THE USE OF GEOCHEMICAL INDICATOR ELEMENTS IN THE EXPLORATION FOR HOT-WATER SOURCES WITHIN GEOTHERMAL FIELDS

Soils, rocks, altered rocks, hot and cold waters, and hot spring preci pitates were sampled within and on the outskirts of geothermal fields in China. The contents of thirty trace elements in soils and rocks sho w that Hg, As, Sb, Bi, Li, Rb, Cs, Au, Ag, B, W, Sn, Pb, Zn, Mn, Ni an d Co can serve as direct and indirect indicators for geothermal field exploration. Large amounts of data indicate that Hg, As and Sb are the best indicators of hot water sources. Altered rocks contain higher Hg , As, Sb, Bi and Be than unaltered rocks. Based on their abundances in hot waters, it is suggested that the following elements may be used a s hydrochemical indicators of high-temperature hot-water geothermal sy stems: K+, Na+, Ca2+, Mg2+, SO42-, HCO3-, F-, Cl-, SiO2, HBO2, CO2, pH , total dissolved solids and hydrochemical types, as well as Hg, As, S b, Be, Li, Rb and Cs. Modem precipitates associated with hot springs h ave high contents of Ba, Be, Fe, Ti, Hg, As, Sb and Bi. Using these ge ochemical data, the authors have had much success in locating hot wate r drill sites within geothermal fields. Case histories are described f or five geothermal areas.