西藏日多温泉水化学特征及其物质来源

摘要

热泉水的水化学特征包含其形成过程中地质、构造、断裂、蚀变以及环境变化等多种信息,是研究地热流体形成和物质来源最基本和最重要的特征之一。西藏日多温泉发育于古新统典中组(E1 d )和下白垩统林布宗组(K1 l)地层。水化学特征显示：日多温泉地下热储温度为97.5℃~110.1℃之间,pH 值为中性,水化学类型为 SO 4· HCO 3-Na 型,阳离子以 Na+、Ca2+、K+为主,阴离子以 Cl-、SO 42-、HCO 3-为主,并富含HBO 2、H 2 SiO 3、F、Li、Sr、Cs、As,矿化度介于1162 mg/L~1245 mg/L 之间,符合理(医)疗热矿泉水水质标准。温泉水富含多种矿物组分的特征,与温泉水循环深度大、地下滞留时间较长(推测大于48 a)、地下热水与火山岩水-岩作用强烈有直接关系。综合研究热矿水的水化学特征,有助于更好地认识热泉水的形成过程,为热泉资源的开发利用和保护提供科学依据。%Hydrochemical characteristics of hot springs include geological,tectonic,fractured,alteration and hydro-environmental change information during the spring’s formation.So hot spring’s hydrochemistry ana-lyze is the most important and basic method for hot spring formation and material source research.The Rid-uo spring is located in Riduo,Lhasa,Tibet.It occurs in Palaeocene Dianzhong Formation (E1 d)and Lower Cretaceous Linbuzong Formation (K1 l).The hydrochemical characteristics show the spring is neutral water with SO 4 ·HCO 3 -Na.Its temperature is about 97.5-1 10.1 ℃.The positive ions are mainly Na+ ,Ca2 + , and K+ ,while the negative ones are Cl- ,SO 2 -4 ,and HCO 3 - .The degree of mineralization is about 1 1 62-1 245 mg/L,with abundant of HBO 2 ,H 2 SiO 3 ,F,Li,Sr,Cs,and As,meeting the standard of physiother-apy (medical)hot spring quality.The characteristics are directly related to the deep water cycle,long-term underground residence (presumably greater than 48 a)and intense water-rock interaction between the hot water and volcanic rock.Comprehensive study of hot spring’s hydrochemistry help to reveal the hot spring’ s formation,and benefit the recourse rational use and protection.