The characteristics of ore-forming fluid and mineralization mechanism in the Huzhagaitu porphyry Mo deposit, Inner Mongolia

被引：0
|
作者：
Liu R. [1 ,2 ,3 ]
Liu Z. [4 ]
Mi K. [4 ,5 ]
Li C. [6 ]
Wang J. [4 ]
机构：
[1] Institute of Geology, Chinese Academy of Geological Sciences, Beijing
[2] School of Earth and Space Sciences, Peking University, Beijing
[3] Department of Geology and Environmental Engineering, Shanxi Institute of Technology, Yangquan, 045000, Shanxi
[4] School of Earth Sciences and Resources, China University of Geology, Beijing
[5] Development and Research Center, CGS, Beijing
[6] Beijing Research Institute of Chemical Engineering and Metallurgy, CNNC, Beijing
来源：
Dizhi Xuebao/Acta Geologica Sinica | 2019年 / 93卷 / 09期
关键词：
Fluid boiling; Fluid inclusions; Huzhagaitu; Ore-forming fluid; Porphyry molybdenum deposit;
D O I：
10.19762/j.cnki.dizhixuebao.2019193
中图分类号：
学科分类号：
摘要：
The Huzhagaitu molybdenum deposit is a newly discovered porphyry deposit in the middle segment of the Derbugan metallogenic belt in Inner Mongolia. The molybdenum orebodies are mainly hosted within the Early Yanshan granodiorite, and its contact zone with rhyolite. The deposit is dominated by molybdenum mineralization and pyrite mineralization, accompanied by lead-zinc mineralization and a small amount of copper mineralization. The ore-forming process can be divided into four stages: silicification stage, quartz-molybdenum stage, quartz-polymetallic sulphide stage, and quartz-calcite stage. There are four types of fluid inclusions: liquid-rich phase inclusions, vapor-rich phase inclusions, multiphase inclusions including daughter minerals and CO2-bearing three-phase inclusions. With the main mineralization stage as the focus of our research, this study carried out microscopic temperature measurement and laser Raman microprobe analysis for the inclusions in quartz or calcite in different mineralization stages (stage II to IV). The results show that the homogenization temperatures of the inclusions in the quartz-molybdenum-pyrite stage are mainly concentrated between 280℃ and 400℃, and the salinities vary from 2.57% to 51.68%. In this stage, vapor-rich phase inclusions and multiphase inclusions including daughter minerals coexist with CO2-bearing three-phase inclusions. The liquid phase composition of L-type inclusions is mainly H2O-NaCl. The gas phase composition of V-type inclusions is mainly H2O, and some of them also contain CO2. Characteristic peak of laser Raman shift of daughter mineral chalcopyrite was detected in halite-bearing three phase inclusions. In the quartz-pyrite stage with lead-zinc mineralization and chalcopyrite mineralization, the homogenization temperatures of the inclusions are concentrated between 180℃ and 280℃, and the salinities vary from 0.18% to 9.73%. In late stage, only L-type inclusions occur in quartz-calcite veins, with the homogenization temperatures mainly ranging between 140℃ and 240℃, salinities varying from 0.35% to 7.17%. Combined with the latest research results, this paper suggests that the initial fluid of the deposit was magmatic fluid characterized by medium salinity and medium density. In the main stage of mineralization, the boiling of ore-forming fluid due to pressure release resulted in sudden change of the physical and chemical conditions of the ore-forming fluid system and the oxidation-reduction environment, causing the unloading and precipitation of molybdenite and other sulfide minerals in vein fractures. © 2019, Science Press. All right reserved.
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页码：2330 / 2347
页数：17
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共 56 条
  • [1] Bodnar R.J., Revised equation and table for determining the freezing point depression of H<sub>2</sub>O-NaCl solutions, Geochimica et Cosmochimica Acta, 57, 3, pp. 683-684, (1993)
  • [2] Brown P.E., Flincor: A microcomputer program for the reduction and investigation of fluid-inclusion data, American Mineralogist, 74, 11-12, pp. 1390-1393, (1989)
  • [3] Cao X., Solubility of molybdenite and the transport of molybdenum in hydrothermal solutions, pp. 1-103, (1989)
  • [4] Chen Y., Ni P., Fan H., Pirajno F., Lai Y., Su W., Zhang H., Diagnostic fluid inclusions of different types hydrothermal gold deposit, Acta Petrologica Sinica, 23, 9, pp. 2085-2108, (2007)
  • [5] Chen Y., Zhang C., Li N., Yang Y., Deng K., Geology of the Mo deposits in northeast China, Journal of Jilin University(Earth Science Edition), 42, 5, pp. 1221-1268, (2012)
  • [6] Chen Z., Zhang L., Hydrogen and oxygen isotope fractionation mechanism in the hydrothermal system and its geologic significance, Acta Geologica Sinica, 66, 2, pp. 158-169, (1992)
  • [7] Chen Z., Oxygen and hydrogen isotope behavior in hydrothermal water-rock interaction process, Geotectonica et Metallogenia, 21, 1, pp. 51-61, (1997)
  • [8] Chen Z., Zhang L., Lu B., Li Z., Wu H., Xiang P., Huang S., Geochronology and geochemistry of the Taipingchuan copper-molybdenum deposit in Inner Mongolia, and its geological significances, Acta Petrologica Sinica, 26, 5, pp. 1437-1449, (2010)
  • [9] Chi G., Lai J., Roles of fluid inclusions in study of mineral deposits, Mineral Deposits, 28, 6, pp. 850-855, (2009)
  • [10] Chi G., Xue C., Principles, methods and applications of hydrodynamic studies of mineralization, Earth Science Frontiers, 18, 5, pp. 1-18, (2011)
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