FLUID-MINERAL EQUILIBRIA AND SUBSURFACE TEMPERATURE EVALUATION OF

The fluid-mineral equilibrium and subsurface temperature of two selected hot spring areas in Jiangxi Province, SE-China, are analyzed on the basis of their hydrochemistry. The two geothermal fields include the Maanping Area and the Linchuan Area situated in the central part of the Province. Thermal waters of the Maanping Hot Spring Area are of the Na+K-HCO3 type, and those of the Linchuan Hot Spring Area are of Ca-HCO3 type. Solution-mineral equilibrium studies suggest that all the geothermal fluids from the two hot spring areas are departure from overall equilibrium but some minerals such as quartz, chalcedony, and calcite seem to approach equilibrium with the solution. Cation geothermometers are not applicable in such cases, while the chalcedony geothermometer is suggested as the most likely useful tool to estimate subsurface temperatures of such systems. The chalcedony geothermometer gives subsurface temperature between 70-80°C for the Maanping Area and 80-100°C for the Linchuan Area respectively. All the geothermal resources in the two areas are suitable for non-electric direct use. GENERAL BACKGROUND Jiangxi Province, SE-China, is one of the Provinces in which hot springs are most widely distributed in China. In this Province, 96 hot springs with temperatures ranging from 25 °C to 88 °C have been found. A systematic compilation of hot springs in the region was done by Li (1979), later by Sun (1988). Two hot spring areas in the Province close to Fuzho