地学前缘 ›› 2018, Vol. 25 ›› Issue (3): 230-239.DOI: 10.13745/j.esf.yx.2017-3-53

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内蒙古索伦山地区哈尔博格托尔TTG岩锆石年代学、岩石地球化学及大地构造意义

薛建平，刘美玉，李钢柱，赵广明，吴春娇，李成元，刘永新，梁月升，连琛芹   

  1. 1. 中国地质大学(北京) 地球科学与资源学院, 北京 100083
    2. 武警黄金第二支队, 内蒙古 呼和浩特 010010
  • 收稿日期:2017-07-12 修回日期:2017-11-20 出版日期:2018-05-15 发布日期:2018-05-15
  • 作者简介:薛建平(1974—)，男，博士，工程师，矿物学、岩石学、矿床学专业。E-mail:1438319972@qq.com
  • 基金资助:
    中国地质调查局区域地质矿产调查项目(12120113071800)

Zircon geochronology and geochemistry of the Haer Bogetuoer TTG rock, Solonker zone, Inner Mongolia and their tectonic implications.

XUE Jianping,LIU Meiyu,LI Gangzhu,ZHAO Guangming,WU Chunjiao,LI Chengyuan,LIU Yongxin，LIANG Yuesheng，LIAN Chenqin   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing 100083, China
    2. No.2 Gold Geological Party of CAPF, Huhhot 010010, China
  • Received:2017-07-12 Revised:2017-11-20 Online:2018-05-15 Published:2018-05-15

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摘要： 内蒙古索伦山地区是中亚造山带构造演化的关键区域，其中关于古亚洲洋的闭合时限以及西伯利亚板块和华北板块的拼贴时空关系一直存在争议。出露于内蒙古索伦山地区哈尔博格托尔的中酸性侵入岩，其深入研究对探讨古亚洲洋演化具有重要意义。文中对内蒙古索伦山地区哈尔博格托尔TTG岩进行了系统的岩石学、年代学及地球化学研究。获得哈尔博格托尔TTG岩的LAICPMS锆石UPb年龄为(266.7±3.7) Ma，表明该侵入岩形成于中二叠世。地球化学主量元素分析表明，索伦山地区哈尔博格托尔TTG岩的岩石系列主要为含钠较高的钙碱性准铝质系列。其稀土元素总量较低，呈现轻稀土元素(LREEs)相对于重稀土元素(HREEs)弱富集的特征，Eu异常不明显；微量元素呈现Rb、Ba、Th、U等大离子亲石元素富集，Nb、Ta、Ti等高场强元素强烈亏损的特征，与典型的岛弧岩浆岩类似。结合索伦山TTG岩体地质特征和区域地质背景，综合年代学和地球化学特征分析，笔者认为索伦山地区哈尔博格托尔TTG岩体形成于岛弧环境，即中二叠世期间古亚洲洋壳向华北板块还存在俯冲作用，因而古亚洲洋至少应在中二叠世以后才闭合。内蒙古索伦山地区哈尔博格托尔TTG岩是洋壳俯冲的岩石学记录，为索伦山缝合带及古亚洲洋构造域演化提供了新的基础地质资料。

关键词: U-Pb年龄, 锆石, LA-ICP-MS, TTG岩, 岛弧, 索伦山, 古亚洲洋

Abstract: The Solonker zone, Inner Mongolia is a key area in the evolution of the Central Asia Orogenic Belt (CAOB). It lies at the center of an ongoing debate on the PaleoAsian Ocean closure time and temporospatial relationship between the North China and Siberian Plates. It is therefore essential to study indepth the intermediaacid intrusive rock of this region. In this work, we carried out a systematic investigation on the petrology, chronology and geochemistry of the Haer Bogetuoer TTG rock. LAICPMS zircon UPb age dating 266.7±3.7 Ma indicated the TTG rock from Solonker was emplaced during the middle Permian. Geochemical analysis of major elements showed that the lithological series belonged to the highsodium calcalkali and metaluminous rock series. The overall content of rareearth elements (REEs) was low in the TTG rock, with light REEs slightly enriched without apparent Eu anomaly. Rock samples were enriched in large ionic lithophile elements including Rb, Ba, Th and U, and extremely depleted in high field strength elements such as Nb, Ta and Ti. These geochemical characteristics are similar to that of typical magmatite in an island arc setting. Integrating geological, tectonic, chronologic and geochemical characteristics of the TTG rock, we conclude that the TTG rock complex from Solonker formed in an island arc setting, and the subduction of the PaleoAsian Ocean plate beneath the North China plate continued during the middle Permain, implying the PaleoAsian Ocean did not close until the middle Permain. The Haer Bogetuoer TTG from the Solonker zone, Inner Mongolia serves as petrological record of ocean crust underthrusting. Our study provides new geological insight into the evolution of the Solonker suture zone and PaleoAsian Ocean tectonic domain.

Key words:  U-Pb age, zircon, LA-ICP-MS, TTG rock, island arc, Solonker, PaleoAsian Ocean

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