中条山地区绛县群和中条群沉积时限:夹层斜长角闪岩SIMS锆石U-Pb年代学证据  

Formation ages of the Jiangxian and Zhongtiao groups in the Zhongtiao Mountain region,North China Craton: Insights from SIMS U-Pb dating on zircons of intercalated plagioclase amphibolites

作　　者：刘玄[1] 范宏瑞[1] 邱正杰 杨奎锋[1] 胡芳芳[1] 郭双龙[3] 赵凤春[3] 

机构地区：[1]中国科学院地质与地球物理研究所矿产资源重点实验室,北京100029 [2]中国科学院大学,北京100049 [3]中条山有色金属集团有限公司,垣曲043700

出　　处：《岩石学报》2015年第6期1564-1572,共9页Acta Petrologica Sinica

基　　金：国家重点基础研究发展计划"973"项目(2012CB416605);国家自然科学基金项目(41402083)联合资助

摘　　要：中条山地区出露大量早前寒武纪岩石,是认识华北克拉通晚太古代至早元古代大地构造演化的关键地区。绛县群变质陆缘碎屑-火山岩及中条群变质陆缘碎屑-碳酸盐岩建造是该区最主要的地层单元,同时也是一系列铜矿床的赋矿围岩。目前,对于二者的形成时代仍缺乏直接证据。本文通过高精度的二次离子质谱锆石U-Pb定年,厘定了绛县群和中条群中的斜长角闪岩夹层分别形成于-2189Ma和-2086Ma。结合已有同位素资料,我们认为绛县群变质沉积-火山岩系可能形成于ca.2160-2190Ma,而中条群中段的大理岩和黑色片岩系（余元下组和篦子沟组）形成于ca.2059-2086Ma之间。另外,岩石组合和矿化类型指示,中条山地区在ca.2090-2190Ma可能经历了两次裂谷事件。Zhongtiao Mountain region,located at the southern edge of the North China Craton（ NCC）,contains voluminous outcrops of Early Proterozoic rocks,and it has been considered as an important area for investigating the tectonic evolution of the NCC.Jiangxian Group consisting of metamorphosed continental clastic to volcanic rocks and Zhongtiao Group comprising metamorphosed terrestrial clastic rocks and carbonate are the two major rock units within this region,and their formation ages remains elusive. We report new results of U-Pb dating on zircons from two intercalated plagioclase amphibolites by secondary ion mass spectrometry（ SIMS）,which suggest the Jiangxian and Zhongtiao groups were formed at ca. 2160 - 2190 Ma and ca. 2059 - 2086 Ma,respectively.Combing other evidences,including rock assemblages and mineralization styles,we favor the idea that Zhongtiao Mountain region experienced two episodes of rifting during the Early Proterozoic period.

关 键 词：中条山 绛县群 中条群 斜长角闪岩 SIMS锆石U-Pb 华北克拉通 

分 类 号：P597.3[天文地球—地球化学]