云南省云县大控蚌温泉的特征及成因

Characteristics and formation of the Dakongbang hot spring in Yun county of Yunnan

大控蚌温泉位于云南省云县,地处滇藏地热带。温泉区附近断裂发育,主要的热储层岩性为临沧花岗岩。泉水共有五个主要泉眼,水温88.3~96℃。地下热水中主要阳离子为K+、Na^+、Ca^2+和Mg^2+,主要阴离子为Cl^-、SO4^2-和HCO3-,水化学类型为HCO3-Na型;热水矿化度0.625~0.702g/L,pH值为6.7~9,偏硅酸含量为161.1~261mg/L,F^-含量为5.85~16.1mg/L。根据δ2 H和δ18 O稳定同位素分析得知温泉水源为大气降水;估算出热水补给高程约为1800m;估算补给区温度约为3.6~7.2℃;热储温度约为143~181℃;循环深度约为2858~3496m。综合分析得出大控蚌温泉成因模式为大气降水在周围山区补给区入渗补给,地下水向深大断裂带汇集,在经历深循环过程获得深部热流加热后沿导水断裂带上涌,在上升的过程中与浅部冷水发生混合,最终以高温沸泉和喷泉出露地表。

Located in Yun county of Yunnan,Dakongbang hot spring lies in the Yunnan-Tibet geothermal belt.In the hot spring area,the geothermal reservoir is mainly composed of the Lincang Granite with well-developed fractures.There are five spring orifices with water temperature ranging from 88.3 to 96℃.Most of the cations in the hot water are K^+,Na^+,Ca^2+and Mg^2+,and most of the anions are Cl^-,SO4^2-and HCO^3-.The hot water is characterized by HCO^3-Na type in hydrochemistry,and TDS0.625~0.702 g/L,pH 6.7~9,H2 SiO3161.1~261 mg/L and F-5.85~16.1 mg/L.According to analysis of stable isotope,theδ2 H andδ18 O contents of the hot water samples indicate that the hot spring originates from precipitation.The elevation of the recharge area is estimated at 1800 m.Temperature of recharge area is about 3.6~7.2℃,and that of geothermal reservoir 143~181℃.The circulation depths of the thermal groundwater are approximately 2858~3496 m.The formation of the hot spring can be summarized as that recharging by precipitation in the surrounding mountain areas,the groundwater flows to deep and large fractures,heated by heat flows during deep circulation,then upwells as geothermal water along the fracture zones and finally crops out after mixing with cold shallow groundwater as boiling springs and fountains of high temperature.