Geochemical implication of the lithium content of saline spring waters in Japan

抄録

Lithium as well as major chemical constituents, and stable hydrogen and oxygen isotopic ratios in 30 saline spring waters (Cl>5, 000 mg/l) in Japan were determined to clarify the genesis of the waters. The relationship between log (Na/Li) and the temperature estimated by geothermometers revealed that the lithium content of saline spring waters are not usually controlled at the present-day temperatures of the hydrothermal systems. Taking into account the values of the deviation coefficient of lithium to seawater, C_Li = (Li/Cl) sample/(Li/Cl) seawater, and the regions from which the spring waters were collected, the spring waters can be classified into the following four groups: Group 1, representing saline waters from coastal line (C_Li = 1.2–22), Group 2 those from greentuff region (C_Li = 17–110), Group 3 those from Osaka Basin (C_Li = 160–220), and Group 4 those from the outer part of Median Tectonic Line (C_Li = 250–440). The genetic features of the respective groups are discussed in detail.