安徽滁河断裂带温泉水地球化学特征及其形成机理

Geochemical characteristics and formation mechanism of thermal springwater in the Chuhe fault zone in Anhui Province

滁河断裂带上发育了多个与构造活动有关的温泉,除南端的半汤温泉外,其余温泉大多热能利用不甚理想,给当地相关产业的发展带来了影响,因此有必要选取滁河断裂带上的典型温泉,从水化学特征及其形成机理上进行研究,以期为后续温泉群地热资源的合理利用及勘查方法的选择提供科学依据。据此,以滁河断裂带半汤、昭关和香泉的温泉为研究对象,分别采集了温泉水、冷井水、地表水样品,总计9个样品,完成了样品中阴阳离子、常量和微量元素25个指标的组分测试,开展了样品的氢氧同位素数值测定。通过25个指标实测数据的分析,以及氢氧同位素示踪地热水来源及受控因素研究,结果表明:3个地区的温泉水都偏向于CaSO_(4)型,均与地下水和围岩发生相互作用密切相关;半汤和昭关地区各自的温泉水、冷井水及地表水具有同源特征,地热水主要由当地降水、地表水进行直接补给,香泉地区温泉水、地表水和冷井水同源特征较弱,地下冷水径流与地热水来源不同,需要在温泉主控因素判断中引起注意;研究区玉髓温标的计算结果与采出地表热水温度接近,而石英温标的计算结果与深部的热储温度相近。研究结果初步揭示了滁河断裂带温泉水的地球化学特征,温泉水的补给关系及水岩相互作用状况,提出了该区有效的地球化学温标,有助于加深滁河断裂带温泉机理及调控因素的认识,在后续温泉功能提升和地热资源开发利用方面具有实际应用价值和研究方法示范。

Several thermal springs associated with tectonic activity occur along the Chuhe fault zone.Except for the Bantang thermal spring at the southern end,other springs along the fault zone exhibit unideal utilization of thermal energy.This affects the development of local industries.Therefore,it is necessary to delve into the geochemical characteristics and formation mechanism of typical thermal springs along the Chuhe fault zone.The purpose is to provide scientific evidence for the rational utilization and exploration methods of geothermal resources in the thermal spring groups in the future.Therefore,this study investigated thermal springs in the Bantang,Zhaoguan,and Xiangquan areas along the Chuhe fault zone,where nine samples of thermal spring water,cold well water,and surface water were collected individually.For these samples,the composition tests of 25 indices,including anions,cations,and major and trace elements,were tested,and the hydrogen and oxygen isotope values were determined.The analyses of the 25 measured indices,along with the investigation of the geothermal water source and controlling factors through hydrogen and oxygen isotope tracing,indicate that the thermal spring water in the three areas tends to be of the CaSO_(4) type and is all closely related to the interactions between groundwater and surrounding rocks.The thermal spring water,cold well water,and surface water in Bantang and Zhaoguan show consanguinity,with geothermal water being directly recharged with local precipitation and surface water.In contrast,the thermal spring water,surface water,and cold well water in the Xiangquan area show weaker consanguinity,indicating different sources for the underground cold water runoff and geothermal water.This should be noted when determining the primary factors controlling the thermal spring in this area.The temperatures calculated using a chalcedony geothermometer were close to the temperatures of the hot water recovered on the surface.In contrast,the temperatures calculated using a quartz geothermometer approached the temperatures of deep geothermal reservoirs.The results of this study preliminarily reveal the geochemical characteristics,recharge relationships,and water-rock interactions of thermal spring water in the Chuhe fault zone and propose effective geochemical geothermometers for the study area.These contribute to deeper insights into the mechanisms and controlling factors of the thermal springs along the fault zone,as well as providing practical value and a methodological model for enhancing thermal spring functionality and geothermal resource exploitation and utilization in the future.