赞皇变基性岩中锆石的U-Pb定年及其地质意义  

Zircon U-Pb dating of metabasic rocks in the Zanhuang metamorphic complex and its geological significance

作　　者：肖玲玲[1] 王国栋[2] 

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]中国科学院研究生院地球科学学院,北京100049

出　　处：《岩石矿物学杂志》2011年第5期781-794,共14页Acta Petrologica et Mineralogica

基　　金：国家自然科学基金项目(40672129);中国地质科学院地质研究所基本科研业务费专项资金(J1117);中国地质调查局地质调查工作项目(1212011120150)

摘　　要：赞皇变质杂岩区位于阜平杂岩南部,地处华北克拉通中部造山带的中段,和中部带北段杂岩一样,是洞悉华北克拉通前寒武纪基底构造演化历史的一个重要窗口。研究区变基性岩可分为斜长角闪岩和角闪斜长片麻岩两种,二者均以似层状方式产于黑云斜长片麻岩或长英质片麻岩中,斜长角闪岩亦可呈透镜状,二者后期与围岩一起共同经历了高角闪岩相变质作用。斜长角闪岩和角闪斜长片麻岩中普遍存在变质锆石,锆石SIMS U-Pb原位定年获得的207Pb/206Pb谐和年龄表明,赞皇变基性岩记录了约18.5亿年(1 842±21 Ma、1 868±29 Ma)的一次较为广泛的变质作用事件,结合赞皇变质杂岩的构造背景和变质演化特征,推测该期变质作用事件与古元古代末期华北克拉通东部陆块和西部陆块间的俯冲碰撞作用有关。The Zanhuang metamorphic complex is significant for understanding the Precambrian tectonics and evolution of the North China Craton.Metabasic rocks composed of amphibolite and amphibole-bearing plagioclase gneiss as thin layers or lenses are widely distributed within felsic gneisses and biotite-plagioclase gneisses.These metabasic rocks together with country rocks underwent high-amphibolite facies metamorphism,and abundant metamorphic zircons were formed during this thermal event.SIMS U-Pb chronological analysis indicates that metamorphic zircons record peak high-amphibolite facies metamorphism at 1 868~1 842 Ma.These Paleoproterozoic metamorphic ages are largely in accordance with metamorphic ages of ~1 850 Ma produced from high-pressure granulites in the northern segment of the Trans-North China Orogen,indicating that a significant subduction-collision event did occur in the Trans-North China Orogen between the eastern block and the western block during Paleoproterozoic（~1 850 Ma）.

关 键 词：斜长角闪岩 角闪斜长片麻岩 锆石U-PB定年 赞皇 华北中部带 

分 类 号：P597[天文地球—地球化学]