磨山片麻状碱性花岗岩锆石SHRIMP定年研究  

Zircon Shrimp Dating of the Gneissic Alkaline Granite from Moshan,Donghai,Jiangsu Province

作　　者：夏斌[1] 李建峰[1] 张玉泉[1] 何观生[1] 王敏[1] 徐力峰[1] 杨之青[2] 

机构地区：[1]中国科学院广州地球化学研究所边缘海地质重点实验室,广州510640 [2]北京离子探针中心,北京100037

出　　处：《地质学报》2008年第8期1052-1056,共5页Acta Geologica Sinica

基　　金：国家自然科学基金重点项目(编号40534019)资助成果

摘　　要：对东海县磨山片麻状碱性花岗岩中变质锆石和变质复合锆石进行SHRIMP U-Pb定年:①对变质锆石和变质复合锆石的新壳共测定8个点,其206Pb/238U加权平均年龄为212±3.6Ma(MSWD=7.55),反映了磨山片麻状碱性花岗岩的变质时间,即成岩时间,属于印支期,相当于晚三叠世;②变质复合锆石的老核(继承锆石),多为发育有规则韵律环带的岩浆碎屑锆石,对其中3个颗粒进行了测定,U-Pb年龄分别为866Ma、378Ma和370Ma,暗示其来源是异地多时代的。同时还表明其寄主岩的原岩应是沉积岩,其时代不会早于晚古生代。This study carried out U-Pb SHRIMP dating on the metamorphic zircons and metamorphic compound zircons from the gneissic alkaline granite, Moshan, Donghai. Eight points on the metamorphic zircons and metamorphic compound zircons have been tested, and yielded an weighed average ^206Pb/^238U age of 212± 3.6 Ma（MSWD=7.55）. This indicates that the metamorphic time of the Moshan gneissic alkaline granite, i.e. the age of the diagenesis, belongs to late Triassic （Indo-china epoch）. The old cores of the metamorphic compound zircons （inherited zircon） are magmatic clastic ones in which rhythmic circles were developed. Dating on three zircons yielded U-Pb age of 866 Ma, 378 Ma and 370 Ma, respectively, implying that they the zircons are allochthonous and polygenetic and protolith of host rock should be probably sedimentary rock, formation of which should be later than Late Paleozoic.

关 键 词：锆石 U-PB年龄 片麻状碱性花岗岩 磨山 东海县 江苏省 

分 类 号：P597.3[天文地球—地球化学] P588.121[天文地球—地质学]