Precipitation mechanism of tufa in Lake Cherigele, a salt lake in the Badain Jaran Desert, NW China

Tufa serves as a significant archive for understanding the evolution of the water cycle and conducting paleoclimate research due to its abundant sedimentary information. However, the mechanisms underlying tufa precipitation at a closed salt lake in the arid Badain Jaran Desert (BJD) remain unclear. This study focuses on Lake Cherigele (CRG) as a case study and elucidates the key hydrogeochemical processes involved in tufa deposition along the lakeshores through hydrogeochemical experiments and simulations. The results indicate that (1) tufa was deposited during the middle to Late-Holocene, with U/Th ages ranging from 4216 to 594 a BP. (2) The tufa is primarily composed of calcite and aragonite crystals. (3) The precipitation mechanisms of tufa in the salt lake involve a combination of mixing between lake water and groundwater, spring degassing, and evaporation. (4) The mixing of calcareous groundwater with alkaline lake water is the predominant process for tufa precipitation; when the proportion of lake water reaches approximately 7.5%, the precipitation rate attains its maximum. In the arid climate of the Late-Holocene, the cumulative effects of these hydrogeochemical processes facilitate the continuous deposition of tufa. Our research provides hydrogeochemical evidence for tufa deposition in desert salt lakes, which can inform studies on the interactions between desert groundwater and lakes, as well as the evolution of lakes in the BJD.