| 湘东北雁林寺矿集区金矿富集机制——流体包裹体与同位素证据 |
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| 关键词:gold mineralization carbon-hydrogen-oxygen isotope fluid inclusion Yanlinsi gold ore concentration area northeastern Hunan Province |
| 基金项目:国家重点研发计划“深地资源勘查开采”重点专项课题(编号: 2017YFC0601500)；中国矿产地质志项目(编号: DD20221695; DD20190379; DD20160346)、湖南省自然科学基金项目(编号: 2023JJ60164)；湖南省自然资源厅科研项目(编号: 2017-03; 2019-02)；湖南省地质院科研项目(编号: HNGSTP202423; 2017-01-01; 201902-01; 201917; 2021YSP-05) |
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| Enrichment Mechanism of Gold in the Yanlinsi Gold Ore Concentration Area, Northeastern Hunan: Evidence from Fluid Inclusions and Isotopes |
| The Yanlinsi gold ore concentration area, located in northeastern China, remains one of the single gold deposit bases in Hunan Province. The mechanism of gold precipitation and enrichment in this area has been widely debated among scholars, and determining the metallogenic mechanism of gold deposits is crucial for guiding the prospecting of precious metal gold. This study identifies the evolution process of ore-forming fluids and the key mechanism of changes in fluid geochemical conditions that restrict gold enrichment and mineralization in the area by examining the temperature, pressure, gas-liquid phase composition, and isotopic compositions of fluid inclusions. Petrography and microthermometry of the fluid inclusions revealed the presence of CO2-containing inclusions (C-type) and aqueous inclusions (W-type) in the gold deposits of the study area. The homogenization temperature range of the inclusions in Tuanshanbei and Yanlinsi deposits is 143–231 ℃ and the salinity range is (2–9) wt%, indicating that the ore-forming fluid is a CO2-H2O-NaCl system with low temperature and low salinity. The δ18O value of the ore-forming fluid in the gold ore concentration area range from 4.5‰ to 9.7‰, and the δD value range from –66.8‰ to –46‰. The δ13CVPDB value of the calcites range from –4.7‰ to –3.7‰, and δ18OSNOW value range from 10.6‰ to 15.0‰. The δD-δ18O binary diagram of the gold ore concentration area suggests that the ore-forming fluid may be metamorphic water or magmatic water. The C-H-O isotope composition of the ore concentration area indicated that the ore-forming fluid is likely metamorphic water, consistent with the results of the fluid inclusion characteristics. Au exists and migrates in the form of an Au(HS)– 2 complex within the low-temperature and low-salinity CO2-H2O-NaCl metamorphic fluid system, with the addition of atmospheric water, and Au deposits are formed by fluid immiscibility. |
| TAN Shimin,HUANG Jianzhong,SUN Ji,DU Yun,CHEN Qiliang,CAO Chuanghua.2024.Enrichment Mechanism of Gold in the Yanlinsi Gold Ore Concentration Area, Northeastern Hunan: Evidence from Fluid Inclusions and Isotopes[J].Acta Geoscientica Sinica,45(6):913-925. |
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