深变质岩区地热流体化学特征及成因——以滇西陇川盆地温泉为例

Chemical Characteristics and Genesis of Geothermal Fluid in Deep Metamorphic Rock Area: A Case of Hot Springs in Longchuan Basin, Western Yunnan

为了对深变质岩区地热流体的成因和演化进行深入研究,在滇西陇川盆地开展了地质、放射性测量、磁法测量、水文地质和水文地球化学等调查工作,深入分析了盆地内尺巴处温泉的水文地球化学及同位素特征。结果表明:温泉水化学类型为HCO_(3)·SO_(4)·CO_(3-)Na型,温泉中Li^(+)质量浓度为0.220mg/L,达到了锂矿泉水的命名标准,F^(-)质量浓度为8.29mg/L,可称为氟水,具医疗价值;温泉热水中冷水混入比例为0.72,热水补给高程为1166.83m,补给区温度为9.96℃,热储温度为191.71℃,循环深度为2082.29m,温泉天然放热量为9.49×10^(12) J/a;温泉水来源于大气降水,为深循环上升泉;地下水水化学组分的成因类型为岩石风化型,其主要组分来源于水岩相互作用;热源主要为深部未冷却的岩浆传导热及活动断裂产生的构造热,其次有少部分岩体中放射性同位素产生的放射热;深变质岩区温泉水中的pH值,SO_(4)^(2-)、Cl^(-)、Na^(+)、SiO_(2)质量浓度及总碱度高于冷水泉,Ca^(2+)、Mg^(2+)质量浓度低于冷水泉。

In order to study the genesis and evolution of geothermal fluids in deep metamorphic rocks,the geological,radiometric,magnetic,hydrogeological,and hydrographic geochemistry surveys were carried out,the hydrographic and isotopic characteristics of Chibachu hot spring were thoroughly analyzed,and the cause of formation and characteristics of the hot spring were studied.The results show that:The hydrochemical type of the hot spring is HCO_(3)·SO_(4)·CO_(3-)Na,the content of Li^(+) in the hot spring is 0.220mg/L,which reaches the naming standard of lithium mineral water;The F^(-) content is 8.29mg/L,which can be called fluorine water with medical value.The cold water mixing ratio in the hot spring water is 0.72,the recharge elevation of the hot water is 1166.83m,the temperature of the recharge area is 9.96℃,the thermal storage temperature is 191.71℃,the circulation depth is 2082.29m,and the natural heat release of the hot spring is 9.49×10^(12) J/a.The hot spring water comes from the atmospheric precipitation and is a deep-cycle rising spring.The genesis type of the groundwater hydro-chemical component is rock weathering,and its main component comes from water-rock interaction.The heat source is mainly the conduction heat of the deep uncooled magma and the tectonic heat produced by the active faults,and followed by the radiant heat produced by radionuclides in a small part of the rock mass.The pH,SO_(4)^(2-),Cl^(-),Na^(+),SiO_(2)and total alkalinity content of hot springs in the deep metamorphic rock area are higher than that of cold springs,but Ca^(2+)and Mg^(2+)contents are lower than that of cold springs.Currently,the hot spring is used only for bathing,and needs to be further developed and utilized.