河北省张北县新生代玄武岩偏硅酸矿泉水化学特征及成因

Hydrochemical characteristics and formation mechanism of metasilicate mineral water in a Cenozoic basaltic aquifer in Zhangbei county,Hebei Province

【研究目的】河北省坝上地区新生代玄武岩地层蕴含着丰富的偏硅酸矿泉水资源,研究其形成机制及水岩作用对区内水资源合理利用以及发展矿泉水产业具有重要的现实意义。【研究方法】通过系统采集研究区地下水、雨水等环境水化学样品,运用数理统计、离子比值分析、同位素分析等方法,对区内新生代玄武岩偏硅酸矿泉水的形成机制进行了分析。【研究结论】张北县偏硅酸矿泉水主要分布在县域南部坝头一带的地下水补给区,以低矿化度的HCO_(3)-Ca·Mg型与HCO_(3)-Na·Mg型水为主,地下水中偏硅酸主要来源于玄武岩中钠长石、斜长石、橄榄石等硅酸盐矿物的水解,同时受到溶滤作用和阳离子交换作用的影响;氢氧同位素分析结果显示,当地地下水主要补给来源为当地夏季降水,地下水可视年龄在15~60 a。【结论】河北省坝上地区偏硅酸矿泉水的形成与当地特殊玄武岩地质构造以及特定的水文地球化学过程有关。

This paper is the result of hydrogeological survey engineering.[Objective]Metasilicate mineral groundwater is widely distributed in cenozoic basaltic stratum of Bashang area.It is of great practical significance to study the formation mechanism and water-rock interaction for rational utilization of water resources and development of mineral water industry in this area.[Methods]The formation mechanism of metasilicate mineral groundwater in Cenozoic basalt in the research area was analyzed by collecting environmental hydrochemical samples such as groundwater and rainwater systematically and using mathematical statistics,ion ratio analysis,isotope analysis and other methods.[Results]The metasilicate mineral water is mainly distributed in the groundwater recharge area of the front edge in the Bashang area on southern part of the county;And the mineral groundwater of study area is characterized by low mineralization while the main hydrochemical types of groundwater are HCO_(3)-Ca·Mg and HCO_(3)-Na·Ca;Also,metasilicic acid in groundwater originates from the hydrolysis of sodaclase,plagioclase,olivine and other silicate mineral in basalt,and is affected by rock mineral leaching as well as hydrochemical parameters cation exchange.According to the analytical results of hydrogen-oxygen isotope,it is concluded that the main source of groundwater recharge is local precipitation in summer,and the actual age of groundwater is between 15 a and 60 a.[Conclusions]The formation of metasilicate mineral water in Bashang area of Hebei Province is related to the local special basalt geological structure and specific hydrogeochemical process.