Source Analysis of Lithium Deposit in Dong-Xi-Taijinaier Salt Lake of Qaidam Basin, Qinghai-Tibet Plateau

The Dong-Xi-Taijinaier Salt Lake (DXTSL) of Qaidam Basin is known as one of rich lith- ium reserves in China. However, the source of lithium deposits in this region remains unclear. The hy- drochemistry and lithium isotopes (87Li) of water and solid samples along the Nalenggele River catch- ment were studied in combination with rock leaching experiments. The results showed the hot springs in the upstream contained high content of lithium and ratio of Li x 1 000/total dissolved solids (1.5- 3.5), but the lower 87Li values (4.33 parts per thousand-11.59 parts per thousand), meaning that it is one important lithium sources. The leaching experiments by the rich-lithium volcanic rocks (average content of 474.7 mg/kg) showed that under temperature of 20-80 degrees C and long time duration (24-96 h), the concentration of lithium released by leaching of the sampled volcanic rocks increased from 0.58 to 1.49 mg/L, with the leaching rate de- creasing from 0.024 to 0.015 mg/(L.h) and the corresponding lithium release rate increasing from 29% to 74%. Calculation based on water-salt balance showed that the total amount of lithium contribution from hydrothermal fluids and volcanic rock weathering is about 4.99 and 0.29 Mt since 13.1 ka, respec- tively. Therefore, hot springs and leaching of volcanic rocks are main contributors to lithium deposit in DXTSL.