不同赋存环境下浙江省热水水文地球化学特征

摘要

The geothermal water in Zhejiang province can be divided into sedimentary basin type and apophysis mountain type.Bounded by the Jiangshan-Shaoxing deep fracture,the geothermal waters of different storage environment in the Northwest Zhejiang and Southeast Zhejiang have their own characteristics.In this paper,the hydrogeochemical characteristic of different geothermal water in different storage environment has been studied.The research shows that,the sedimentary basin type geothermal water in the Northwest Zhejiang is HCO3-Na(Ca) type,the water temperature is not less than 40 ℃,and belong to brackish water or salt water.The apophysis mountain type geothermal water in the Northwest Zhejiang is HCO3-Ca type,the water temperature is less than 40 ℃,and most belong to fresh water.The apophysis mountain type geothermal water in the Southeast Zhejiang is HCO3-Na (Ca) type,part of them are rich in Cl-and SO42-,the water temperature is totally higher than that in the Northwest Zhejiang,and most of them belong to fresh water.The research of δ18O and δD shows that the geothermal water in Zhejiang province are all from the atmospheric precipitation,and the Southeast Zhejiang thermal water is richer in δ18O and δD than the Northwest.The δ18O value in the geothermal water increases with the concentration of Cl-,especially in the Northwest Zhejiang sedimentary basin type thermal water,which shows that the storage Environment of the Northwest Zhejiang sedimentary basin type geothermal water is relatively more closed,and the cap layer is relatively complete and can keep heat better.Therefore,this type of geothermal water has higher water temperature and more adequate water-rock reaction than the others.%浙江省热水可分为沉积盆地型和隆起山地型两类,以江山-绍兴深大断裂为界,浙西北和浙东南热水因其赋存环境的不同而各具特色.本文通过对全省范围内的代表性地热水进行采样分析,研究省内不同类型热水的水文地球化学特征.研究表明,浙西北沉积盆地型热水以HCO3-Na(Ca)为主,水温均大于40℃,属于微戍水、戍水;浙西北隆起山地型热水以HCO3-Ca型为主,水温均小于40℃,大部分属于淡水;而浙东南隆起山地型热水则以HCO3-Na(Ca)为主,部分还富含Cl-和SO42-,整体看来水温高于浙西北隆起山地型而低于浙西北沉积盆地型,大部分也为淡水.热水δ18O和δD分析结果表明热水来源于大气降水,浙东南热水较重于浙西北,省内热水的δ18O值均随着Cl-浓度增大而增大,浙西北沉积盆地型热水的这种趋势更为明显,表明其拥有相对封闭的赋存环境,较好的盖层完整性和保温性,因而该类型热水温度较高,水岩交换反应更充分.