鲜水河断裂带虾拉沱盆地断面地下水化学特征及控制因素

为研究鲜水河断裂带内地下水水化学特征及离子来源,在采集虾拉沱盆地内降水、地表水、地下水、温泉水样品的基础上,综合运用离子比值、相关性分析、Gibbs图、Piper三线图和饱和指数等方法,分析了地下水中主要离子特征,并结合氢氧同位素信息分析了地下水的补给来源.结果表明,虾拉沱盆地地下水均为弱碱性,阳离子以Ca~(2+)、Mg~(2+)和Na~+为主,Ca~(2+)占总离子2. 6%～53. 6%,平均为28. 84%,Mg~(2+)占总离子2. 7%～57%,平均为40. 6%,Na~+占总离子6. 2%～93. 1%,平均为28. 6%;阴离子以HCO_3~-为主,占总离子82. 4%～98%,平均为89. 6%,而章谷温泉主要以HCO_3~-和Na~+为主,分别占阴阳离子的93. 1%和98%,TDS介于116. 11～372. 75 mg·L~(-1),均值281. 91 mg·L~(-1);地下水水化学类型为HCO_3~-Mg·Ca和HCO_3~-Ca·Mg型,水文地球化学过程受碳酸盐岩风化溶解控制;温泉受断裂带控制明显,主要发育在鲜水河主断层附近,水化学类型为HCO_3~-Na型,水文地球化学过程受硅酸盐岩溶解控制.

Hydrochemical Characteristics and Possible Controls of Groundwater in the Xialatuo Basin Section of the Xianshui River

In order to study the characteristics of groundwater chemistry and groundwater flow system in the Xianshui River fault zone, samples of precipitation, surface water, groundwater, and hot spring samples in the Xialatuo Basin were collected and tested. Through the test data, the main ions and the sources of recharge were analyzed by means of ionic relations, correlation analysis, Gibbs plot, Piper triangular diagrams, and saturation index. The groundwater recharge sources in the basin were studied using combined hydrogen and oxygen isotope information. Results show that all the water samples in the study area were weakly alkaline. The predominant cations were Ca²⁺, Mg²⁺, and Na⁺. Among these, Ca²⁺ accounted for 2.6%-53.6%, with an average value of 28.84%, Mg²⁺ accounted for 2.7%-57%, with an average value of 40.6%, and Na⁺ accounted for 6.2%-93.1%, with an average value of 28.6%. The anions were mainly HCO₃^-, accounting for 82.4%-98% of the total anions and with an average value of 89.6%. HCO₃^- and Na⁺ accounted for most of the ions with 93.1% and 98%, respectively, in the Zhanggu hot spring. The total dissolved solids (TDS) of the groundwater ranged from 116.11 to 372.75 mg·L^-1, and with an average value of 281.91 mg·L^-1. The hydrogeochemical type of groundwater was HCO₃-Mg·Ca and HCO₃-Ca·Mg. It is controlled by carbonatite dissolution with a circulatory depth range in dozens of meters. The hot springs are controlled by the fault zone and are mainly distributed along the main stem of the Xianshui River fault. Their water is of the HCO₃-Na type. The hydrogeochemical process is controlled by silicate dissolution with a circulatory depth range in thousands of meters.