| 辽西兰家沟钼矿床成矿流体特征及成因探讨 |
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| 引用本文：.2007.Ore_forming fluid characteristics and genesis of Lanjiagou molybdenum deposit in western Liaoning Province[J].Mineral Deposits,26(4):443~454 |
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| 基金项目:国土资源大调查项目（1212010634001） |
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| 中文摘要:兰家沟钼矿床是中国北方重要的独立钼矿床，矿体主要赋存于细粒花岗岩体内部及与粗粒花岗岩的接触部位，矿石类型以辉钼矿_石英大脉为主。流体包裹体研究表明，兰家沟钼矿床含钼石英脉中流体包裹体较少，类型主要为气液两相，个别含子矿物多相包裹体；激光拉曼光谱测试表明，成矿流体成分主要为H2O，微量的CO2、CO2-3。成矿期流体包裹体的均一温度为160～405℃，集中于180～320℃；盐度w(NaCleq)为2.4%～16.5%，多数在8%～14%。成矿流体在演化过程中发生了中等盐度和低盐度流体的混合作用，2种不同成分流体的混合作用使得辉钼矿大量沉淀而成矿。氢氧同位素研究表明，成矿流体的δD为-81‰～-101‰，δ18O水为-0.1‰～4.5‰，小于兰家沟花岗岩全岩δ18O水值，反映成矿流体来自混合的岩浆水与大气降水。通过与典型斑岩型钼矿床地质特征、矿化、围岩蚀变、流体包裹体特征及同位素组成的对比，认为兰家沟钼矿床属于热液脉型向斑岩型过渡类钼矿床。 |
| 中文关键词:地球化学 石英脉 流体包裹体 流体混合 矿床成因 兰家沟钼矿床 辽西 |
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| Ore_forming fluid characteristics and genesis of Lanjiagou molybdenum deposit in western Liaoning Province |
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| Abstract:Located in Liaoning Province, the Lanjiagou deposit is an important independent molybdenum deposit in northern China. Its major molybdenite ore bodies are situated within the fine_grained granite of Hongluoshan and the contact zone between the fine_grained granite and the coarse_grained granite. Large molybdenite_quartz veins constitute the main mineralization type in the Lanjiagou deposit. Detailed petrographic observation of ores from the Lanjiagou deposit shows that three types of primary fluid inclusions occur in quartz veins from the ores, i.e., aqueous two_phase inclusions (Ⅰ), daughter crystal_bearing polyphase inclusions (Ⅱ) and pure aqueous phase inclusions (Ⅲ), with more than 90% of the fluid inclusions belonging to type (Ⅰ). Microthermometric studies indicate that the homogenization temperatures and salinities of type Ⅰ fluid inclusions in ore_forming stage range from 160 to 405℃ and from 2.4% to 16.5% NaCl equivalent respectively, with most values in the range of 180～320℃ and 8%～14% NaCl equivalent. Laser Raman Spectroscopic analyses of fluid inclusions suggest that the ore_forming fluids were of the NaCl_H2O±(CO2) system.At the ore_forming stages,fluid mixing events occurred in two types of fluid inclusions with different compositions,which exerted positive influence on molybdenite precipitation and mineralization.The hydrogen and oxygen isotopic components of typical ores indicate that δD values of ore_forming fluids are from －81‰ to －101‰, while δ18OH2O from -0.1‰ to 4.5‰.The δ18OH2O values of the ore_forming fluids are lower than the values of the granite,suggesting that the ore_forming fluids might have been produced by mixing magmatic and meteoric water.Comparative studies of geological features,mineralization, wall rock alterations,fluid inclusion characteristics and H,O isotopes have led the authors to believe that there exist many differences between the Lanjiagou Mo deposit and the porphyry Mo deposit.The Lanjiagou deposit is genetically a transitional type Mo deposit from the Mo_bearing hydrothermal vein type to the porphyry Mo type. |
| keywords:geochemistry, quartz vein, fluid inclusion, fluid mixing, genesis, Lanjiagou molybdenum deposit, western Liaoning Province |
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