赵广明, 李钢柱. 内蒙古乌拉特中旗扎嘎乌苏岩体LA-ICP-MS锆石U-Pb年龄、地球化学特征及其地质意义[J]. 地质通报, 2019, 38(2-3): 349-359.
    引用本文: 赵广明, 李钢柱. 内蒙古乌拉特中旗扎嘎乌苏岩体LA-ICP-MS锆石U-Pb年龄、地球化学特征及其地质意义[J]. 地质通报, 2019, 38(2-3): 349-359.
    ZHAO Guangming, LI Gangzhu. LA-ICP-MS zircon U-Pb age and geochemistry of the Zhagawusu intrusive body in Urad Middle Banner of Inner Mongolia and its geological significance[J]. Geological Bulletin of China, 2019, 38(2-3): 349-359.
    Citation: ZHAO Guangming, LI Gangzhu. LA-ICP-MS zircon U-Pb age and geochemistry of the Zhagawusu intrusive body in Urad Middle Banner of Inner Mongolia and its geological significance[J]. Geological Bulletin of China, 2019, 38(2-3): 349-359.

    内蒙古乌拉特中旗扎嘎乌苏岩体LA-ICP-MS锆石U-Pb年龄、地球化学特征及其地质意义

    LA-ICP-MS zircon U-Pb age and geochemistry of the Zhagawusu intrusive body in Urad Middle Banner of Inner Mongolia and its geological significance

    • 摘要: 内蒙古乌拉特中旗中蒙边境地区的扎嘎乌苏岩体主要由闪长岩、石英闪长岩、花岗闪长岩和黑云母二长花岗岩组成,岩体及围岩普遍发育面理南倾的糜棱岩带。通过LA-ICP-MS锆石U-Pb测年,获得扎嘎乌苏岩体中黑云母二长花岗岩的结晶年龄为450.3±3.7Ma(MSWD=2.8),表明扎嘎乌苏岩体的形成时代为晚奥陶世。扎嘎乌苏岩体中不同类型岩石全岩微量和稀土元素组成总体相似,均呈现轻稀土元素相对于重稀土元素强烈富集,大离子亲石元素Ba、Sr等富集,高场强元素Nb、Ta、Ti相对亏损,高Sr,低Y、Yb,高Sr/Y、La/Yb值等特征,具有埃达克岩和岛弧岩浆岩的地球化学特征。这些新的年代学和岩石地球化学数据,为索伦山地区晚奥陶世古亚洲洋俯冲消减提供了可靠的证据。

       

      Abstract: The Zhagawusu intrusive body is located close to the border between China and Mongolia and lies in northern Urad Middle Banner, Inner Mongolia. It mainly consists of diorite, quartz diorite, granodiorite and biotite monzonitic granite. The U-Pb age of zircons from the biotite monzonitic granite determined by LA-ICP-MS is 450.3±3.7Ma(MSWD=2.8).The rock samples are all characterized by strong enrichment of light rare-earth elements relative to heavy rare-earth elements, depletion of some high field strength elements such as Nb, Ta and Ti, high Sr, low Y and Yb content, and high Sr/Y and La/Yb ratios. The features indicate that the Zhagawusu intrusive body has a transitional normal arc/adakite geochemical affinity. The new age and geochemical data from the Zhagawusu intrusive body provide convincing evidence for Late Ordovician subduction of the Paleo-Asian Ocean in this region.

       

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