| 云南南秧田钨矿床流体包裹体特征及其意义 |
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| 引用本文： | 冯佳睿,周振华,程彦博.云南南秧田钨矿床流体包裹体特征及其意义[J].岩石矿物学杂志,2010,29(1):50-58. |
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| 作者姓名： | 冯佳睿 周振华 程彦博 |
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| 作者单位： | 1. 中国地质科学院,矿产资源研究所,北京,100037
2. 中国地质大学,地球科学与资源学院,北京,100083 |
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| 基金项目： | 中央级公益性科研院所基本科研业务费专项资金，国家重点基础研究课题，国家自然科学重点基金资助项目 |
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| 摘 要： | 对南秧田矽卡岩型钨矿床的石英和石榴石流体包裹体的岩相学特征研究表明,与成矿有关的包裹体主要有3类:富液相、富气相和含子晶的多相包裹体。石英包裹体均一温度范围为232～337℃,盐度w(NaCl)=0.53%～9.98%;石榴石包裹体的均一温度范围为228～306℃,盐度w(NaCl)=6.45%～14.04%。激光拉曼探针分析表明,南秧田白钨矿的成矿流体中气相成分以H2O为主,含少量CO2、CH4、H2S和N2等气体,液相成分以H2O为主,属NaCl-H2O流体体系。成矿溶液的密度为0.72～0.87g/cm3,表明形成这种矽卡岩型矿床的成矿流体均属于中温、低盐度、低密度的流体。成矿压力为18～32MPa,成矿深度约为0.6～1.2km。石英包裹体水的δD为-72.16‰～-65.10‰,δ18O为7.98‰～8.45‰,钨矿床中硫化物δ34S为6.6‰。成矿流体主要来自燕山晚期的岩浆热液作用。
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| 关 键 词： | 南秧田 矽卡岩型钨矿床 流体包裹体 激光拉曼探针分析 成矿机制 |
Characteristics and significance of the fluid inclusions from the Nanyangtian tungsten deposit in Yunnan Province |
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| FENG Jia_rui,ZHOU Zhen hua and CHENG Yan bo.Characteristics and significance of the fluid inclusions from the Nanyangtian tungsten deposit in Yunnan Province[J].Acta Petrologica Et Mineralogica,2010,29(1):50-58. |
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| Authors: | FENG Jia_rui ZHOU Zhen hua and CHENG Yan bo |
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| Institution: | Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;Faculty of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China |
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| Abstract: | South China is the largest and the most specific tungsten metallogenic belt in the world, Jurassic is the main ore-forming period of tungsten ore deposits in South China, and Cretaceous is the main mineralization period of tin ore deposits in China. Nevertheless, the Nanyangtian skarn-type scheelite deposit in Yunnan Province is closely linked with the Cretaceous granites in space and time and is the only skarn-type tungsten deposit discovered in Cretaceous strata. The ore-bearing rock series of the Nanyangtian skarn-type tungsten deposit comprise alternating layers composed of skarns, gneiss, granulite, schist and some other rocks, in which skarn layers are the main ore-hosting rocks and skarn scheelite is the main ore type. This paper deals with micro temperature measurement and Laser Raman spectroscopy of fluid inclusions in the Nanyangtian tungsten deposit, aimed at discriminating ore-forming fluid properties of this deposit and clarifying its ore-forming material source and metallogenic mechanism based on petrographic characteristics for the further study of the Nanyangtian skarn-type tungsten deposit. There are three dominant types of fluid inclusions related to metallogensis, as evidenced by petrographic characteristics of fluid inclusions of quartz and garnet in the Nanyangtian skarn-type tungsten deposit; they are liquid-rich inclusions, gas-rich two-phase inclusions and daughter minerals-bearing polyphase inclusions. The homogenization temperatures and salinity of fluid inclusions in quartz range from 232℃ to 337℃ and from 0.53% to 9.98 wt% NaCleqv respectively, and those of the inclusions in garnet vary from 228℃ to 306℃ and from 6.45% to 14.04 wt% NaCleqv respectively. Laser Raman spectroscopy shows that the gas composition of ore-forming fluids in Nanyangtian scheelite is mainly H_2O, with a small amount of CO_2, CH_4, H_2S, N_2 and some other gases, whereas liquid composition is mainly H_2O, thus suggesting a NaCl-H_2O fluid system. The density of the fluids is 0.72～0.87 g/cm~3. These features demonstrate that the fluids in this tungsten deposit are of medium temperature, low salinity and low density. The pressure of the fluid is 18～32 MPa, the depth of the fluid is 0.6～1.2 km, the δD values range from -72.16‰ to -65.10‰, the δ~(18)O water values vary from 7.98‰ to 8.45‰, and the δ~(34)S value of sulfides in the tungsten deposit is 6.6‰. These data imply that ore-forming fluids were derived from the magmatic hydrothermal process in late Yanshanian period, and magmatism caused the remobilization and enrichment of ore-forming elements to form the Nanyangtian skarn-type tungsten deposit. |
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| Keywords: | Nanyangtian skarn-type tungsten deposit fluid inclusion Laser Raman spectroscopy metallogenic mechanism |
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