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.

Potash plays an important role in agricultural production. The Qaidam Basin (QB) in western China is a typical inland evaporite basin, which contains an abundance of K-rich brines, including shallow brines (i.e., surface brines and intercrystalline brines) in salt lakes and deep brines (i.e., pore brines and oilfield brines) in the strata. Significant studies on these brines have been reported; however, the integrated studies on sources of K, its distribution, and the sedimentary pattern of the two brine types are still inadequate. In this study, the K⁺ concentrations of sixty-four intercrystalline brines from the Qarhan Salt Lake (QSL), the largest playa in the QB, are presented. After combining those results with the major ionic compositions of river waters and deep K-rich brines, and the K⁺ concentrations of shallow brines in the QB, we concluded that: (1) The K of brines in the QSL is mainly from the high–flux K input by rivers which gain K from silicate weathering, while the “ancient Qaidam Lake” contributed little K to the QSL; (2) the large K flux supplied by rivers, the appropriate concentration degree, and the mixing of river waters and spring waters, cooperatively account for the highest K concentrations of brines in the QSL in the QB. The different river K recharges in different sections and isolated depressions are responsible for uneven K⁺ concentrations of brines in the QSL. (3) The deep brines are mainly distributed in the western QB. The K source of pore brines is from the interaction of pore water with the overlying evaporite layer. While the K in oilfield brines may be meteoric water, salt dissolution, the mixing of hydrothermal fluids, and the conversion of clay minerals to K-feldspar may consume K in the oilfield brines.

The safety of lake ecosystems on the Qinghai-Tibet Plateau (QTP) has attracted increasing attention, owing to its unique location and ecological vulnerability. Previous studies have shown that the aquatic systems on the QTP have been polluted to varying degrees by trace elements. However, little is known of the distribution and sources of trace elements in lakes in the northeast QTP. Here, 57 sediment samples were collected from six lakes (Dasugan Lake, Xiaoqaidam Lake, Kreuk Lake, Toson Lake, Gahai Lake and Xiligou Lake) in the Qaidam Basin, northeast QTP, and the trace elements (V, Cr, Ni, Cu, Zn, As, Ba, Tl, Cd, Pb, and U) were analyzed. The results indicated that Ba, Zn, V, and Cr had a higher content and a wider distribution relative to the other tested elements. Correlation coefficient matrix results showed that the trace elements in the study area were strongly correlated, revealing their source of similarity. Self-organizing maps (SOM, an artificial neural network algorithm) results indicated that the degree of pollution in Xiaoqaidam Lake was the highest, and that of Dasugan Lake was the lowest. Furthermore, all sampling points were clustered into four categories through K-means clustering. The positive matrix factorization (PMF) results indicated that atmospheric deposition and anthropogenic inputs were the main trace elements sources in these lakes, followed by traffic emission and geological sources. Collectively, trace elements of six lakes in Qinghai-Tibet Plateau presented high-content and pollution characteristics. This research provides a scientific basis for better water environment management and ecological protection on the QTP.

青藏高原是世界上地热资源最为丰富的地区之一，发育了600余处地热点，其中部分温泉和泥火山水异常富集K、B、Li、Rb和Cs等关键资源元素。文章聚焦青藏高原地热水资源元素分布特征及其来源，对西藏南部、羌塘盆地、布喀达坂峰、大柴旦、共和盆地五个主要地热区的地热水进行系统研究。结果表明：各区地热水体中K、B、Li、Rb和Cs分布特征存在显著差异，布喀达坂峰热泉的K、B、Li、Rb和Cs含量最高，其次为西藏南部地热水，而羌塘盆地、大柴旦和共和盆地的资源元素含量较低。相关性分析表明，青藏高原地热水中K、B、Li、Rb和Cs具有相似的来源，元素的富集主要受到深部地热活动的控制。此外，高分异残余岩浆流体的补给和高温水岩反应被认为是控制资源元素富集的重要途径，特别是在布喀达坂峰和西藏南部等地区。该研究对深入认识青藏高原水热活动成因及其关键资源元素富集机制具有重要的指示意义。

钾盐是我国急缺的大宗矿产之一，积极建立海外钾肥生产基地是我国钾肥安全保供的重要举措。下刚果盆地钾盐资源储量丰富，品质优良，系统梳理该钾盐矿的成矿条件研究进展有助于充分认识其成矿规律和研判其成矿潜力，进而为我国开发该地钾盐提供重要理论指导和占得先机的条件。文章基于时空维度下“源、运、储、变、保”的钾盐成矿系统理论架构，对下刚果盆地钾盐矿床的区域构造、成矿时代、物质来源、迁移搬运、储藏富集、气候条件及成矿模式等进行了总结分析，阐明了各子系统的研究进展与存在争议，提出应加强成矿物源与富集过程的量化研究，多指标约束成矿时代与迁移演化路径；同时，进行了下刚果盆地与南美同时代钾盐矿成矿条件的对比分析，强调开展区域综合研究的重要性。文章对全面构建下刚果盆地钾盐成矿系统及其后续综合开发利用具有重要战略意义。