| 中国不同类型铍矿床中绿柱石流体包裹体特征研究 |
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| 关键词:beryl fluid inclusion petrography characteristics ingredient characteristics formation mechanism |
| 基金项目:国家自然科学基金项目(编号: 42172007);中国地质调查局“中国矿产地质志”项目(编号: DD20221695; 20190379; DD20160346) |
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| Characteristics of Fluid Inclusions in Beryl from Different Beryllium Deposits in China |
| The fluid inclusions in beryl in pegmatitic and magmatic hydrothermal beryllium deposits were studied using polarizing microscope observations of thin sections and laser Raman composition analysis. The results showed that the primary fluid inclusions in beryl had various forms. Beryl was usually distributed in isolation or in groups along the crystal growth zone, ranging in size from 5 μm to 80 μm. Liquid-rich gas–liquid two-phase inclusions were the most common types of fluid inclusions, followed by liquid-phase CO2-containing three-phase inclusions and multiphase inclusions containing daughter minerals. Occasionally, solid inclusions and melt inclusions were also observed. Pegmatitic beryl had substantial quantity and variety of inclusions, and it was common to have multiphase inclusions with carrier crystals and gas-liquid inclusions. However, there were relatively few inclusions in magmatic hydrothermal beryl, and melt inclusions coexisted with liquid-rich CO2 fluid inclusions. The gaseous components of the fluid inclusions were primarily CO2 and N2, and the liquid phase was primarily H2O, CO2, CO2– 3, HCO– 3, and other ions. Pegmatitic beryl often contained multiphase inclusions containing quartz, mica, albita, and other daughter minerals, which are formed by the rapid crystallization of pegmatitic crystals. Organic gas, which is related to the relative reduction environment formed by the low activity of the oxidant Al2O3, was more abundant in magmatic hydrothermal beryl. Fluids rich in CO2 and H2O were more conducive to the formation of beryl. Combined with the formation mechanism of fluid inclusions, it is suggested that magmatic hydrothermal beryl was formed in the hydrothermal stage of late magmatic evolution. Pegmatitic beryl was formed during the transition from the magmatic-hydrothermal stage to the hydrothermal stage. The formation mechanism of beryl is crystal differentiation and liquid immiscibility of magma. |
| DONG Jing-yu,HUANG Fan,WEI Na.2023.Characteristics of Fluid Inclusions in Beryl from Different Beryllium Deposits in China[J].Acta Geoscientica Sinica,44(4):635-648. |
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