大兴安岭北段霍洛台地区石英闪长岩锆石U-Pb定年和Hf同位素特征  

Zircon U-Pb dating and Hf isotope characteristics of the quartz diorite in the Huoluotai area,northern segment of the Great Xing'an Range

作　　者：马双成 李焕纪 孙永刚 李晓林 陶善夫 靳皇玉 李斌[2] MA Shuangcheng;LI Huanji;SUN Yonggang;LI Xiaolin;TAO Shanfu;JIN Huangyu;LI Bin(School of Resources and Civil Engineering,Suzhou University,Suzhou 234000,Anhui,China;Institute of Geological Survey of Jilin Province,Changchun 130102,Jilin,China)

机构地区：[1]宿州学院资源与土木工程学院,安徽宿州234000 [2]吉林省地质调查院,吉林长春130102

出　　处：《吉林地质》2024年第4期1-7,15,共8页Jilin Geology

基　　金：宿州学院资助2024年国家级大学生创新创业训练计划项目(项目名称:华北板块北缘东段吉中地区中生代构造演化,项目编号:202410379063);2024年度安徽省教育厅高校自然科学重点科研项目(2024AH051826);宿州学院2022年博士科研启动基金项目(2022BSK009);宿州学院2023年博士后科研启动基金项目(2023BSH001)。

摘　　要：对位于大兴安岭北段霍洛台地区的石英闪长岩样品进行锆石U-Pb定年和Hf同位素特征研究,综合分析讨论霍洛台石英闪长岩的形成时代和岩浆源区,以提高东北大兴安岭地区中生代中性侵入岩的研究程度。结果显示,霍洛台石英闪长岩中锆石形态多呈柱状,岩浆振荡环带发育,具典型岩浆锆石特征。U-Pb定年所获得的结果表明,^(206)Pb/^(238)U加权平均值为(170.7±1.3)Ma(MSWD=0.55,n=14),代表石英闪长岩的形成年龄属于中侏罗世;1粒锆石的^(206)Pb/^(238)U年龄为(457.8±7.9)Ma,代表石英闪长岩上侵时所捕获的早期形成的锆石。霍洛台石英闪长岩锆石Hf同位素结果显示,锆石εHf(t)值为2.25~4.30,二阶段模式年龄(T_(DM2))为1074~943 Ma。结合前人研究结果,本文认为霍洛台地区至少存在2个岩浆侵入期次,依次为早-中侏罗世和晚侏罗世-早白垩世。霍洛台地区石英闪长岩样品锆石Hf同位素特征和捕获锆石表明,石英闪长岩的岩浆源区可能为新生地壳,且在向地表上升的过程中,可能经历了地壳物质的混染。In order to improve the research degree of Mesozoic intermediate intrusive rocks in the Great Xing'an Range in Northeast China,this paper conducts a study on zircon U-Pb dating and Hf isotopic characteristics of quartz diorite samples from the Huoluotai area in the northern segment of the Great Xing'an Range,and discusses the formation age and magma source of Huoluotai quartz diorite through comprehensive analysis.The results show that zircons in the Huoluotai quartz diorite are mostly columnar,with well-developed magmatic oscillatory zoning,showing typical magmatic zircon characteristics.The U-Pb dating results indicate a weighted average^(206)Pb/^(238)U age of 170.7±1.3 Ma(MSWD=0.55,n=14),indicating that the quartz diorite formed in the Middle Jurassic.One zircon grain yielded a^(206)Pb/^(238)U age of 457.8±7.9 Ma,corresponding to an earlier zircon captured during the upward intrusion of the quartz diorite.The Hf isotopic analysis of the zircons from the Huoluotai quartz diorite showsεHf(t)values ranging from 2.25-4.30,with two-stage model ages(T_(DM2))ranging from 1074-943 Ma.Combined with previous research findings,this study suggests that at least two magmatic intrusion events occurred in the Huoluotai area:the Early-Middle Jurassic and the Late Jurassic-Early Cretaceous.The Hf isotopic characteristics and the captured zircon in the Huoluotai quartz diorite indicate that its magma source may have originated from juvenile crust and possibly underwent crustal contamination during its ascent to the surface.

关 键 词：大兴安岭北段 石英闪长岩 锆石U-PB定年 HF同位素 岩浆源区 

分 类 号：P597[天文地球—地球化学]