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现代地质 ›› 2022, Vol. 36 ›› Issue (01): 307-320.DOI: 10.19657/j.geoscience.1000-8527.2021.068

• 岩石学 • 上一篇    下一篇

内蒙古白乃庙铜金矿床侵入岩年代学及其地质意义

吕钊1(), 王建平1(), 王继春2, 许展2, 袁硕浦1   

  1. 1. 中国地质大学(北京) 地球科学与资源学院,北京 100083
    2. 内蒙古自治区地质调查院,内蒙古 呼和浩特 010020
  • 收稿日期:2021-03-11 修回日期:2021-11-10 出版日期:2022-02-10 发布日期:2022-03-08
  • 通讯作者: 王建平
  • 作者简介:王建平,男,教授,1972年出生,矿物学、岩石学、矿床学专业,主要从事矿床学的教学与科研工作。Email: jpwang@cugb.edu.cn
    吕 钊,男,硕士研究生,1996年出生,矿物学、岩石学、矿床学专业,主要从事矿床学与矿床地球化学研究。Email: lvzhao01@qq.com
  • 基金资助:
    内蒙古自治区地质勘查基金项目“内蒙古自治区中部满都拉-白乃庙一带铜金多金属矿成矿规律与找矿预测”(2018-01-YS01)

Geochronology and Geological Significance of Intrusive Rocks in the Bainaimiao Cu-Au Deposit, Inner Mongolia

LÜ Zhao1(), WANG Jianping1(), WANG Jichun2, XU Zhan2, YUAN Shuopu1   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China
    2. Geological Survey Institute of Inner Mongolia, Hohhot, Inner Mongolia 010020, China
  • Received:2021-03-11 Revised:2021-11-10 Online:2022-02-10 Published:2022-03-08
  • Contact: WANG Jianping

摘要:

内蒙古白乃庙铜金矿床位于华北板块北缘中段陆缘增生带,区内侵入岩发育,主要岩性有花岗闪长岩、白云母花岗岩、石英闪长岩,对其中5件样品采用LA-MC-ICP-MS锆石U-Pb方法测年,获得花岗闪长岩加权平均年龄(443.2±1.7) Ma、(447.6±1.8) Ma,白云母花岗岩加权平均年龄(429.1±2.7) Ma、(431.6±4.2) Ma,石英闪长岩加权平均年龄(424.5±2.0) Ma。结合矿床地质特征分析认为白乃庙铜矿化时代为432~447 Ma,为晚奥陶世—早志留世,与花岗闪长岩侵位有关;白乃庙金矿床形成于430 Ma左右,与白云母花岗岩侵位带来的丰富热液有关。在早古生代古亚洲洋板块向华北板块俯冲的背景下,铜成矿以挤压环境为主,形成斑岩型铜矿化,而金成矿作用发生在相对张性构造环境,形成浅成低温热液型金矿化,在白乃庙岛弧的火山-岩浆作用下共同构成了一个斑岩-浅成低温热液成矿系统。

关键词: 白乃庙铜金矿床, 侵入岩, 锆石U-Pb定年, 内蒙古

Abstract:

The Bainaimiao Cu-Au deposit in Inner Mongolia is located in the continental marginal accretionary zone in the northern margin (middle section) of the North China Craton. Intrusive rocks are developed at Bainaimiao, with major lithologies including granodiorite, muscovite granite, and quartz diorite. LA-MC-ICP-MS zircon U-Pb dating indicate that the granodiorite was emplaced at (443.2±1.7) Ma and (447.6±1.8)Ma, the muscovite granite was formed at (429.1±2.7) Ma and (431.6±4.2) Ma, and the quartz diorite was formed at (424.5±2.0) Ma. Combined with the ore deposit geological characteristics, we considered that the Bainaimiao Cu mineralization occurred in the Late Ordovician-Early Silurian (432-447 Ma), related to the granodiorite emplacement. The Bainaimiao gold deposit was formed at about 430 Ma, which is related to the hydrothermal fluid enrichment brought by the muscovite granite emplacement. Under the Early Paleozoic subduction tectonics of the Paleo-Asian Ocean beneath the North China Craton, the porphyry Cu mineralization was dominated by the compression tectonics, whilst the epithermal Au mineralization occurred in a relatively extensional setting. Under the volcanic rock-magma process of the Bainaimiao island arc, the Bainaimiao Cu and Au mineralization constitutes an integral porphyry-epithermal mineral system.

Key words: Bainaimiao Cu-Au deposit, intrusive rock, zircon U-Pb dating, Inner Mongolia

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