辽宁省清原县南口前岩体锆石U-Pb年代学、地球化学及Hf同位素  

Zircon U-Pb Geochronolog,Geochemistry and Hf Isotopes of Nankouqian Granitic Intrusion in Qingyuan Region,Liaoning Province

作　　者：刘金龙[1] 孙丰月[1] 张雅静[1] 马芳[2] 刘峰旭 曾乐[1] 

机构地区：[1]吉林大学地球科学学院,吉林长春130061 [2]吉林省地质资料馆,吉林长春130061

出　　处：《地球科学（中国地质大学学报）》2016年第1期55-66,共12页Earth Science-Journal of China University of Geosciences

基　　金：全国危机矿山接替资源找矿项目(Nos.200823003;200623018);中国地质调查局地质大调查项目(No.1212010630708)

摘　　要：华北板块周边地区板块的俯冲与碰撞对华北后来的岩石圈破坏可能产生了重要影响.对南口前岩体进行了锆石LA-ICP-MS U-Pb年代学和岩石地球化学研究,确定其时代及形成的构造背景.测年结果表明,岩石为晚三叠世(224±1Ma)岩浆侵入的产物.地球化学研究表明岩石为高钾钙碱性系列,A/CNK值为0.98~1.07,属准铝质-过铝质花岗岩类.高Sr(394×10^(-6)~545×10^(-6)),低Yb(0.61×10-6~0.93×10^(-6)),判断岩石属于埃达克岩类.岩石的ε_(Hf)(t)值为-13.2^-6.9,二阶段模式年龄(T_(DM2))变化于1 669~1 825Ma之间,判断岩石源于元古代地壳岩石的部分熔融.综合前人研究成果,认为岩石形成于古亚洲洋闭合后的造山后拉张环境.LA-ICP-MS zircon U-Pb dating and geochemical data of the Nankouqian granitic intrusion were studied to determine its formation time and tectonic background. The zircon U-Pb dating results indicate that the granitic pluton was formed in the Late Triassic （2244-1 Ma）. The granite shows calc-alkaline and metaluminous to weakly peraluminous affinities, with A/CNK ratio ranging from 0.98 to 1.07. The granitic pluton has features similar to adakitic rock with high Sr （394×10^-6-545×10^-6 ） and low Yb （0.61×10^-6-0.93×10^-6）. The in s itu zircon e Hf （t） value varies from -13.2 to -6.9, and a two-stage model age （Tara） varies from 1 669 to 1 825 Ma. These characteristics suggest that the primary magma was derived from partial melting of primarily Proterozoic lower crustal materials. Considering the regional tectonic evolution, we suggest the granites formed in the post-orogenic extension setting which could be related to the closure of the Paleo-Asian Ocean.

关 键 词：锆石U-Pb年龄 岩石地球化学 锆石HF同位素 埃达克岩 南口前 华北 岩石学 

分 类 号：P581[天文地球—岩石学]