地学前缘 ›› 2024, Vol. 31 ›› Issue (3): 113-132.DOI: 10.13745/j.esf.sf.2023.6.17

• 金属成矿作用与成矿预测 • 上一篇    下一篇

滇西保山地块陡崖铁铜多金属矿床石榴子石年代学及其地球化学特征

李方兰1(), 刘学龙1,*(), 周云满2, 赵成峰2, 李守奎1, 王基元2, 陆波德1, 李庆锐2, 张卫文2, 王海2, 曹振梁1, 周杰虎1   

  1. 1.昆明理工大学 国土资源工程学院, 云南 昆明 650093
    2.云南黄金矿业集团股份有限公司, 云南 昆明 650299
  • 收稿日期:2023-04-12 修回日期:2023-05-20 出版日期:2024-05-25 发布日期:2024-05-25
  • 通信作者: *刘学龙(1983—),男,教授,博士生导师,主要从事区域成矿学、岩浆热液成矿作用和地质大数据的研究工作。E-mail: xuelongliu@foxmail.com
  • 作者简介:李方兰(1997—),女,硕士研究生,地球化学专业,主要从事岩石学、地球化学的研究工作。E-mail: 3462644230@qq.com
  • 基金资助:
    昆明理工大学“双一流”科技专项(202202AG050006-2);国家自然科学基金项目(42362010);云南黄金集团校企合作项目(KKF02021212097)

Geochronology and geochemical characteristics of the Douya iron-copper polymetallic deposit in the Baoshan block, western Yunnan

LI Fanglan1(), LIU Xuelong1,*(), ZHOU Yunman2, ZHAO Chengfeng2, LI Shoukui1, WANG Jiyuan2, LU Bode1, LI Qingrui2, ZHANG Weiwen2, WANG Hai2, CAO Zhenliang1, ZHOU Jiehu1   

  1. 1. Faculty of Land Resources Engineering, Kunming University of Science and Technology, Kunming 650093, China
    2. Yunnan Gold & Mining Group Co. Ltd., Kunming 650299, China
  • Received:2023-04-12 Revised:2023-05-20 Online:2024-05-25 Published:2024-05-25

摘要:

陡崖夕卡岩型铁铜多金属矿床位于保山—镇康铅锌多金属矿带北段。区内矿体产于寒武系上统核桃坪组和沙河厂组中,岩性主要为大理岩化灰岩和夹泥质灰岩。目前,矿区内尚未揭露中酸性岩体。为厘清该矿床的成矿时代、成矿的物理化学条件和成矿流体的性质,我们对该矿床的石榴子石开展了细致的岩相学工作、地球化学分析以及LA-SF-ICP-MS U-Pb定年测试。结合野外调查与岩相学工作,主量元素特征表明:保山陡崖矿床产出的石榴子石属于钙铝榴石-钙铁榴石固溶体系列,且该矿区的石榴子石可划分为两类(GrtⅠ和GrtⅡ)。微量元素特征表明:在陡崖矿床,随着温度、氧逸度的变化,流体体系的pH值经历了早期的中性—晚期的酸性的转变。通过应用石榴子石LA-SF-ICP-MS U-Pb定年方法,获得468~461 Ma的可靠年龄数据,表明滇西保山地块陡崖矿床成矿作用发生于中奥陶世。结合双脉地、清水河花岗岩与之相似的稀土配分曲线以及形成时代,推测该矿床可能与岩石圈地幔的拆沉作用有关,其源区主要为古老大陆地壳部分熔融,并有幔源物质的加入。

关键词: 陡崖铁铜多金属矿床, 石榴子石, LA-SF-ICP-MS U-Pb定年, 成矿时代, 流体

Abstract:

The Douya iron-copper polymetallic deposit is a skarn-type deposit located in the northern portion of the Baoshan-Zhenkang lead-zinc polymetallic ore belt. The orebodies are found in the Hetaoping Formation and Shahechang Formation of the Upper Cambrian system, characterized by marbled limestone intercalated with argillaceous limestone. No intermediate-acid rock bodies have been identified within the deposit. To elucidate the age of ore formation, physical and chemical conditions of ore formation, and properties of ore-forming fluids, comprehensive petrographic analysis, geochemical analysis, and LA-SF-ICP-MS U-Pb dating were conducted on garnets from the deposit. The major element characteristics of the garnets from the Douya deposit in the Baoshan block indicate that they belong to the grossular-andradite solid solution series and can be classified into two types: Grt I and Grt II. Variations in temperature and oxygen fugacity within the Douya deposit have influenced the trace element composition, indicating a transition in the pH of the fluid system from early neutrality to late acidity. LA-SF-ICP-MS U-Pb dating of the garnets yielded reliable age data of 468-461 Ma, suggesting that mineralization at the Douya deposit occurred during the Middle Ordovician. The similar rare earth distribution curve and formation age of Shuangmaidi and Qingshuihe granites suggest a potential connection between these deposits and the delamination of the lithospheric mantle. It is proposed that the main source of mineralization in the Douya deposit involves the partial melting of ancient continental crust in combination with materials derived from the mantle.

Key words: Douya iron-copper polymetallic deposit, garnet, LA-SF-ICP-MS U-Pb dating, metallogenic age, fluid

中图分类号: