Geochronology and trace element geochemistry of zircon,monazite and garnet from the garnetite and/or associated other high-grade rocks:Implications for Palaeoproterozoic tectonothermal evolution of the Khondalite Belt,North China Craton
作者单位：State Key Laboratory of Lithospheric EvolutionInstitute of Geology and GeophysicsChinese Academy of Sciences
会议名称：《中国科学院地质与地球物理研究所2013年度（第13届）学术年会》
会议日期：2014年
学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学]
基 金：financially supported by the research Grant nos.41023009 and 40730315 from the NSFC the National Basic Research Program (Grant no.2012CB4i 6601 ) of China China Postdoctoral Science Foundation(2013M540137)
关 键 词：Khondalite Belt Monazite chemical dating North China Craton Trace element geochemistry Zircon U-Pb dating
摘 要：It is well documented that the Khondalite Belt of the North China Craton formed by the collision of the Yinshan and Ordos Blocks during ca.1.95 Ga,but the onset of the post-collisional exhumation stage has not been well *** garnetite and garnet-bearing quartz-rich lens that are regarded as residue-melt phases occur occasionally in the foliated metasedimentary rocks in the Jining terrane of the Khondalite *** are free of regional gneissosity,and may be generated during the post-collisional exhumation *** U-Pb dating,monazite chemical dating and trace element analyses of zircon,monazite and garnet have been carried out on the garnetites and associated other high-grade metamorphic *** geochronological results reveal a major age group of ca.1890 Ma from the zircon grains/overgrowths and inclusion-type monazites within the garnet poikiloblasts in the *** trace elements analyses show that zircon hosted in the mantle of the garnet poikiloblasts in the garnetite contains the highest HREE and Y contents,whereas zircon hosted in the garnet rims shows higher HREE and Y contents than matrix zircon ***-type monazite in the garnetite shows higher La/Sm ratio than matrix monazite *** garnet poikiloblasts in the garnetite exhibit bell-shaped HREE and Y zoning profiles attributed to Rayleigh fractionation during their *** to garnet poikiloblasts, coronal garnet shows higher Gro,Cr and Li contents,but lower X,Sm,HREE,Zn and Zr contents and weaker Eu negative anomalies,reflecting their different formation *** on evidences from microstructural analyses,REE concentrations and patterns,HREE partition coefficients and the Tiin -zircon thermometer,it is proposed that most of the zircon grains/overgrowths in the garnetite formed coevally with garnet ***,ca.1890 Ma represents the timing of garnet poikiloblast growth during the partial melting of the *** garnet or Zn-ric