内蒙古济沁河林场晶洞花岗岩锆石U-Pb年龄及地球化学特征  

ZIRCON U-Pb AGES AND GEOCHEMISTRY OF MIAROLITIC GRANITES IN JIQINHE LINCHANG AREA,INNER MONGOLIA

作　　者：吴新伟[1,2] 李世超[1] 江斌[1,2] 张渝金[1,2] 郭威[1,2] 崔天日[2] 李伟[2] 司秋亮[2,3] 李林川[1,2] WU Xin-wei LI Shi-chao JIANG Bin ZHANG Yu-jin GUO Wei CUI Tian-ri LI Wei SI Qiu-liang LI Lin-chuan(College of Earth Sciences, Jilin University, Changchun 130061, China Shenyang Institute of Geology and Mineral Resources, CGS, Shenyang 110034, China College of Resources and Civil Engineering, Northeastern University, Shenyang 110819, China)

机构地区：[1]吉林大学地球科学学院,吉林长春130061 [2]中国地质调查局沈阳地质调查中心(沈阳地质矿产研究所),辽宁沈阳110034 [3]东北大学资源与土木工程学院,辽宁沈阳110819

出　　处：《地质与资源》2017年第3期234-244,309,共12页Geology and Resources

基　　金：国家自然科学基金项目(41340024,41272223);中国地质调查局项目(1212011120664,DD20160047)

摘　　要：对大兴安岭中部济沁河林场地区晶洞二长花岗岩进行了锆石U-Pb同位素年代学及地球化学研究,并对其成岩时代、成因及构造意义进行讨论.从阴极发光图像上来看,该晶洞二长花岗中锆石具有典型岩浆成因的振荡生长环带,高Th/U比值也印证了其岩浆成因.LA-ICP-MS锆石U-Pb定年结果显示,岩体形成于113.1~115.1 Ma的早白垩世晚期.二长花岗岩具有高硅、富碱的特征,Eu异常较小,弱过铝质,富集U、Th,强烈亏损P和Ti,微量元素中富集Rb、Th、La、Zr、Hf,而亏损Ba、Sr、P、Ti.上述特征表明晶洞花岗岩是高分异的I型花岗岩,其形成于华北板块、西伯利亚板块、北美板块和古太平洋板块四者汇聚之后的后碰撞伸展构造环境.With study on the geochemistry and zircon U-Pb isotopic geochronology of the miarolitic granites in middle Daxinganling Mountains,the age,petrogenesis and tectonic implication are discussed. The zircons from the miarolitic granites show oscillatory growth zonation and high Th/U ratios,indicating a magmatic origin. The LA-ICP-MS U-Pb age of 113.1~11.1 Ma suggests that the rock was formed in the late stage of Early Cretaceous. The granites are characterized by high SiO2 and rich alkali,with negative Eu anomaly and weak peraluminous. The trace elements are enriched in Rb,Th,La,Zr and Hf and depleted in Ba,Sr,P and Ti. It is concluded that the miarolitic granites belong to highly fractionated I-type,formed in a post-collisional extensional setting after the convergence of North China,Siberian,North American and Pacific plates.

关 键 词：大兴安岭 晶洞花岗岩 年代学 I型花岗岩 伸展构造 内蒙古 

分 类 号：P588.12[天文地球—岩石学] P597[天文地球—地质学]