| 新疆东天山哈尔里克奥陶纪的构造属性:来自火山岩LA ICP MS锆石U Pb年代学与地球化学的制约 |
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| 引用本文： | 李江涛,何学锋,刘亮,杨鹏涛,梁斌,苏画.新疆东天山哈尔里克奥陶纪的构造属性:来自火山岩LA ICP MS锆石U Pb年代学与地球化学的制约[J].现代地质,2017,31(3):460. |
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| 作者姓名： | 李江涛 何学锋 刘亮 杨鹏涛 梁斌 苏画 |
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| 作者单位： | 1四川省地质矿产勘查开发局 川西北地质队，四川 绵阳621010；2西南科技大学 环境与资源学院，四川 绵阳621010；
3贵州省地质调查院，贵州 贵阳550005；4中国科学院 地球化学研究所，贵州 贵阳550005 |
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| 基金项目： | 中国地质调查局项目“新疆天山哈密地区五幅1∶5万区域地质矿产调查”（12120113042400）；国家自然科学基金项目（41472310）。 |
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| 摘 要： | 新疆东天山哈尔里克造山带火山岩为一套酸性—基性岩(流纹岩、英安岩、安山岩、玄武岩)夹火山碎屑岩(凝灰岩)的岩石组合。流纹岩样品的LA ICP MS锆石U Pb定年结果显示，时代为中奥陶世大坪期((4688±91) Ma)，代表了该套火山岩的形成年龄。岩石地球化学分析结果显示，该套火山岩SiO2含量介于4912%～7824%，TiO2介于012%～100%，Al2O3介于1131%～2086%；铝饱和指数A/CNK值为080～131(均值为099)，里特曼指数σ值为019～386(均值为129)，Mg#值为887～4929(均值为3120)；富集大离子亲石元素(LILE)Ba、Rb以及轻稀土元素(∑LREE)La、Ce，亏损高场强元素(HFSE)Nb、Ta、Ti等。微量元素和稀土元素的相关图解与比值以及发育的捕获锆石反映了俯冲带岛弧钙碱性火山岩特征，且存在大陆地壳混染作用。综合区域地质资料分析，在早古生代期间(中奥陶世—早志留世)，哈尔里克造山带存在大面积的与岛弧演化有关的加里东期岩浆活动，此期间哈尔里克造山带的构造背景为洋壳俯冲有关的岛弧环境，其形成可能与东准噶尔南部克拉麦里洋向南俯冲作用有关。
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| 关 键 词： | 哈尔里克造山带 奥陶纪 岛弧火山岩 洋壳俯冲 LA ICP MS锆石U Pb定年 地球化学 |
Ordovician Tectonic Evolution of Harlik in Eastern Tianshan of Xinjiang: Constraints from LA-ICP-MS Zircon U-Pb Geochronology and Geochemistry of Volcanic Rocks |
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| LI Jiangtao,HE Xuefeng,LIU Liang,YANG Pengtao,LIANG Bin,SU Hua.Ordovician Tectonic Evolution of Harlik in Eastern Tianshan of Xinjiang: Constraints from LA-ICP-MS Zircon U-Pb Geochronology and Geochemistry of Volcanic Rocks[J].Geoscience——Journal of Graduate School,China University of Geosciences,2017,31(3):460. |
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| Authors: | LI Jiangtao HE Xuefeng LIU Liang YANG Pengtao LIANG Bin SU Hua |
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| Institution: | 1 Northwest Sichuan Geological Party，Sichuan Bureau of Geology and Mineral Resources,Mianyang,Sichuan621010，China；
2 School of Environment and Resource, Southwest University of Science and Technology，Mianyang,Sichuan621010，China；
3 Guizhou Academy of Geological Survey，Guiyang,Guizhou550005，China；
4 Institute of Geochemistry，Chinese Academy of Sciences，Guiyang, Guizhou550005，China |
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| Abstract: | The volcanic rocks in the Harlik orogenic belt of eastern Tianshan, Xinjiang are combined with a set of acid to basic rocks (rhyolite, dacite, andesite, basalt) intercalated with pyroclastic rocks(dacite tuff). U Pb dating of zircons from the samples of rhyolite by LA ICP MS yields weighed mean 206Pb/238U ages of (4688±91) Ma, which indicates that these volcanic rocks formed in Middle Ordovician. Geochemical analysis results show that the SiO2 contents are from 4912% to 7824%; TiO2 contents are from 012% to 100%; Al2O3 contents are from 1131% to 2086%; A/CNK ratios are from 080 to 131(with an average of 099); and Rittmann indexes (σ) are from 019 to 386(with an average of 129); Mg# values are from 887 to 4929(with an average of 3120). The rocks are rich in large ion lithophile elements(LILEs, eg, Rb, Ba) and light rare earth elements(LREEs,eg, La, Ce) and depleted in high field strength elements(HFSEs, eg, Nb, Ta, Ti). According to the relevant diagrams, the ratios about the trace elements and rare earth elements, and xenocrystic zircon, it indicates that there are typical arc volcanic rocks in supper subduction zone, and that the magma intruded the continental crust. Moreover, based on the analysis of regional geological data, during the Early Paleozoic (Middle Ordovician to Early Silurian), we can claim that there is a large island arc evolution related to the Caledonian tectonic magmatism, which tectonic background is the oceanic crust subduction of island arc environment, and its formation may be related to east Junggar Kelamaili ocean of the south subduction. |
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| Keywords: | Harlik orogenic belt Ordovician island arc volcanic rock subduction of the ocean crust LA ICP MS zircon U Pb dating geochemistry |
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