四川昭觉竹核温泉水文地球化学特征及成因

四川昭觉县作为国家级贫困县,位于甘孜—新龙—理塘地热带的延伸区域内,拥有丰富的地热资源,但利用率低。为了揭示川西甘孜—新龙—理塘地热带热循环机理,助力当地的扶贫攻坚,合理开发利用地热资源,选择四川昭觉竹核温泉为研究对象,对其进行水化学和稳定同位素测试分析。结果表明:竹核温泉的水化学类型为HCO₃-Na型,补给区的温度约为14.71 ℃,补给高程为3 345~3 560 m;采用SiO₂地热温标法计算出热储平均温度为95.41 ℃,利用混合模型和硅-焓图解法估算出大温泉的混入冷水比例分别为77%、75.95%,小温泉的混入冷水比例分别为81%、78.61%,储热循环的深度范围为3 426.38~3 766.81 m;竹核温泉受木佛山断层和竹核断层等断裂带控制,在地热深循环的过程中与浅层冷水发生混合,与围岩发生水-岩反应,出露地表形成了以“大温泉、小温泉”为中心的中-低温地热资源。

Hydrogeochemical Characteristics and Genesis of Zhuhe Hot Springs in Zhaojue,Sichuan Province

Zhaojue, a national-level poverty-stricken county in Sichuan Province, is located in the extended Ganzi-Xinlong-Litang geothermal field. Revealing the geothermal heat cycling mechanism of Ganzi-Xinlong-Litang geothermal field in western Sichuan would help to alleviate local poverty and rationally develop and utilize geothermal resources. In this study, the Zhuhe hot springs in Zhaojue were analyzed for their hydrochemistry and H-O stable isotopes. The results show that the Zhuhe hot springs are HCO₃-Na-type, whilst the temperature of the supply area is about 14.71 ℃, and the supply elevation is 3,345-3,560 m. The mixing model and the silicon-enthalpy model were used to estimate the proportion of cold water mixing in large hot springs, which yielded 77.00% and 75.95%, respectively. Similar estimation yielded 81.00% and 78.61%, respectively, for small hot springs. The depths of heat storage cycle were estimated to be 3,426.38-3,766.81 m. Formation of the Zhuhe hot springs are likely controlled by the Mufoshan and Zhuhe faults. During the deep geothermal circulation, the spring water likely mixed with shallow cold water and reacted with the wallrocks. The exposed surface formed the medium-low temperature geothermal resource centered on “large hot spring and small hot spring”.