| 云南北衙超大型金多金属矿床斑岩阶段成矿流体演化——来自流体包裹体并结合H-O同位素的约束 |
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| 关键词:porphyry-stage veins microthermometry of fluid inclusions ore-forming fluid evolution Beiya gold polymetallic deposit |
| 基金项目:本文由自然资源部科技创新发展项目(编号: 102121191130000009001)和自然资源科普与重大科技成果宣传项目(编号: 102121191130000009001)联合资助。 |
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| Porphyry-stage Ore-forming Fluid Evolution in the Giant Beiya Au Polymetallic Deposit, Yunnan, China: Fluid Inclusion and H-O Isotopic Constraints |
| The Beiya Au polymetallic deposit, a giant porphyry–skarn system in the Jinshajiang–Red River alkali-rich porphyry metallogenic belt, is characterized by porphyry Cu(-Mo)-Au, skarn Au-Cu-Fe, and distal Pb-Zn-Ag mineralization. Previous studies have focused mainly on skarn-related and composite hydrothermal stages, whereas studies on fluid evolution recorded by porphyry-stage veins and its role in Cu-Mo-Au precipitation remain scarce. This study focuses on porphyry-stage A, B, and D veins, using fluid inclusion petrography and microthermometry, combined with published H-O isotopic data, to constrain the source, evolution, and metal precipitation processes of the ore-forming fluids. A veins contain VL, LV, and LVH inclusions with homogenization temperatures of 207–438 °C and salinities of 3.33–47.66 wt. % NaCl equiv., indicating an early magmatic–hydrothermal fluid with pronounced phase and salinity heterogeneity that caused potassic alteration with limited sulfide precipitation. B veins contain coexisting VL, LV, and LVH inclusions with broad temperature-salinity ranges and two salinity populations, are characterized by abundant chalcopyrite, pyrite, and molybdenite, suggesting that depressurization-related boiling or phase separation was a key trigger for Cu-Mo-Au deposition. D veins dominated by LV inclusions are associated with sericitization and abundant sulfides with generally lower temperatures and salinities. Combined with H-O isotopic compositions trending toward meteoric water, these features indicate that late-stage meteoric water input promoted fluid dilution, cooling, and destabilization of metal complexes. Overall, Cu-Mo-Au enrichment during the porphyry stage at Beiya may be controlled by early magmatic fluid exsolution, B-vein boiling/phase separation, and D-vein fluid mixing, providing constraints on the porphyry–skarn composite ore-forming system. |
| ZHOU Xiangke,ZHANG Xihuan,WANG Jiaxuan.2026.Porphyry-stage Ore-forming Fluid Evolution in the Giant Beiya Au Polymetallic Deposit, Yunnan, China: Fluid Inclusion and H-O Isotopic Constraints[J].Acta Geoscientica Sinica,47(5):971-986. |
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