山西青尖坡石英二长岩锆石U-Pb年龄及其地质意义  

Zircon U-Pb age and geological significance of quartz monzonite from Qingjianpo, Shanxi Province

作　　者：杨全林[1] 叶枫[1,2] 董国臣[2] YANG Quanlin;YE Feng;DONG Guochen(Shanxi Institute of Geological Survey,Taiyuan 030006,Shanxi,China;School of Earth Sciences and Resources,China University of Geosciences (Beijing),Beijing 100083,China)

机构地区：[1]山西省地质调查院,山西太原030006 [2]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《地质通报》2019年第9期1501-1510,共10页Geological Bulletin of China

基　　金：中国地质调查局项目《1∶25万大同市(K49C004004)偏关县(J49C001003)幅区调修测》(编号：基[2010]矿评01-11-07号)

摘　　要：通过对华北克拉通北缘青尖坡石英二长岩锆石U-Pb同位素年龄分析,并结合相关主量和稀土元素数据探讨其地质意义。研究表明,石英二长岩LA-ICP-MS锆石U-Pb同位素年龄为241.1±1.7Ma,为早中三叠世岩浆活动的产物。岩石具有富K、Na、Si、Al,贫Mg、Ca、Ti等特征,为高钾碱性钾玄岩系列,属于过铝质花岗岩类;轻稀土元素相对富集,重稀土元素相对亏损,具有稳定的弱负Eu异常。总体为I型花岗岩成因,但兼具S型花岗岩的特征。青尖坡石英二长岩为中下地壳部分熔融成因,有地幔物质参与,为华北克拉通北缘三叠纪碱性岩带的组成部分,形成于晚造山-造山后的伸展构造环境。In this paper, based on the study of Qingjianpo quartz monzonite of zircon U- Pb isotope age, and combine with the major element data and rare earth elementdata, the authors investigated its geological significance. The LA-ICP-MS zircon U-Pb isotopic age of quartz monzonite is 241.1±1.7Ma, revealing that it is a product of the Early-Middle Triassic magmatism. The rock is enriched in K, Na, Si, Al and depleted in Mg, Ca, Ti, belonging to high calc alkaline shoshonite series and peraluminous granitoid. The rock exhibits the enrichment of LREE relative to HREE, and Eu shows weak negative anomaly. The genetic type of Qingjianpo quartz monzonite is I-type granite. with some features of S-type granites. Qingjianpo quartz monzonite characteristics indicate that the rock was formed from partial melting of the mid-lower crust, with the addition of mantle material. Qingjianpo quartz monzonite is a part of the alkaline magmatic belt of Middle Triassic on the northern margin of North China Craton, and it was formed in the extensional tectonic environment of late orogenic-post-orogenic activity.

关 键 词：石英二长岩 早中三叠世 华北克拉通北缘 构造背景 青尖坡 

分 类 号：P588.121[天文地球—岩石学] P597.3[天文地球—地质学]