地学前缘 ›› 2020, Vol. 27 ›› Issue (4): 232-243.DOI: 10.13745/j.esf.sf.2020.4.12

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藏东芒康县巴达铜金矿床地质特征及找矿方向研究

杨富成,李文昌,祝向平,江小均,刘俊,廖忠礼,刘鸿飞,杨后斌,李勇   

  1. 1. 中国地质大学(北京) 地球科学与资源学院, 北京 100083
    2. 成都理工大学 地球科学学院, 四川 成都 610059
    3. 中国地质调查局 成都地质调查中心, 四川 成都 610081
    4. 昆明理工大学 国土资源工程学院, 云南 昆明 650093
    5. 西藏自治区地质调查院, 西藏 拉萨 850000
  • 收稿日期:2020-01-05 修回日期:2020-03-27 出版日期:2020-07-25 发布日期:2020-07-25
  • 通讯作者: 李文昌(1962—),男,教授,博士生导师,主要从事地质矿产勘查与矿床研究工作。
  • 作者简介:杨富成(1994—),男,博士研究生,矿物学、岩石学、矿床学专业。E-mail:446369580@qq.com
  • 基金资助:

    国家自然科学基金项目(41272091);云南省科学技术杰出贡献奖项目(2017001);中国地质调查局地质调查项目(DD20160016,DD20179604)

Geological characteristics and prospecting of the Bada Cu-Au deposit in Mangkang County, East Tibet

YANG Fucheng,LI Wenchang,ZHU Xiangping,JIANG Xiaojun,LIU Jun,LIAO Zhongli,LIU Hongfei,YANG Houbin,LI Yong   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing 100083, China
    2. School of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China
    3. Chengdu Geological Survey Center, China Geological Survey, Chengdu 610081, China
    4. School of Land and Resources Engineering, Kunming University of Science and Technology, Kunming 650093, China
    5. Tibet Institute of Geological Survey, Lhasa 850000, China
  • Received:2020-01-05 Revised:2020-03-27 Online:2020-07-25 Published:2020-07-25

摘要:

巴达铜金矿位于藏东富碱斑岩带南段,是藏东地区近年来新发现的大型铜金矿。虽然对巴达铜金矿开展了大量勘查工作,但对该矿床的成因尚未取得共识。本文基于详细的野外调研、岩心与坑道编录及系统的镜下鉴定,对巴达铜金矿床地质特征进行研究。巴达矿床主要产于石英二长斑岩中,局部产于斑岩和砂岩地层的接触带内。矿床发育的围岩蚀变主要为青磐岩化、钾化、绢英岩化,高岭土化、蛋白石化、蒙脱石化次之,蚀变分带从内向外依次为钾硅酸盐化带、绢英岩化带、青磐岩化带、高岭土化带,铜金矿体主要赋存于钾硅酸盐化和绢英岩化带内,铜矿化主要以黄铜矿形式产出,金矿化主要以银金矿形式产于白云石±石英+细粒黄铁矿±黄铜矿脉中,铜矿化与金矿化呈正相关,矿体的产出受北西向逆冲断层的控制。与典型斑岩和浅成低温热液矿床不同,巴达铜金矿化主要产于白云石±石英+黄铁矿脉中;矿床内既发育碳酸盐、伊利石、绢云母和黄铁矿、黄铜矿、方铅矿、黝铜矿、低FeS闪锌矿等一套中硫型浅成低温热液矿床的蚀变矿物组合,又发育符合碱性斑岩系统的特征矿物赤铁矿。基于以上特征判断,巴达铜金矿矿床成因类型应为与富碱斑岩有关的浅成低温热液矿床,巴达铜金矿矿床成因的厘定,为下一步找矿提供了理论指导。

关键词: 巴达铜金矿床, 浅成低温热液矿床, 中硫型, 藏东富碱斑岩成矿带, 描述模型

Abstract:

The Bada Cu-Au deposit, a newly discovered large Cu-Au deposit, is located in the southern part of the alkali-rich porphyry belt in East Tibet. The metallogenic features of the Bata Cu-Au deposit are not yet clear. Based on detailed field observation, geological logging and systematic microscopic examination, we studied the geological characteristics of the Bada Cu-Au deposit. The deposit developed within the quartz monzonite porphyry intrusion while the surrounding sandstones are controlled by a NW-striking thrust fault. We identified the alteration types, including potassic, phyllic and propylitic alterations, and delineated the alteration zones. We also found small quantity of localized secondary minerals such as kaolinite, opal and montmorillonite. The Cu-Au orebody mainly occurs in the potassic and phyllic alteration zone, showing positive correlation between Cu and Au mineralization. Copper mineralization mainly produces chalcopyrite, while gold occurs primarily as fine Ag-Au grains in dolomite±quartz+pyrite±chalcopyrite vein. Both alteration and mineralization are centralized along the NW-striking thrust fault. Unlike typical porphyry and epithermal deposit, mineralization in the Bada Cu-Au deposit mainly occurs in dolomite±quartz+pyrite vein, resembling the low temperature alteration assemblage. The alteration and mineralization associated minerals, such as carbonate, illite, sericite, galena, pyrite, chalcopyrite and tetrahedrite, are found in the ore district, consistent with intermediate sulfidation epithermal deposits. Moreover, hematite is ubiquitous, indicating an alkaline porphyry system. Thus, we conclude that the Bada Cu-Au deposit belongs to alkali-rich porphyry related epithermal deposit. Its metallogenic mechanism can be used to guide the next prospecting exploration.

Key words: Bada Cu-Au deposit, epithermal deposit, intermediate sulfidation, alkali-rich porphyry belt in East Tibet, description model

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