Hydrochemistry, Distribution and Formation of Lithium-Rich Brines in Salt Lakes on the Qinghai-Tibetan Plateau

Salt lakes on the Qinghai-Tibetan Plateau (QTP) are remarkable for Li-rich brines. Along with the surging demand of Li, the Li-rich brines in salt lakes on the QTP are of great importance for China's Li supply. Previous studies reported the geological, geographical, geochemical signatures of numerous salt lakes on the QTP; however, conclusive work and the internal relationships among the hydrochemistry, distribution and geological setting of Li-rich salt lakes are still inadequate. In this study, major and trace (Li, B) ionic compositions of 74 Li-rich salt lakes on the QTP were reviewed. The Li-rich brines cover various hydrochemical types (carbonate, sodium sulfate, magnesium sulfate, and chloride types) and present horizontal zoning from the southwest to the northeast along with the stronger aridity. The Li concentrations and Mg/Li ratios in these salt lakes range from 23 to 2895 mg/L, 0.0 to 1549.4, respectively. The distribution of these salt lakes is close to the major suture zones. Geothermal water is proposed to be the dominant source of Li in the investigated salt lakes, while weathering of Li-bearing sediments and igneous rocks, and brine migration provide a minor part of Li. Four factors (sufficient Li sources, arid climate, endorheic basin and time) should be considered for the formation of Li-rich brines in salt lakes on the QTP.