关中盆地秦岭山前地下热水的循环机理  

Circulating mechanism of geothermal fluids in the submountain region of the southern guanzhong basin

作　　者：尚海敏[1] 于进庆[1] 王文科[2] 李国敏[3] 李倩睿[2] 

机构地区：[1]铁道第三勘察设计院集团有限公司,天津300251 [2]长安大学环境科学与工程学院,陕西西安710054 [3]中国科学院地质与地球物理研究所,北京100029

出　　处：《水文地质工程地质》2015年第4期150-155,170,共7页Hydrogeology & Engineering Geology

基　　金：国家自然科学基金资助(40472131)

摘　　要：地热资源作为清洁能源在经济建设和环境保护中倍受青睐,而地下热水循环机理的研究是合理开发地热资源的前提。以关中盆地横跨山前冲积扇-黄土台塬-冲积平原三类地貌单元的典型剖面为研究对象,在地下热水野外调查的基础上通过地下热水动力场、化学场和同位素场的研究构建了关中盆地秦岭山前地下热水的循环模式：地下热水主要来自第四纪末次冰期海拔2 006~2 032 m大气降水的补给,大气降水经秦岭山前断层破碎带向下渗透进入盆地深部,在异常高的地热梯度下受热后沿着渭河北侧导水断裂带上升。从补给径流区至排泄区,地下热水径流速度由快变缓,年龄逐渐变老（从21 097 a到31 809 a）,水化学类型由HCO3—Na型向Cl—Na型过渡,水岩作用从弱到强,依次发生了溶滤作用、脱硫酸作用和去白云岩化作用,可交换岩石对地下热水18O的贡献比例依次为0%、〈10%、10%~25%。Geothermal energy as a kind of clean energy is especially popular in the economic construction and environmental protection, but geothermal energy could be rationally utilized only after its circulation mechanism is well known. This study was conducted to construct the circulation mode of geothermal water in the southern Guanzhong Basin based on the characteristics of dynamic field,geochemical field and isotopic field. Water samples from various depths were collected in the typical profile which runs through the piedmont alluvial fan,the loess platform and the river plain. All the samples were analyzed for their hydrochemical compositions and environmental isotope（2H,18 O and14C）. The results show that the aquifer recharge from meteoric waters of the last glacial period of Quaternary is characterized by the altitudes of 2006-2032 m above the mean sea level. The meteoric water percolates downwards through the piedmont faults and fractures of the Qinling Mountain,and flows upwards along the permeable zones in the Lingtong-Chang ＇an and northern Weihe River after heated by a steeper geothermal gradient. From the recharge zone to the discharge zone,water flow is slower,its ages is older（ from 21 097 a to 31 809 a）,and the hydrochemical type changes from HCO3—Na type to Cl—Na type. The degree of water-rock interaction becomes stronger along the geothermal water flow path. Dissolution,desulphidation and dolomitization correspondingly occur in sequence,and the contribution of carbonate to18 O in thegeothermal water is 0%, 10% and 10% ~ 25%,respectively.

关 键 词：循环机理 地下热水 典型剖面 关中盆地 

分 类 号：P314[天文地球—固体地球物理学] TK521[天文地球—地球物理学]