| 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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| 引用本文：肖勇,张雨晴,杨文春,朱文祥,施文超,王杰,杨洪杰.2026.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[J].地球学报,47(1):65-77. |
| DOI：10.3975/cagsb.2025.092511 |
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| 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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| 中文摘要:大型断裂与岩溶复合区域水热活动机制复杂, 厘清地热水成因是实现其地热资源科学合理开发利用的关键。本文以小江断裂南段热水塘地热泉群为研究对象, 通过系统采集区域冷、热水样, 综合运用水文地球化学、环境同位素及地质水文地质分析手段, 探究断裂带与岩溶发育对地热水形成、出露过程的控制作用。研究发现, 热水塘地热泉水出露温度48.2~50.6 ℃, pH值6.6~7.0, TDS值784~851 mg/L, 其水化学特征显著区别于抚仙湖临岸湖水与区域冷泉水。地热系统补给水源为抚仙湖湖盆东南火特村南部山区(高程 2 531~2 716 m)大气降水; 补给水沿断裂与岩溶通道下渗至2 145~2 447 m深处, 热储层温度为179~201 ℃, 地下滞留时间长达24~28 ka; 地热水与围岩发生了充分水岩作用, 但其在径流至排泄区浅表时遭遇岩溶通道控制的大量浅循环冷水混入(冷水混入比例86%~89%), 改变了其水化学组成并破坏了水化学平衡状态, 最终在抚仙湖湖岸出露形成富集SiO2(40.5~43.1 mg/L)、砷(0.05~0.06 mg/L)、氟(1.50~1.68 mg/L)等特征组分的中性至弱碱性低温地热泉水。 |
| 中文关键词:水热型地热 地热水 成因模式 出露机制 岩溶 抚仙湖 |
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| Hydrogeochemical Characteristics and Formation Mechanisms of Typical Geothermal Spring Groups in the Southern Xiaojiang Fault Zone |
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| Abstract: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). |
| keywords:hydrothermal resource geothermal water genetic model discharge regime karst Fuxian Lake |
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