A Study Of The Characteristics And Genesis Of Hot Springs And Mineral Spring Water To The Southwest Of The Changbai Mountain

The Changbai Mountain area is one of the areas with the most active volcanic activity since the Cenozoic in China.The basalt in the study area formed a rich spatial network of fissures,which provides certain geological conditions for the formation of hot springs and mineral springs.Especially in Jingyu County,there are more mineral springs with abundant types and excellent water quality.Based on the summary of the geological structure background and hydrogeological conditions in the area,the hydrochemical characteristics and isotopic characteristics of 13 spring samples in the southwest of the Changbai Mountain are analyzed and the formation mechanisms are discussed,and an evaluation of drinking mineral springs and medical mineral springs are also carried out.Among the water samples in the study area,only Xianrenqiao hot spring?JL1?occurs in the granite,the rest of the springs all exist in the basalt.The temperatures of the spring samples measured range between 7.9 and 68?,and the TDS,between 48.5and 1398 mg/L.The hydrochemical types are mainly of SO₄-Na,HCO₃-Na and HCO₃-Ca·Mg types.The sources of the main anions and cations in the spring samples are mainly from the dissolution of silicate and aluminosilicate minerals;the main trace elements are Si,Fe,Sr,and Li;the characteristic components are mainly F^-and H₂SiO₃,the contents of which are 0.198-7.69 mg/L and 26.83-228.9 mg/L,respectively.The?²H and?¹⁸O isotopic characteristics show that the spring samples in the study area are of meteoric origin,the recharge elevation of springs ranges between1940 and 2383.33 m,and the temperature range of recharge areas is between 0.41 and4.17?.The contour maps of?²H and?¹⁸O show that?²H and?¹⁸O in the Changbai Mountain volcanic area show an obvious isotopic island,which is obviously different from the surrounding areas and the anomalous feature is closely related to the elevation effect.The geothermal reservoir temperatures of the hot springs in the study area range between 88.29 and 147.31?.The cold water mixing ratio of the Xianrenqiao hot spring?JL1?is estimated to be 66%by the silicon enthalpy equation method,and the rest of spring samples are not mixed with cold water.The formation mechanisms of the hot springs in the study area can be summarized as:the groundwater receives recharge from precipitation in the outcropping areas and infiltrates along rock fissures,meanwhile,the groundwater may receive the lateral runoff recharge from bedrock fissure water in the surrounding mountainous areas,and then undergoes deep circulation to obtain heat from heat flow or high-temperature rock-magma,and rise to the lower surface along the faults in the form of hot springs.The formation mechanisms of the mineral springs with lower temperatures can be summarized as:the groundwater receives recharge from precipitation and the lateral runoff recharge,undergoes the long and shallow circulation,and dissolves with the surrounding basalt formations,then emerges at the lower topography in the form of mineral springs with low TDS and various trace elements.The contents of Hi₂SiO₃ in hot spring samples range between 85.05 and 228.9mg/L,and the temperatures are greater than 36?,which can be named as silicic acid water and warm mineral spring.Except for the Quanyang spring in the mineral springs,the contents of Hi₂SiO₃ in the other spring samples range between 36.66 and51.82 mg/L,which all have reached the requirement of the limit index and can be named as meta-silicic acid mineral spring.