摘要
海水补给型地热系统具有补给资源量大,但温度低、水质咸化等特点,查明沿海地热水循环补给条件和成因机制,对东南沿海地热资源的合理开发利用和保护具有重要意义。在泉州官桥盐田地热区分别采集了地热水、地下水和海水样品14个,利用水化学同位素特征分析和地球化学温标法,揭示了官桥盐田地热水循环补给和地热资源成因机制。结果表明:地热水水化学类型为Cl—Na型水,与海水水化学类型一致;H01和H02的溶解性固体总量(TDS)分别为2610 mg/L和3090 mg/L,地下水以TDS小于400 mg/L的HCO3—Na型水为主;地热水富集Br-,地下水中Br-未检测,表明盐田地热水存在现代海水或者海相沉积层古海水补给。根据盐田地热田H01和H02地热水Cl-混合模型计算,地热水H01海水混入比为9.13%,H02海水混入比为10.76%,显示H01在出露于第四系地层后混入了更多的地下水。综合分析认为,海水是盐田地热水的重要补给资源,地热水化学组分受海水混合作用影响明显,深层热水上升过程中存在两次或者多次地下水或者海水混入从而形成浅层热储,采用SiO2地热温标和多矿物平衡法估算的浅层热储温度在89~121°C之间。
Seawater-recharged geothermal systems are characterized by abundant recharge,low temperature and salinization.Ascertaining the circulation recharge conditions and genetic mechanisms of geothermal water in coastal areas of southeast China is of important significance in the rational exploration,utilization and protection of geothermal resources in these areas.In this study,14 samples of geothermal water,groundwater and seawater are collected from the Yantian geothermal field near Guanqiao Town in Fujian Province,China and the hydrochemical and isotopic characteristics are analyzed.The circulation recharge of the geothermal water and the genetic mechanisms of the geothermal resources in the geothermal field are revealed using geothermometers.The results show that hydrochemical type of the geothermal water in the Yantian geothermal field is of Cl—Na type,which is similar to that of the seawater.Total dissolved solids of geothermal water samples H01 and H02 are2610 mg/L and 3090 mg/L,respectively.By contrast,the groundwater in the geothermal field is dominated by the HCO3—Na type,and the groundwater samples have TDS of less than 400 mg/L.Moreover,the geothermal water is rich in Br-,which is not detected in the groundwater.These results indicate that modern seawater or ancient seawater in marine sedimentary layers is a recharge source of the geothermal water.As shown by the results of H01 and H02 calculated using the Cl-mixing model,geothermal water samples H01 and H02 have seawater mixing ratios of 9.13%and 10.76%,respectively,and H01 is mixed with more groundwater after being exposed to Quaternary sediments.The comprehensive analyses show that the geothermal water in the Yantian geothermal field is primarily recharged by seawater and its chemical composition is significantly affected by seawater mixing.Furthermore,the comprehensive analyses also suggest that the deep geothermal water is mixed with groundwater or seawater twice or more times as it rises upward,thus forming shallow geothermal reservoirs with a temperature of 89°C to 121°C,as estimated by using the SiO2 geothermometer and the multi-mineral equilibrium method.
作者
刘春雷
李亚松
洪炳义
曹胜伟
王婉丽
李剑锋
LIU Chunlei;LI Yasong;HONG Bingyi;CAO Shengwei;WANG Wanli;LI Jianfeng(Institute of Hydrogeology and Environmental Geology,Chinese Academy of Geological Science,Shijiazhuang,Hebei 050061,China;Fujian Provincial Key Laboratory of Water Cycling and Eco-Geological Processes,Xiamen,Fujian 361021,China;Southeastern Fujian Geological Brigade,Quanzhou,Fujian 362000,China)
出处
《水文地质工程地质》
CAS
CSCD
北大核心
2023年第1期158-167,共10页
Hydrogeology & Engineering Geology
基金
中国地质调查局地质调查项目(DD20190303
DD20221773)。
关键词
地热水
水文地球化学
环境同位素
地球化学温标
海水补给
geothermal water
hydrogeochemistry
environmental isotope
geothermometer
seawater recharge
