地学前缘 ›› 2018, Vol. 25 ›› Issue (1): 168-181.DOI: 10.13745/j.esf.yx.2018.01.012

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内蒙古维拉斯托锡多金属矿流体包裹体特征

郭理想,刘建明,曾庆栋,蒋胡灿,刘红涛   

  1. 1. 中国科学院 地质与地球物理研究所 中国科学院矿产资源研究重点实验室, 北京 100029
    2. 中国科学院大学, 北京 100049
    3. 内蒙古维拉斯托矿业有限公司, 内蒙古 赤峰 025350
  • 收稿日期:2017-05-09 修回日期:2017-10-07 出版日期:2018-01-15 发布日期:2018-01-15
  • 作者简介:郭理想(1989—),男,博士研究生,矿物学、岩石学、矿床学专业。E-mail:glx.1989@163.com
  • 基金资助:
    国家自然科学基金重点项目(41390443);国家重点研发计划项目(2017YFC0601306)

Fluid inclusion characteristics of the Weilasituo Sn polymetallic ore deposit, Inner Mongolia, China

GUO Lixiang,LIU Jianming,ZENG Qingdong,JIANG Hucan,LIU Hongtao   

  1. 1. Key Laboratory of Mineral Resource, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
    2. University of Chinese Academy of Sciences, Beijing 100049, China
    3. Inner Mongolia Weilasituo Mining Company Limited, Chifeng 025350, China
  • Received:2017-05-09 Revised:2017-10-07 Online:2018-01-15 Published:2018-01-15

摘要: 大兴安岭锡矿带是中国北方唯一成型的锡多金属成矿带。新近发现的内蒙古维拉斯托锡多金属矿床位于大兴安岭南段,隶属中亚造山带东段的兴蒙造山带。该矿床为一典型的大型斑岩型热液脉型锡多金属矿床,矿区内锡矿化主要赋存于石英斑岩体顶部及其上部的石英脉中。矿床成矿阶段包括石英斑岩体内的滴状锡锌矿化阶段、石英斑岩体上部石英脉中的辉钼矿矿化阶段、石英锡石黑钨矿阶段和石英多金属硫化物阶段。流体包裹体研究结果显示:流体包裹体类型主要为气液两相包裹体,尤其是富液相包裹体,其次为含子矿物的三相包裹体。斑岩体内矿化阶段流体包裹体均一温度为324~333 ℃,盐度为6.5%~7.5% NaCleqv,密度为0.73~0.74 g/cm3;石英脉型矿化阶段包裹体均一温度为201~324 ℃,盐度为3.4%~9.9% NaCleqv,密度为0.73~0.92 g/cm3。包裹体显微测温分析结果显示该矿区成矿流体具有中高温、低盐度、中密度的特征。激光拉曼光谱分析表明,气液两相包裹体液相成分主要为H2O,气相成分主要有H2O、CO2和CH4。氢氧同位素研究结果表明该矿床石英斑岩体上部石英脉矿化阶段的成矿流体为岩浆水和大气降水混合来源,以岩浆水为主。岩浆流体与大气降水的混合以及流体演化中的降温过程是该矿床矿石沉淀的主要机制。

关键词: 大兴安岭锡矿带, 维拉斯托锡多金属矿, 流体包裹体, 成矿机制

Abstract: The Great Xingan Range tin metallogenic belt is the only mineable tinpolymetallic belt in northern China. The newly discovered Weilasituo Sn polymetallic ore deposit in Inner Mongolia, in the southern Great Xingan Range, is a part of the XinganlingMongolian Orogenic Belt in the eastern Central Asian Orogenic Belt. The deposit is a largescale porphyryhydrothermal vein type Snpolymetallic ore deposit, its mineralization is mainly hosted in the top portion of the quartz porphyry and quartz veins above it. Based on the crosscutting relationship of veins and ore structure, we recognized four metallogenic stages during the formation of the western Weilasituo SnZn polymetallic ore deposit, namely the dropletlike SnZn in quartzporphyry (stage Ⅰ), molybdenum (stage Ⅱ), quartzcassiteritewolframite (stage Ⅲ) and quartzpolymetallic sulphides (stage Ⅳ) mineralization. Fluid inclusions can be divided into three types: liquid and vaporrich twophase aqueous inclusions, and daughter mineralbearing threephase inclusion. Microthermometric analyses indicate that the homogenization temperature of dropletlike SnZn mineralization in quartz porphyry varied from 324 to 333 ℃, with salinity of 6.5%7.5% NaCleqv and density around 0.730.74 g/cm3. The fluid inclusions from quartz porphyrystyle mineralization exhibit a homogenization temperature range of 201324 ℃, with salinity and density of 3.4%9.9% NaCleqv and 0.730.92 g/cm3, respectively, consistent with the characteristics of moderatehigh homogenization temperature, low salinity and moderate density fluids in this deposit. The analytical results by laser raman spectroscopy suggest that the composition of the oreforming fluid is mainly H2O in the liquid phase and CH4, CO2 and H2O in the vapor phase. The data obtained by δ18O and δD analyses imply that the oreforming fluids in the quartz vein mineralization stage originated from the mixture of magmatic and meteoric waters, with magmatic water as the main component. Therefore, the principle mechanism for the deposit mineralization was mixing of magmatic and meteoric waters followed by a cooling period during fluid evolution.

Key words: Great Xingan Range tin metallogenic belt, Weilasituo Sn polymetallic ore deposit, fluid inclusion, mechanism of mineralization

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