地学前缘 ›› 2018, Vol. 25 ›› Issue (1): 108-124.DOI: 10.13745/j.esf.yx.2017-5-21

• 构造控矿与低温成矿作用 • 上一篇    下一篇

云南因民铜矿床构造沉积环境及成矿机制研究

代鸿章，刘家军，朱文兵   

  1. 1. 中国地质科学院 矿产资源研究所, 北京 100037
    2. 中国地质大学 地质过程与矿产资源国家重点实验室, 北京 100083
  • 收稿日期:2016-12-01 修回日期:2017-02-24 出版日期:2018-01-15 发布日期:2018-01-15
  • 作者简介:代鸿章（1985—），男，博士，矿物学、岩石学、矿床学专业。E-mail：303829636@qq.com
  • 基金资助:
    国家重点基础研究发展计划“973”项目（2014CB440903）

Studies on tectonic setting, sedimentary environment and mineralization mechanism of the Yinmin copper deposit in Yunnan Province

DAI Hongzhang,LIU Jiajun,ZHU Wenbing   

  1. 1. Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
    2. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China
  • Received:2016-12-01 Revised:2017-02-24 Online:2018-01-15 Published:2018-01-15

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摘要： 因民铜矿床是云南省东川铜矿田中一个重要的矿床，发育有两种矿化类型，分别为赋存于因民组中的稀矿山式铜铁矿体以及赋存于落雪组地层中的东川式铜矿体。文中采用主、微量元素地球化学方法并结合相关热力学计算，探讨含矿岩系因民组及落雪组的岩石特征、沉积环境、构造背景及其铁、铜迁移机制和富集机理。结果表明，因民组及落雪组中以白云岩、硅质白云岩为主，并含少量白云质砂岩，综合100(Fe2O3/SiO2)100(Al2O3/SiO2)、Fe2O3/TiO2Al2O3/(Al2O3+Fe2O3)、La-Th-Sc及Th-Co-Zr/10关系图解，指示因民组及落雪组具有大陆边缘区的沉积特点。V/Cr、V/(V+Ni)及Ce/La氧化还原环境判别图显示，因民组及落雪组整体形成于贫氧过渡状态下的深水半深水沉积环境。热力学计算表明，在流体迁移过程中，铁、铜主要以氯的络合物形式进行迁移，当成矿流体运移到表层与含硫碱性较还原性水体发生混合时，导致成矿体系温度、Eh和f(S2)降低，pH值升高，铜、铁络合物发生失稳，先后生成磁铁矿、赤铁矿等氧化物以及黄铁矿、黄铜矿、斑铜矿、辉铜矿等硫化物，在因民组及落雪组中分别形成稀矿山式铜铁矿体和东川式铜矿体。

关键词: 构造背景, 沉积环境, 成矿机制, 因民铜矿床

Abstract: The Yinmin deposit is an important deposit in the Dongchuan copper ore field in Yunnan Province. It has two mineralization types, one is the FeCu deposit of Xikuangshan type from the Yinmin Formation of the Kunyang Group, the other is the Cu deposit of Dongchuan type from the Luoxue Formation. In this paper, major and trace elemental analyses were combined with thermodynamic calculation to reveal rock characteristics, tectonic setting, sedimentary environment, and mechanism of migration and accumulation of iron and copper. Results show that the Yinmin and Luoxue formations mainly consist of dolomites and siliceous dolomites with dolomitic sandstone as a minor component. Comprehensive analyses of various diagrams, such as 100(Fe2O3/SiO2)100(Al2O3/SiO2), Fe2O3/TiO2Al2O3/(Al2O3+Fe2O3), LaThSc and ThCoZr/10 graphs, indicate that the contents of carbonate samples from the two formations were consistent with an active continental margin sedimentary system. Discrimination diagrams of redox environment, such as V/Cr, V/(V+Ni) and Ce/La, indicate that the Yinmin and Luoxue formations were deposited in a deep water to semideepwater transitional dysaerobic basin. Thermodynamic calculation results show that iron and copper transported mainly in the form of Cl complex. First, temperature, Eh and f(S2) decreased while pH increased in the oreforming system as oreforming fluid transported to the surface and mixed with the reduced water. Then instability occurred in the complexes of copper and iron. Finally, oxides including hematite and magnetite, sulfides including pyrite, chalcopyrite, bornite and chalcocite changed sequentially with changes in the physical and chemical environment, and formed the ferrocopper and copper ore bodies of the Xikuangshan and Dongchuan types, respectively.

Key words: tectonic setting, sedimentary environment, mineralization mechanism, Yinmin copper deposit

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