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EARTHQUAKE ›› 2025, Vol. 45 ›› Issue (2): 67-84.doi: 10.12196/j.issn.1000-3274.2025.02.005

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Hydrogeochemical Characterisation of Hot Springs of the Weixi-Qiaohou Fault

LI Jian1,2, LI Qing1,2, SHAO Wei-ye1, YOU Can1, WANG Zhi-hao1,2   

  1. 1. Yunnan Earthquake Agency, Kunming 650224, China;
    2. Northwestern Yunnan Crustal Tectonics Observatory of CEA, Dali 671000, China
  • Received:2024-04-29 Accepted:2024-05-29 Published:2025-09-05

Abstract: In this paper, 26 hot springs near the Weixi-Qiaohou fault are sampled and analysed to obtain the hydrochemical components of hot springs, such as temperature, ionic component and SiO2 content, and adopts the silicon-enthalpy model to estimate the hot spring’s geothermal reservoir temperature and circulation depth, on this basis, the relationship between the hydrothermal activity characteristics of hot springs near the fault and the seismic activity was investigated. The results show that the hydrochemical type of the hot springs near the Weixi-Qiaohou fault is mainly of Na-HCO3 type, which is distributed along the fault from north to south, with local differences, and the Na-SO4 and Ca-SO4 types are mainly found in the Lanping area at the northern end of the fault, and Na-SO4·HCO3, Ca-SO4·HCO3, and Na-Cl types are found in the west of the fault, changes in the chemical composition of hot springs are affected by differences in geothermal reservoir temperature, circulation depth and lithology. The intersecting areas of the Honghe fault and the Eryuan-Heqing fault on the east side of the fault, and the area of Madeng north of Qiaohou in the middle part of the fault are the two geothermal high-value areas, which presents the characteristics of low value at both ends and high value in the middle, geothermal heat sources may be linked to deep crustal rheological materials. The four M≥5.0 earthquakes all occurred in the transition stage of the high value of geothermal field across the fault to the low value of the western side of the fault, and have some correspondence with geothermal spatial distribution.

Key words: Weixi-Qiaohou fault, Hot spring, Geothermal reservoir temperature, Earthquakes, Geothermal anomaly

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