Hydrogeochemical and Geothermal Characteristics of Hot Springs in Kilju-Myongchon Region, DPRK

Kilju-Myongchon region in DPRK, a rift valley-type basin with deep fractural structure, contains many hot springs. 45 water samples were taken from 18 hot springs in the region and hydrogeochemical analysis was conducted to investigate the hydrogeochemical and geothermal characteristics of them. The temperatures of hot springs varied from 26 to 84°C and the total dissolved solids (TDS) were mostly lower than 1.5 g/L. All hot springs except for the KM hot spring (Na–Cl–SO4 type) had Na–HCO3 type and the pH values were between 7.2 and 9.2. The hydrogeochemical characteristics was evaluated using various methods such as bivariate plot, Langelier-Ludwig diagram and Chloro-alkaline index. It is found out that these springs have been influenced by the dissolution of alkali feldspar and ion exchange reaction with country rocks. In addition, the reservoir temperatures were estimated by adopting classical geothermometry and multicomponent mineral equilibrium (MME) analysis based on water chemistry. The results provide new insights into hydrogeochemical characteristics and formation mechanism of hot springs in the region.