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

• Petrology • Previous Articles     Next Articles

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

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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