福建省厦门市水热型地热系统地球化学特征及成因模式  

Geochemical characteristics and genetic model of hydro-geothermal system in Xiamen City,Fujian Province

作　　者：刘春雷[1,2] 李亚松 曹胜伟[1,2] 李剑锋 王婉丽[1,3] LIU Chunlei;LI Yasong;CAO Shengwei;LI Jianfeng;WANG Wanli(The Institute of Hydrogeology and Environmental Geology,Chinese Academy of Geological Science,Shijiazhuang 050061,Hebei,China;Fujian Provincial Key Laboratory of Water Cycling and Eco-Geological Processes,Xiamen 361000,Fujian,China;Technology Innovation Center of Geothermal&Hot Dry Rock Exploration and Development,Ministry of Natural Resources,Shijiazhuang 050061,Hebei,China)

机构地区：[1]中国地质科学院水文地质环境地质研究所,河北石家庄050061 [2]福建省水循环与生态地质过程重点实验室,福建厦门361000 [3]自然资源部地热与干热岩勘查开发技术创新中心,河北石家庄050061

出　　处：《华东地质》2023年第2期128-140,共13页East China Geology

基　　金：中国地质调查局“厦漳泉同城化地区综合地质调查(编号:1212011220944)”项目资助。

摘　　要：福建省厦门市滨海地区海水补给型地热系统虽然补给资源量很大,但是存在水质咸化、温度较低、地热水开采可能诱发海水入侵等问题,因此,查明该区地热资源成因模式,对地热资源合理开发、利用及保护具有重要意义。通过在厦门市地热田采集地热水、地下水及地表水样品,运用水化学及环境同位素分析方法,研究地热水化学特征及地热资源的成因机制。结果表明:厦门市山区及山前地带地热水的补给来源主要是山区降雨入渗,以TDS较低的HCO_(3)·SO_(4)-Ca·Na型水为主;沿海地区地热水的补给来源主要是不同程度的海水混入,以TDS较高的Cl^(-)Na型水为主。根据Cl^(-)混合模型特征,发现该区13处地热田中有10处地热田受到海水混入补给,其中浦边地热水的海水混入比达73.20%。地热水由低山区沿NW向断裂向深部运移,与区域NE向深大控热断裂交汇,接受深部传导热量后形成深部热储层,温度为185~225℃;地热水沿断裂带上升过程中有海水或地下冷水混入,混入后的浅层热储温度为80~139℃。综合分析认为,厦门沿海地区海水是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,存在两次或多次地下冷水或海水的混入,降低了地下热储温度。The seawater-recharged geothermal system in the coastal areas of Xiamen City has abundant recharge source,however,the geothermal water is always saline and low-temperature,and the exploitation of geothermal water in these areas may even incur seawater intrusion.Therefore,to ascertain the hydro-chemical characteristics and genetic mechanisms of the geothermal resources is significant for the rational exploitation and protection of these resources.In this study,the chemical and isotopic compositions of the geothermal water,cold groundwater,and surface water samples collected from a geothermal field were analyzed.The results showed that in the mountainous and the piedmont zones of Xiamen City,geothermal water is mainly recharged by the precipitation and is dominated by HCO_(3)·SO_(4)-Ca·Na water with low TDS content.By contrast,the geothermal water in the coastal areas is mainly recharged by seawater mixed to different degrees and is dominated by hydro-chemical type of Cl^(-)Na with high TDS content.Based on the characteristics of the Cl^(-)mixing model of 13 geothermal fields in Xiamen,10 geothermal fields are recharged by seawater,among which the maximum seawater mixing ratio in geothermal water is 73.20%in Pubian area.The geothermal water infiltrates in the low mountainous areas and is transported through NW-trending faults to regional deep-rooted geothermal-controlling NE faults,where the geothermal water receives the heat conducted from deeper parts.The temperature of the deep geothermal reservoirs was estimated from 185℃to 225℃.While rising along faults,geothermal water was recharged by seawater and cold groundwater,creating shallow geothermal reservoirs with temperatures from 80℃to 139℃.As indicated by the comprehensive analysis,seawater is an important recharge resource for geothermal water in the study area and significantly influenced the chemical components of the geothermal water.In addition,the geothermal water could be mixed with cold groundwater or seawater twice or more times,reducing the t

关 键 词：地热水 环境同位素 地球化学地热温标 海水补给 福建省厦门市 

分 类 号：P592[天文地球—地球化学]