西藏谷露高温地热系统水文地球化学特征及成因模式

Hydrogeochemical characteristics and genetic model of Gulu high-temperature geothermal system in Tibet,China

通过对西藏谷露高温地热系统的热水进行水文地球化学特征分析来研究其成因模式。研究结果表明，研究区热水为中偏碱性水，矿化度较高，化学类型主要为 Cl·HCO3-Na 型和HCO3·Cl-Na 型。热水在沿主要控热断裂上升途中与围岩发生物质和能量的交换，水岩作用强烈，到达浅部之后，由于受到冷水的混合作用影响使得温度下降，在 Na-K-Mg 三角图上表现为局部成熟水和未成熟水。利用混合模型对热水未受到冷水混合影响之前的温度进行估算，得到热储的温度范围为195～260℃，冷水混入比例为52％～74％。

Through the researches on the hydro-geochemical characteristics of the thermal water in the Gulu high-temperature geothermal system,this paper studies the genetic model of the system.The result shows that the thermal water of the study area is neuter and leaning alkalinity water with high TDS and belongs to Cl·HCO3-Na type and HCO3 ·Cl-Na type.The thermal water has a deep cycle depth and exchanges matter and energy with the wall rocks during rising.Because of the mixing of cold water, the temperature of the thermal water decreases when it arrives to the shallows. Therefore,the thermal water belongs to the local mature water and immature water in the Na-K-Mg triangle diagram.The authors use the mixture model to estimate the temperature of the thermal water that is not mixed with cold water.The results show that the temperature range of the geothermal reservoir is 195~ 260℃ and the cold water mixing ratio is 52%~74%.