| 内蒙古干劲山地区二长花岗岩年代学及地球化学特征研究 |
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| 作者姓名： | 高鉴 马刚 邹运鑫 任超军 余双双 |
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| 作者单位： | 内蒙古地质矿产勘查院,呼和浩特 010010 |
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| 基金项目： | 中国地质调查局“内蒙古 1∶5 万红梁子、沙多山、红旗山、蓬勃山幅区域地质矿产调查(编号: 1212011220461)”项目资助 |
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| 摘 要： | 通过对内蒙古额济纳旗干劲山地区二长花岗岩的锆石U-Pb年代学、岩石地球化学特征研究,探讨了其侵入年代与构造背景。二长花岗岩的LA-ICP-MS锆石U- Pb加权平均年龄为(276.63±0.84)Ma, 属早二叠世。岩石地球化学研究显示二长花岗岩A/CNK值为0.97~1.15,里特曼指数(σ值)为1.64~1.96,属准铝质—过铝质钙碱性系列花岗岩。岩石富集Rb、Ba、Sr等大离子亲石元素和Th、U、Zr等高场强元素。稀土元素特征为轻稀土富集, 轻、重稀土分异不明显, 轻稀土发生了较明显的分馏作用,铕负异常较明显。岩体为同造山“I”型花岗岩,其构造背景为陆缘弧,是干劲山地区晚华力西期造山运动的产物,红石山—路井裂谷带在晚古生代的拼合时间被限定到早二叠世晚期之后。
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| 关 键 词： | 二长花岗岩 锆石U-Pb年龄 地球化学特征 干劲山地区 内蒙古 |
| 收稿时间： | 2016-04-08 |
Geochronology and geochemical characteristic of monzonitic granite in Ganjin Mountain of Inner Mongolia |
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| Authors: | GAO Jian MA Gang ZOU Yunxin REN Chaojun YU Shuangshuang |
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| Institution: | Geology and Mineral Exploration Institute of Inner Mongolia, Hohhot 010010, China |
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| Abstract: | By investigating the geochronology and petrogeochemistry of monzonitic granite in Ganjin Mountain, Ejinaqi, Inner Mongolia, the intruding age and tectonic background are discussed. The zircon U-Pb weighted average age is considered to be (276.63±0.84) Ma by using LA-ICP-MS method, constraining its formation age to be Early Permian. Lithological and geochemical characteristics indicate that the monzonitic granite belongs to subaluminous-peraluminous and calc-alkaline series, with A/CNK ratios of 0.97-1.15 and σ values of 1.64-1.96. The monzonitic granite is rich in large ion lithophyte elements (LILE, e.g., Rb, Ba, Sr), high field strength elements (HFSE, e.g., Th, U, Zr), and LREE with negative euanomolies on the chondrite-normalized diagram, and its LREEs and HREEs are not obviously differentiated. They share affinities with syn-orogenic I-type granites, indicating they formed in a continental arc setting. It is suggested that the monzonitic granite was generated during late Hercynian movement in Ganjin area. The time that terranes on both sides of the Hongshishan-Lujing rifting belt converged was limited to Early Permian. |
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| Keywords: | monzonitic granite zircon U-Pb age geochemistry Ganjin Mountain Inner Mongolia |
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