| 西藏列廷冈-勒青拉铅锌铁铜钼矿床成矿流体特征:来自流体包裹体及碳氢氧同位素的证据 |
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| 引用本文： | 马旺,刘英超,杨竹森,李振清,赵晓燕,岳龙龙.西藏列廷冈-勒青拉铅锌铁铜钼矿床成矿流体特征:来自流体包裹体及碳氢氧同位素的证据[J].地球科学,2019,44(6):1957-1973. |
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| 作者姓名： | 马旺 刘英超 杨竹森 李振清 赵晓燕 岳龙龙 |
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| 作者单位： | 1.中国地质科学院地质研究所, 北京 100037 |
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| 基金项目： | "深地资源勘查开采"重点专项2016YFC0600306国家自然科学基金41773042国家自然科学基金41773043国家自然科学基金41320104004国家自然科学基金41772088中国地质调查局项目DD20160024-02国际地质对比计划IGCP-662 |
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| 摘 要： | 列廷冈-勒青拉矿床位于西藏冈底斯北缘多金属成矿带东侧,是该成矿带内一个独特的同时发育Pb、Zn、Fe、Cu、Mo五种元素矿化的典型矽卡岩型矿床.对该矿床成矿流体性质研究有助于解决这种具有不同来源属性的多金属共生矿床的成矿机制等科学问题.基于此,选取与Fe-Cu-Mo矿化和Pb-Zn-Cu矿化密切相关的矽卡岩矿物和脉石矿物,系统开展了流体包裹体和碳氢氧同位素研究,结果显示二者的成矿流体来源相同并经历了相似的演化过程.矽卡岩阶段主要发育富液相包裹体,成矿流体具有高温中高盐度特征.成矿期石英硫化物阶段和成矿后期碳酸盐阶段主要发育富液相包裹体和含子晶的多相包裹体,前者成矿流体温度属于中高温范畴,而盐度分为高盐度和低盐度两类;后者成矿流体温度属于中低温范畴,而盐度同样分为高盐度和低盐度两类,研究表明出现两种盐度截然不同的流体是由于沸腾作用造成的.稳定同位素研究结果显示矽卡岩阶段成矿流体主要源于发生过脱水去气作用的残余岩浆水,石英硫化物阶段和碳酸盐阶段均有大气降水的参与.灰岩地层与正常海相碳酸盐岩相比δ18O明显亏损,表明成矿流体在矿区灰岩地层中大规模运移并发生水岩反应,从而在远端矽卡岩带形成铅锌铜矿化.结合前人及本次研究结果,列廷冈-勒青拉矿床Fe-Cu矿化与Pb-Zn矿化为同一时期岩浆活动的产物,但分别与不同属性的岩浆有关.降温冷却、流体混合作用以及pH值的变化是控制列廷冈-勒青拉矿床金属沉淀的重要因素,而成矿温度和岩浆属性的差异是造成成矿元素在空间上分带的主要原因.
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| 关 键 词： | 流体包裹体 碳氢氧同位素 铅锌铁铜钼矿床 列廷冈-勒青拉 西藏 矿床 |
| 收稿时间： | 2018-09-08 |
Characteristics of Ore-Forming Fluids of Lietinggang-Leqingla Pb-Zn-Fe-CuMo Polymetallic Deposit in Tibetan: Evidence from Fluid Inclusions and Stable Isotope Compositions |
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| Ma Wang,Liu Yingchao,Yang Zhusen,Li Zhenqing,Zhao Xiaoyan,Yue Longlong.Characteristics of Ore-Forming Fluids of Lietinggang-Leqingla Pb-Zn-Fe-CuMo Polymetallic Deposit in Tibetan: Evidence from Fluid Inclusions and Stable Isotope Compositions[J].Earth Science-Journal of China University of Geosciences,2019,44(6):1957-1973. |
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| Authors: | Ma Wang Liu Yingchao Yang Zhusen Li Zhenqing Zhao Xiaoyan Yue Longlong |
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| Institution: | (Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China) |
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| Abstract: | The Lietinggang-Leqingla deposit developed Pb-Zn-Fe-Cu-Mo five kinds of metals in the same ore district, which is the most typical skarn-type deposit in the north Gangdese polymetallic belt.Studying on the ore fluid property is helpful for us to solve the ore-forming mechanism of this deposit, which is considered to be polymetallic symbiosis deposit with different source attributes. In this study, skarn minerals and gangue minerals closely related to Fe-Cu-Mo and Pb-Zn-Cu mineralization were sampled and a detailed study with regard to fluid inclusion and C-H-O isotopes was conducted, the results show that the fluid source and evolution process of the ore blocks are similar. There are mainly liquid-rich fluid inclusions in the sakrn alteration stage, and fluid in this stage has high temperatures and medium -high salinities.There are mainly liquid -rich fluid inclusion and daughter mineral-bearing fluid inclusions in the quartz-sulfide stage and carbonate stage, fluid in the quartz-sulfide stage has medium-high temperature, and salinity can be divided into high salinity and low salinity.Fluid in the carbonate stage has medium-low temperature, and salinity also can be devided into high salinity and low salinity. Studies show that the presence of two fluids with very different salinity results from boiling of the ore-forming fluid. Stable isotope compositions indicate that the ore-forming fluids were derived from magmatic hydrothermal fluid which had undergone degasification in skarn alteration stage and was mixed with meteoric water in quartz sulfide stage and carbonate stage. The δ18O is obviously depleted in the limestone strata compare with the normal marine limestone, which indicate that the ore-forming fluid had large-scale migration and water-rock interaction in the whole limestone strata of ore district, thus the Pb-Zn-Cu mineralization is formed in the distal skarn belt. This study, combined with previously published data, Fe-Cu and Pb-Zn mineralization of the Lietinggang-Leqingla deposit are the products of magmatic activities in the same period, but they are related to magma of different attributes. Cooling, fluid mixing and variation of pH of ore-forming fluid resulted in the precipitation of metal of the Lietinggang-Leqingla deposit, the mineralization zoning from the Lietinggang-Leqingla deposit was mostly like controlled by the difference of metallogenic temperature and magmatic attribute. |
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| Keywords: | fluid inclusion hydrogen oxygen and carbon isotopes Pb-Zn-Fe-Cu-Mo polymetallic deposit Lietinggang-Leqingla Tibet deposits |
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