Geochemical characteristics and formation mechanism of thermal spring water in the Chuhe fault zone in Anhui Province
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,Zha-oguan,and Xiangquan areas along the Chuhe fault zone,where nine samples of thermal spring water,cold well water,and surface wa-ter 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 CaSO4 type and is all closely related to the interactions between groundwa-ter 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 wa-ter 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 sur-face.In contrast,the temperatures calculated using a quartz geothermometer approached the temperatures of deep geothermal reser-voirs.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.
Chuhe fault zonethermal springhydrochemistryformation mechanismgeothermal reservoir temperature
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