地学前缘 ›› 2019, Vol. 26 ›› Issue (5): 243-254.DOI: 10.13745/j.esf.sf.2019.9.20

• 岩浆过程与成矿 • 上一篇    下一篇

西秦岭太阳山斑岩铜钼矿床岩体氧逸度及成矿意义

勾宗洋，于皓丞，邱昆峰，吴鸣谦，周春生，朱锐，李俊，温依曈   

  1. 1. 中国地质大学(北京) 地球科学与资源学院; 地质过程与矿产资源国家重点实验室, 北京 100083
    2. 南京大学 内生金属矿床成矿机制国家重点实验室, 江苏 南京 210023
    3. 美国科罗拉多矿业学院 地质与地质工程系, 戈登 80401
    4. 招金矿业股份有限公司, 山东 招远 265400
  • 收稿日期:2019-05-31 修回日期:2019-07-25 出版日期:2019-09-28 发布日期:2019-09-28
  • 通讯作者: 邱昆峰(1986—)，男，博士，副教授，主要从事矿床学研究。
  • 作者简介:勾宗洋(1991—)，男，硕士，矿物学、岩石学、矿床学专业。E-mail：zongygou@qq.com
  • 基金资助:
    国家自然科学基金项目(41702069，41730426)；内生金属矿床成矿机制研究国家重点实验室开放研究基金项目(2017-LAMD-K05)；西部矿产资源与地质工程教育部重点实验室开放基金项目(310826171109)；博士后国际交流计划派出项目(20170108)；中国地质大学(北京)基本科研业务费项目(2652018125，2652018141)和高等学校学科创新引智计划(B07011)

Oxygen fugacity of ore-bearing porphyries in the Taiyangshan porphyry copper-molybdenum deposit, West Qinling, China and its implications for porphyry-style Cu-Mo mineralization

GOU Zongyang,YU Haocheng,QIU Kunfeng,WU Mingqian,ZHOU Chunsheng, ZHU Rui,LI Jun,WEN Yitong   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences(Beijing); State Key Laboratory of Geological Processes and Mineral Resources, Beijing 100083, China
    2. State Key Laboratory for Mineral Deposits Research, Nanjing University, Nanjing 210023, China
    3. Department of Geology and Geological Engineering, Colorado School of Mines, Golden CO 80401, USA
    4. Zhaojin Mining Industry Co., LTD, Zhaoyuan 265400, China
  • Received:2019-05-31 Revised:2019-07-25 Online:2019-09-28 Published:2019-09-28
  • Supported by:
     

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摘要： 甘肃天水三叠纪太阳山斑岩铜钼矿床位于西秦岭造山带东段。矿体主要赋存于石英闪长斑岩、二长斑岩、石英二长斑岩和泥盆系大草滩群。氧逸度是表征岩石物理化学性质的重要参数，对岩浆热液成矿具有明显的控制作用。在综合评述常用氧逸度计算方法及适用性的前提下，文中应用激光剥蚀等离子质谱分析方法对太阳山矿床含矿岩体锆石微量元素进行测定，选用含量较高的Sm、Nd进行Ce异常计算，查明含矿斑岩岩浆氧逸度，探讨其成矿意义。太阳山矿床岩浆氧逸度计算结果表明，太阳山成矿二长斑岩和石英二长斑岩相对氧逸度ΔFMQ分别为+3.04和+3.15，成矿前石英闪长斑岩相对氧逸度ΔFMQ为-1.83，成矿岩体氧逸度明显高于成矿前岩体。成矿岩体岩浆氧逸度高于成矿前岩体的原因可能与富集地幔有关。富集岩石圈地幔的加入，带来了大量的硫和金属铜，并提高了岩浆氧逸度。

 

关键词: 太阳山矿床, 氧逸度, 斑岩型矿床, 西秦岭

Abstract: The Triassic Taiyangshan porphyry copper-molybdenum deposit in Tianshui City, Gansu Province is tectonically located in the West Qinling Orogenic Belt. The bulk of Cu-Mo mineralization is associated with monzonite porphyry and quartz monzonite porphyry, and occurs as stockwork veinlets and disseminated ores in the porphyries and the surrounding Devonian host rocks. Oxygen fugacity is an important physical-chemical parameter in petrology and an obvious controlling factor in magmatic-hydrothermal mineralization. We conducted LA-ICP-MS trace elemental analyses on zircons from the ore-hosting porphyries at Taiyangshan, aiming at calculating the magma oxygen fugacity and constraining its ore formation implications. The average oxygen fugacities were ΔFMQ+3.04 and ΔFMQ+3.15 for ore-bearing monzonite porphyry and quartz monzonite porphyry, respectively, characterized by high f(O2) values. The pre-mineralization quartz diorite porphyry, however, yielded an average oxygen fugacity of ΔFMQ-1.83, a much lower f(O2) value. Combined with our previous petrogenesis results, we therefore proposed that the oxidized magma is associated with enriched mantle, whose addition brought sulfur and copper while increased oxygen fugacity.

Key words: Taiyangshan deposit, oxygen fugacity, porphyry deposit, West Qinling

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