Abstract:

The Conghua hot spring is located to the northeast of Guangzhou. The hot spring spots occur in granites of the Yanshan Period influenced by the NEtrending Guangzhou-Conghua fault. The thermal groundwater is predominated by K⁺，Na⁺，Ca²⁺ in cations and HCO^-₃ in anions and is of Na-HCO₃ or Na·Ca-HCO₃ type. The NETPATH program is used to model the hydrogeochemical reactions along the flow path from the upstream water sample to the hot spring site. The results indicate that the individual springs in the study area have close chemical characteristics with each other and the geothermal groundwater has undergone similar hydrogeochemical reactions. Mass transfers of the reactions from the “initial wells” to the “final wells” are relatively low. The net reaction results of the minerals along the path include precipitation of potash feldspar, kaolinite, hematite and fluorite, dissolution of carbon dioxide, plagioclase and biotite. Silicon dioxide behaves differently in different courses and ion exchanges of Ca²⁺/Na⁺，Mg²⁺/Na⁺ may occur in the courses.

Key words: hot spring, NETPATH, hydrogeochemical modeling, Conghua, Guangdong