The eastern Himalayan syntaxis is the easternmost end of southern Tibet and undergoing the continental Indian-Eurasian collision. The occurrence of large amounts of geothermal waters with high temperatures along the regional active faults is a clear manifestation of an abnormal thermal structure of the crust. In order to further complement the distribution characteristics of hydrothermal activity in southern Tibet, geothermal waters were collected and the hydrochemical characteristics and genetic mechanisms were analyzed. In the eastern Himalayan syntaxis geothermal field, geothermal waters show different compositional features. The major ions are Na⁺, Ca²⁺ and HCO₃⁻, SO₄²⁻, which are mainly controlled by water-rock interaction. Two peculiar hydrochemical characteristics of geothermal waters are proposed: ⅰ) the Cl⁻ concentration of three water samples is abnormally high due to the likely contribution of magmatic water; ⅱ) the other three have a lower Cl⁻ concentration but higher temperature because of flashing steam heating. The positive correlations between B, Li and Cl concentrations indicate that the geothermal waters originate in a parent geothermal liquid. The enthalpy-chloride diagram shows that the Cl⁻ concentration and the enthalpy of the parent geothermal liquid are 283 mg/L and 1732 J/g (matching a temperature of 413.74 °C), respectively. Four cooling processes for the geothermal waters which ascend from reservoirs to surface were suggested, i.e., conductive cooling, adiabatic cooling, mixing with cold groundwater and the combination of these processes. The partial melting derived from crustal anatexis or crust-mantle mixing is the heat source for this geothermal field. The oxygen and hydrogen isotopic ratios indicate that the geothermal waters are meteorically-fed. The meteoric waters infiltrate via brittle tensional small-scale faults. According to the results of hydrochemical analysis, the evolution patterns of geothermal waters have been further summarized into seven patterns. Except for Pattern g, Patterns a to f are associated with the parent geothermal liquid.

东喜马拉雅构造界是藏南最东端，正经历印欧大陆碰撞。沿区域活动断裂出现大量高温地热水，是地壳热结构异常的明显表现。为进一步补充藏南地区热液活动的分布特征，采集地热水并分析其水化学特征和成因机制。在喜马拉雅东部构造地热田，地热水呈现出不同的组成特征。主要离子是 Na ⁺、Ca ²⁺和 HCO ₃ ^-、SO ₄ ^2-，主要受水岩相互作用控制。提出了地热水的两个独特的水化学特征： ⅰ)由于岩浆水的可能贡献，三个水样的 Cl ^-浓度异常高；ⅱ)由于闪蒸蒸汽加热，其他三个具有较低的 Cl ^-浓度但较高的温度。B、Li 和 Cl 浓度之间的正相关表明地热水起源于母地热液体。氯化焓图显示 Cl ^-母地热液体的浓度和焓分别为 283 mg/L 和 1732 J/g（匹配温度为 413.74 °C）。提出了地热水从水库上升到地表的四种冷却过程，即传导冷却、绝热冷却、与冷地下水混合以及这些过程的组合。来自地壳熔断面或壳幔混合的部分熔融是该地热场的热源。氧和氢同位素比表明地热水是由大气层供给的。大气水通过脆性张力小规模断层渗入。根据水化学分析结果，地热水演化模式进一步归纳为七种模式。除了模式 g，