胶北粉子山群和荆山群三叠纪变质变形记录:金红石U-Pb年代学证据  

Deformation and Metamorphism of Triassic Fenzishan Group and Jingshan Group in the Jiaobei Massif:Evidence from Rutile U-Pb Geochronology

作　　者：李广旭[1,2] 曹汇[2] 王达[3] 许翠萍[2] 

机构地区：[1]中国地质大学,北京100083 [2]国土资源部大陆动力学重点实验室中国地质科学院地质研究所,北京100037 [3]同位素地质分析实验室美国华盛顿州立大学,普尔曼wa99163

出　　处：《地质学报》2016年第11期3246-3258,共13页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41202153;41472198;41430212);国土资源部公益性行业科研专项经费(编号201211093);中国地质调查局地质调查项目(编号2015020401003;20160102002);中国地质科学院地质研究所中央级公益性基本业务费专项基金(编号J1402);大陆构造与动力学国家重点实验室自主基金(编号Z1401)联合资助的成果

摘　　要：胶北地块粉子山群和荆山群是华北克拉通的重要组成部分,其变质变形作用过程是全面认识华北克拉通性质与演化的关键。前人对粉子山群和荆山群变质变形年代研究的测试对象主要为锆石，报道的年代学数据多集中于1.8-1.9 Ga，认为变质变形作用的时代为古元古代。本文通过对采集自胶北粉子山群和荆山群的2个石榴云母片岩和2个云母片岩样品中独居石及金红石的U-Pb同位素年代测定，揭示了胶北粉子山群和荆山群不仅经历了古元古代（1869±16-1864±14 Ma）变质事件的改造，而且还经历了三叠纪（215.1±4.2-217.8±6.3 Ma）变质变形事件的叠加。通过金红石中Zr温度计计算得出215.1±4.2 Ma，217.7±2.7 Ma和217.8±6.3 Ma的U-Pb年龄对应温度分别为：658℃，667℃和680℃。表明胶北地块部分卷入了三叠纪苏鲁-大别超高压变质带的俯冲-碰撞造山过程，并遭受了角闪岩相变质作用叠加。The metamorphism and deformation process of Fenzishan Group and Jingshan Group in the Jiaobei massif are important for understanding the evolution of North China Craton. Previous geochronological study in this area mainly focused on zircons. The metamorphism and deformation age occurred around Paleoproterozoic because most geochronology data published are around 1.8 ~ 1.9 Ga. Monazite and rutile separated from 2 garnet mica schist and 2 mica schist samples, which were collected from Fenzishan Group and Jingshan Group, were analyzed for U-Pb isotopic age in this study. The results reveal that Fenzishan and Jingshan groups not only experienced the Proterozoic （1869±16~1864±14 Ma） metamorphism, but also overprinted by Triassic deformation and metamorphism （215.1±4.2~217.8±6.3 Ma）. Using Zr thermometry in rutile yielded three U-Pb ages of 215.1±4.2 Ma, 217.7±2.7 Ma and 217.8±6.3 Ma, which correspond to 658℃, 667℃ and 680℃. Our study can conclude that the Jiaobei massif involved in the Triassic Sulu-Dabie HP-UHP subduction-collision orogenic process, superimposed by Triassic amphibolite facies metamorphism and deformation.

关 键 词：胶北地块 粉子山群 荆山群 变质变形 金红石U—Pb年代学 

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