Electron microprobe monazite Th-Pb dating and its constraints on multi-stage metamorphism of low-pressure pelitic granulite from the Jingshan Group in the Jiaobei terrane  

作　　者：ZHOUXiwen WEIChunjing GENGYuansheng ZHANGLifei 

机构地区：[1]InstituteofGeology,ChineseAcademyofGeologicalSciences,Beijing100037,China//TheKeyLaboratoryofOrogenicBeltsandCrustalEvolution,SchoolofEarthandSpaceSciences,PekingUniversity,Beijing100871,China [2]TheKeyLaboratoryofOrogenicBeltsandCrustalEvolution,SchoolofEarthandSpaceSciences,PekingUniversity,Beijing100871,China [3]InstituteofGeology,ChineseAcademyofGeologicalSciences,Beijing100037,China

出　　处：《Chinese Science Bulletin》2005年第10期1009-1015,共7页

基　　金：This work was supported by the National Natural Science Foundation of China(Grant Nos.40402008,40372032 and 40420120135);TRAPOYT of MOE of China;China Postdoctoral Science Foundation.

摘　　要：Monazites from low-pressure pelitic granulite of the Jingshan Group in the Jiaobei terrane were dated by the electron microprobe method. Three stages of metamor- phic age at 1720±15 Ma, 1687±16 Ma and 1568±15 Ma were yielded by constructing age mapping for zoned mona- zites and PbO-ThO2* isochron diagram for unzoned mona- zites, respectively. The first age was interpreted as the age of an early amphibolite-facies metamorphism, the second age as the peak granulite-facies, and the last age as uplifting of the granulite unit. These ages are the first geochronologic data for the low-pressure pelitic granulites in the Jingshan Group, and thus are of important significance when discussing the tectono-metamorphic evolution of the Jiaobei terrane.Monazites from low-pressure pelitic granulite of the Jingshan Group In theJiaobei terrene were dated by the electron microprobe method. Three stages of metamor-phic age at1720 + 15 Ma, 1687 + 16 Ma and 1568 + 15 Ma were yielded by constructing age mapping for zonedmonazites and PbO-ThO_2 isochron diagram for unzoned monazites, respectively. The first age wasinterpreted as the age of an early amphibolite-facles metamorphism, the second age as the peakgranulite-facies, and the last age as uplifting of the granulite unit. These ages are the firstgeochronologie data for the low-pressure pelitic granulites in the Jingshan Group, and thus are ofimportant significance when discussing the tectono-metamorphic evolution of the Jiaobei terrane.

关 键 词：电子微探针 独居石 泥质岩 麻粒岩 变质作用 

分 类 号：P58[天文地球—岩石学]