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.

Automated summary

The Dong-Xi-Taijinaier Salt Lake (DXTSL) in the Qaidam Basin is a significant lithium reserve in China, but the origin of the lithium deposits in this region is still unknown. The study investigated the hydrochemistry and lithium isotopes of water and solid samples from the Nalenggele River catchment, along with rock leaching experiments. The results showed that hot springs in the upstream had high lithium content but low 87Li values, indicating them as an important lithium source. Additionally, leaching experiments revealed that volcanic rock weathering and hot springs are the main contributors to the lithium deposits in DXTSL.