| 大别造山带南缘芳畈矿集区成矿流体端元与物质来源：流体包裹体和原位S–Pb同位素约束 |
| 投稿时间：2026-06-01 修订日期：2026-08-11 |
| 关键词:Copper deposit Superimposed mineralization Magmatic hydrothermal fluid Brine Ore-forming materials Fangfan |
| 基金项目:湖北省自然科学基金项目（2023AFD230，2023AFD206，2024AFD401，2025AFD439）；资源与生态环境地质湖北省重点实验室开放基金项目（HBREGKFJJ-202402、HBREGKFJJ-202501、HBREGKFJJ-202505）；湖北省地质局科技项目（KJ2026-1）；地球深部探测与矿产资源勘查国家科技重大专项“武当-桐柏-大别成矿带金等多金属矿勘查增储与开发利用”（2025ZD1009107） |
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| 摘要: |
| Ore-forming fluid end-members and material sources of the vein-type copper deposits in the Fangfan ore field, Dabie Orogen: Constraints from fluid inclusions and in-situ S–Pb isotopes |
| Hydrothermal vein-type copper deposits are developed along the southern margin of the Dabie Orogen, yet their genesis and fluid characteristics remain controversial. This study integrates fluid inclusion microthermometry and in-situ sulfide S–Pb isotope analyses to characterize the ore-forming fluids and material sources, and to constrain the ore genesis of copper deposits in the Fangfan ore field. Based on field and petrographic observations, two periods of mineralization have been identified. Three independent fluid end-members are recognized: (1) a high-temperature, high-salinity end-member of magmatic-hydrothermal origin; (2) a low-temperature, high-salinity end-member representing formation brine derived from continental basin; and (3) a low-temperature, low-salinity endmember corresponding to meteoric water. The early-period ore-forming fluids are characterized by mixing between magmatic fluids and meteoric water, with chalcopyrite precipitation occurring under medium-to-high temperatures (288 to 315 °C) and low-to-medium salinities (3.9 to 19.3% NaCl eqv.). Sulfides from this period yield narrow δ³?S values (+0.10‰ to +4.30‰), and lead isotope compositions indicate a dominantly magmatic metal source. The late-period ore-forming fluids are characterized by mixing between brine and meteoric water, with sulfide precipitation occurring under low temperatures (<200 °C) and medium-to-high salinities (12.6 to 32.4 wt% NaCl eqv.). Sulfides from this period display a broader range of δ³?S values (+1.55‰ to +9.08‰), and lead isotope compositions confirm the involvement of sedimentary materials. The copper deposits in the Fangfan ore filed were formed through superimposed hydrothermal mineralization. The early-period mineralization is related to Early Cretaceous granitic magmatism in an extensional crustal setting, whereas the late-period mineralization is associated with graben basin development and brine activity. This study contributes to the understanding of superimposed metallogenesis at orogen–basin margins, and provides new insights for regional copper exploration. |
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