| 小江断裂带南段典型地热泉群水文地球化学特征及形成机制研究 |
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| 关键词:hydrothermal resource geothermal water genetic model discharge regime karst Fuxian Lake |
| 基金项目:由国家自然科学基金项目(编号: 42477059)、中央高校基本科研业务费专题研究项目(编号: 2682025ZTZD007)、云南省水文水资源局抚仙湖生态实验站建设项目(编号: FXHSYZ-KYSY-JS-202101)、中国地质科学院基本科研业务费项目(编号: JKY202406)和青海省科技计划项目(编号2024-ZJ-771)联合资助。 |
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| Hydrogeochemical Characteristics and Formation Mechanisms of Typical Geothermal Spring Groups in the Southern Xiaojiang Fault Zone |
| Hydrothermal processes in large-scale fracture-karst composite zones are governed by complex mechanisms. Unraveling the genesis of geothermal water is critical for the scientific and rational exploitation of such resources. This study focuses on the Reshuitang geothermal spring group in the southern segment of the Xiaojiang Fault Zone. By systematically collecting regional cold-and hot-water samples and using hydrogeochemical analysis, environmental isotope techniques, and an integrated geological-hydrogeological assessment, we elucidated the roles of the fault zone and karstification in the formation and discharge of geothermal water. The results show that the geothermal waters of Reshuitang spring group discharge at temperatures of 48.2–50.6 °C, with pH values of 6.6–7.0 and Total Dissolved Solids (TDS) ranging from 784 to 851 mg/L. Their hydrochemical characteristics are markedly distinct from both the nearshore waters of Fuxian Lake and cold spring waters. Meteoric precipitation within the 2 531–2 716 m elevation zone of the mountainous terrain south of Huote Village (southeastern Fuxian Lake basin) recharges the geothermal system. The recharge water percolates deeply, with a circulation depth of 2 145–2 447 m, via pathways provided by fractures and karst conduits. The reservoir temperature of the Reshuitang geothermal system reaches 179–201 °C. The groundwater’s estimated 24–28 ka residence time facilitated extensive water-rock interactions. However, during ascent to the shallow discharge zone, the geothermal water undergoes significant mixing with cold groundwater circulating in the shallow subsurface. This mixing, controlled by the prevalent karst development, results in cold water contributing 86%–89% to the final discharge. The mixing alters the water’s chemical composition and disrupts its chemical equilibrium state. Ultimately, the mixed water discharges as low-temperature (neutral to weakly alkaline) geothermal springs along the Fuxian Lake shoreline, characterized by elevated concentrations of specific components, notably SiO2 (40.5–43.1 mg/L), As (0.05–0.06 mg/L), and F (1.50–1.68 mg/L). |
| XIAO Yong,ZHANG Yuqing,YANG Wenchun,ZHU Wenxiang,SHI Wenchao,WANG Jie,YANG Hongjie.2026.Hydrogeochemical Characteristics and Formation Mechanisms of Typical Geothermal Spring Groups in the Southern Xiaojiang Fault Zone[J].Acta Geoscientica Sinica,47(1):65-77. |
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