延边地区明月沟组安山岩的形成时代与岩石成因:锆石U-Pb年代学、地球化学及Hf同位素证据  

Geochronology and petrogenesis of andesite rocks from Mingyuegou Formation in Yanbian area:evidenced by zircon U-Pb dating,geochemistry and zircon Hf isotopes

作　　者：王晰[1,2] 薛昊日[1,3] 赵东升 WANG Xi;XUE Hao-ri;ZHAO Dong-sheng(College of Earth Sciences, Jilin University, Changchun 130061, China;Applied Technology College, Jilin University, Changchun 130012, China;Institute of Geologic Survey of Jilin Province, Changchun 130061, China;Inner Mongolia Chifeng Geology and Mineral Resources Exploration Development Institute, Chifeng 024000,Inner Mongolia, China)

机构地区：[1]吉林大学地球科学学院,长春130061 [2]吉林大学应用技术学院,长春130012 [3]吉林省地质调查院,长春130061 [4]内蒙古赤峰地质矿产勘查开发院,内蒙古赤峰024000

出　　处：《世界地质》2016年第3期628-640,共13页World Geology

基　　金：国家自然科学基金青年科学基金项目(41402043);国家自然科学基金项目(41272094)联合资助

摘　　要：为确定延边地区明月沟组火山岩的形成时代、成因及构造背景,对明月沟组中的安山岩开展了岩石学、SIMS锆石U-Pb年代学、岩石地球化学及锆石Hf同位素特征研究。结果表明:明月沟组安山岩中的锆石为岩浆成因锆石。代表安山岩形成时代的两件样品中锆石的^(206)Pb/^(238)U加权平均年龄分别为(111±4)Ma(n=6,MSWD=3.2)和(113±3)Ma(n=6,MSWD=1.4),属早白垩世晚期。岩石地球化学特征上,明月沟组安山岩相对富钠,属高钾钙碱性系列,具有明显富集大离子亲石元素(K、Ba)和轻稀土元素,亏损重稀土元素和Ta、Nb等高场强元素的特征,结合其Hf同位素组成特征,暗示明月沟组安山岩的源岩应为受俯冲板片流体成份参与的亏损地幔。结合区域构造演化背景,明月沟组安山岩的形成应与早白垩世古太平洋板块向欧亚大陆板块的斜向俯冲作用相关。In order to determine the geochronology, petrogenesis and tectonic background of Mingyuegou Formation volcanic rocks in Yanbian area, the research of petrology, SIMS zircon U-Pb geochronology, geochemistry and zircon Hf isotopic have been taken. The results show that the zircons from the andesite rocks are magma genesis zircons, and the zircon 206Pb/238U dating were (111 ±4) Ma (Ti = 6 , MSWD =3. 2) and (113 ±3) Ma ( ti = 6,MSWD = 1 .4 ), belonging to the later Early Cretaceous. The geochemical data show that the andesite rocks belong to high-k calc-alkaline series, enriched in LILE ( K, Ba) and LREE, relatively depleted in HREE and HFSE ( such as Ta, Nb). Combined with Hf isotopes, it is showed the primary magmas of the andesite rocks of the Mingyuegou Formation were from the depleted mantle affected by subducted slab fluids. Combined with the research of regional tectonics, the formation of andesite rocks may be closely related to the subduction of Paleo -Pacific plate towards Eursia a plate.

关 键 词：明月沟组 安山岩 锆石U-Pb年龄 地球化学 HF同位素 

分 类 号：P595[天文地球—地球化学] P597[天文地球—地质学]