西藏日喀则市查孜地热田水化学及同位素特征研究

查孜地热田位于青藏高原西南部。通过野外地质调查及地热钻孔揭露,发现该地热田具有较好的地热资源开发潜力。对该地热田地下热水的水文地球化学及同位素特征开展研究,发现地下热水为HCO₃-Na型; 热水与冷水的离子浓度存在差异,显示二者具有不同的物质来源,但又具有一定的水力联系。热水中的δD和δ¹⁸O同位素特征表明: 该地热田地下热水的主要补给来源为大气降水和冰雪融水,补给海拔为5 652 m以上; 大气降水和冰雪融水下渗并与沿断裂破碎带向上运移的地热流体混合后形成地下热水。断裂破碎带不仅是温泉的主要通道,也是地热流体的储集场所,地热田热水在地下运移滞留至少41 a。据SiO₂地热温标估算得出,该区地下热储温度为148.18 ~153.49 ℃,天然放热量为2 264.33×10¹² J/a。

Hydrochemical and isotopic characteristics of Chazi geothermal field in Shigatse in Tibet

Chazi geothermal field is located in Southwestern Tibetan Plateau. The geothermal potential has been ascertained by field survey and geothermal drilling. The hydrogeochemical characteristics and isotopic composition of this geothermal field show that the underground water belongs to HCO₃-Na. The difference of ion concentration between hot water and cold water shows that they have different material sources and certain hydraulic relations. The isotope analysis of δD and δ¹⁸O determines that the major source of the geothermal water in this area is meteoric water and water melt from the mountains snow and ice with the height above 5 652 m. The geothermal water was the result of the mixture of deep infiltrated meteoric water and deep-source fluid when they move along the fracture zone. The fracture zone is the main channel of hot spring and the reservoir of geothermal fluid. The migration retention time of the geothermal water in this geothermal field was at least 41 years. According to the calculated temperature of SiO₂ geothermometer, the geothermal temperature of the underground heat reservoir is about 148.18~153.49 ℃, and natural heat discharge is 2 264.33×10¹² J/a.