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现代地质 ›› 2017, Vol. 31 ›› Issue (04): 672-682.

• 岩石学 • 上一篇    下一篇

甘肃省沃尔给花岗岩体中黑云母的成分对其岩体碱度的响应及成岩成矿意义

杜佰松1(), 申俊峰1(), 秦玉良2, 刘海明3, 刘圣强1, 徐立为1, 牛刚2, 欧阳尔彪2   

  1. 1.中国地质大学(北京) 地球科学与资源学院,北京100083
    2.甘肃鼎丰矿业有限责任公司, 甘肃 兰州 730000
    3.加拿大拉瓦尔大学 地质与地质工程系,魁北克 拉瓦尔 G1V 0A6
  • 收稿日期:2016-06-23 修回日期:2016-12-25 出版日期:2017-08-10 发布日期:2017-09-15
  • 通讯作者: 申俊峰,男,教授,博士生导师,1962年出生,矿物学、岩石学、矿床学专业,主要从事成因矿物学与找矿矿物学方向研究。Email:shenjf@cugb.edu.cn
  • 作者简介:杜佰松,男,硕士研究生,1986年出生,地质工程专业,从事成因矿物学与找矿矿物学方向研究。Email:979631176@qq.com
  • 基金资助:
    国家自然科学基金项目(41072070)

Chemical Composition of Biotites Responding to Basicity of Woergei Granite Intrusion in Gansu Province and Implications for Petrogenesis and Mineralization

DU Baisong1(), SHEN Junfeng1(), QIN Yuliang2, LIU Haiming3, LIU Shengqiang1, XU Liwei1, NIU Gang2, OUYANG Erbiao2   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences,Beijing 100083,China
    2. Gansu Dingfeng Mining Company Limited, Lanzhou, Gansu 730000,China
    3. Department of Geology and Geological Engineering, Université Laval, Laval Quebec, G1V 0A6, Canada
  • Received:2016-06-23 Revised:2016-12-25 Online:2017-08-10 Published:2017-09-15

摘要:

矿床的形成与其成矿地质体的成因和岩石化学性质密切相关,因此有必要对岩体碱度与成矿关系进行深入研究。通过甘肃省沃尔给花岗岩体的采样测试,并对国内52个各类矿床中与成矿有关岩体中黑云母的主量元素化学成分进行统计和分析,进行寄主岩石碱度判别。研究结果显示:研究区与Cu、Au成矿有关的岩体位于高碱度区域内,而与Sn矿形成有关的岩体均属于低碱度岩石系列。岩浆熔体早期至岩浆后期热液阶段,氧逸度的变化由高到低,介质的碱度逐渐增强,Cu、Au矿床的形成大致经历上述的成岩成矿过程。岩浆结晶过程早期低氧逸度、高碱度有利于Sn的活化迁移,岩浆期后热液阶段的高氧逸度、低碱度有利于锡石的沉淀,但是由于锡石沉淀过程中不断消耗O2,致使其较高的氧逸度显著降低。认为碱度与氧逸度之间相互作用、相互影响进而引起矿化的发生。

关键词: 黑云母, 成因, 碱度, 氧逸度, 沃尔给花岗岩体, 甘肃省

Abstract:

The formation of ore deposits and the geological genesis of metallogenic rock mass are closely related to the chemical characteristics of rocks. In this paper, we centred on the investigation of relationship between the alkalinity and mineralization. The sampling and measurement of the chemical compositions of biotite, from Woergei granite intrusion in Gansu Province are carried on, and the biotite data from fifty-two kinds of different deposits in China are collected. By analyzing the basicity of host rocks, we regard that the existed metallogenic granite intrusion bearing Cu and Au were located in the high basicity area. The granite intrusion was almost related to the formation of Sn ore deposits belong to the low alkalinity rock. From the early to late period of magmatic melt transformation process, the oxygen fugacity changed from high to low and medium alkalinity increased. The formation of Cu and Au deposits was also followed by the process of diagenetic mineralization. However, the low oxygen fugacity and the high basicity are advantageous to the activation and migration of element Sn in early magmatic crystallization process. The high oxygen fugacity and the lower alkalinity are advantageous to the precipitation of cassiterite in magmatic hydrothermal-fluid stage. The precipitation of cassiterite constantly consumed oxygen, leading to a significant decrease of the higher oxygen fugacity than before. The interaction of the oxygen fugacity and the basicity caused mineralization.

Key words: biotite, genesis, basicity, oxygen fugacity, Woergei granite intrusion, Gansu Province

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