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现代地质 ›› 2020, Vol. 34 ›› Issue (03): 466-482.DOI: 10.19657/j.geoscience.1000-8527.2020.023

• 岩石学 • 上一篇    下一篇

大兴安岭南段晚中生代侵入岩时空分布及主脊与东坡岩体特征对比

王迪1,2(), 赵国春1, 苏尚国1(), 李宏星3   

  1. 1.中国地质大学(北京) 地球科学与资源学院,北京 100083
    2.中国石化 新星(北京)新能源研究院有限公司,北京 100083
    3.核工业北京化工冶金研究院,北京 101149
  • 收稿日期:2019-03-23 修回日期:2020-01-13 出版日期:2020-07-04 发布日期:2020-07-05
  • 通讯作者: 苏尚国
  • 作者简介:苏尚国,男,教授,博士生导师,1965年出生,矿物学、岩石学、矿床学专业,主要从事岩浆作用与岩浆矿床方面的研究。Email: susg@cugb.edu.cn
    王 迪,女,博士研究生,1990年出生,矿物学、岩石学、矿床学专业,主要从事岩浆作用与岩浆矿床方面的教学与研究。Email:wangd7707. xxsy@sinopec.com
  • 基金资助:
    中国地质调查局项目“华北地区古生代、中生代构造岩浆热事件性质及资源效应综合研究”(1212011121072)

Spatial-temporal Distribution of Late Mesozoic Intrusive Rocks in South Daxing’anling Mountains and the Characteristic Contrast of Rocks in the Mid Ridge and the East Slope

WANG Di1,2(), ZHAO Guochun1, SU Shangguo1(), LI Hongxing3   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences,Beijing 100083,China
    2. New Energy Research Institute, SINOPEC Star Petroleum Co.,Ltd, Beijing 100083,China
    3. Beijing Research Institute of Chemical Engineering and Metallurgy, Beijing 101149,China
  • Received:2019-03-23 Revised:2020-01-13 Online:2020-07-04 Published:2020-07-05
  • Contact: SU Shangguo

摘要:

通过岩相学、地球化学、锆石U-Pb年代学对位于大兴安岭主脊上的马勒根坝岩体、朝阳沟岩体和大兴安岭东坡区域的野猪沟岩体、布敦化岩体的4个不同花岗岩岩体的岩石类型、主量和微量元素特征、年代学及构造背景进行对比分析,讨论了研究区在晚侏罗世—早白垩世的岩浆活动及地质背景。LA-ICP-MS锆石U-Pb年龄显示:主脊朝阳沟岩体和东坡布敦化岩体年龄分别为(154±1) Ma和(154.1±1.6) Ma,属于晚侏罗世岩体,主脊马勒根坝岩体和东坡野猪沟岩体年龄分别为(144.62±0.74) Ma和(140.2±2.7) Ma,属于早白垩世岩体。岩相学和地球化学特征显示:主脊岩体为高钾钙碱性-准铝质-过铝质花岗岩岩体,东坡岩体为钙碱性-高钾钙碱性-准铝质-弱过铝质TTG型岩体;主脊比东坡岩体更加亏损Ba、Nb、Sr、P、Ti、Eu元素,为高分异I型花岗岩,东坡岩体为正常的I型花岗岩。结合区域地质资料分析,认为在晚侏罗世—早白垩世伊泽奈崎板块NNW向俯冲和蒙古—鄂霍次克洋闭合共同作用于大兴安岭南段地区,在大兴安岭主脊形成断裂带,导致幔源岩浆上涌底侵下地壳而形成沿断裂带分布的花岗岩体;主脊处于碰撞向伸展环境过渡的时期,东坡区域此时应处于俯冲时期。

关键词: 大兴安岭, 地球化学, 锆石U-Pb年代学, 蒙古—鄂霍次克洋

Abstract:

This work studied the petrology, major and trace element geochemistry, and zircon U-Pb ages of four different granites in the Daxing’anling Mountains (DM), i.e., Malegenba and Chaoyanggou in the DM main ridge,and the Yezhugou and Budunhua in the DM eastern slope,in order to better constrain the magmatic background of the Late Mesozoic DM. LA-ICP-MS zircon U-Pb dating of the Chaoyanggou and Budunhua granites yielded Late Jurassic ages of (154±1) Ma and (154.1±1.6) Ma, respectively, whereas the Malegenba and Yezhugou granites yielded Early Cretaceous ages of (144.62±0.74) Ma and (140.2±2.7) Ma, respectively. According to the petrographic and geochemical characteristics, the DM main-ridge granites are high-K calc-alkaline, metaluminous, and highly-fractionated I-type;whereas those in the DM eastern slope are cal-calkaline to high-K calc-alkaline and metaluminous to peraluminous TTG I-type. The DM main-ridge granites are more depleted in Ba, Nb, Sr, P, Ti, and Eu than their DM eastern-slope counterparts. Combined with the regional geology, the southern DM region was probably co-influenced by the rapid NNW-directed oblique subduction of the Izanagi plate and the Mongolia-Okhotsk Ocean closure during the Late Jurassic to Early Cretaceous. The DM main-ridge granites were probably formed by the partial melting of the lower crust underplated by and mixed with mantle-derived magma, and the granitic magmas were intruded along the fault zones in the DM main ridge. Meanwhile, the DM eastern-slope granites were formed by the collision-related crustal thickening at that time.

Key words: Daxing’anling Mountains, geochemistry, zircon U-Pb dating, Mongolia-Okhotsk Ocean

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