Study on the Distribution Characteristics of Rubidium and Cesium Elements and Their Associated Relationship with Lithium, Boron and Potassium in Brine of the Dabxun Salt Lake, Qaidam Basin

Determining the distribution characteristics of rubidium (Rb) and cesium (Cs) in salt lake brines and their associations with lithium (Li), boron (B) and potassium (K) can facilitate the gradient development and comprehensive, efficient utilization of diverse resource elements by salt lake enterprises. While research on the distribution features and source-sink processes of Li, B and K in the Qaidam Basin’s salt lakes is well-established, their paragenetic coupling relationships with Rb and Cs have not been systematically analyzed, and the geochemical mechanisms controlling Rb-Cs enrichment and their coupling with associated elements remain unclear. To address this gap, this study focuses on the Dabuxun Salt Lake in the central Qaidam Basin. Element content and H-O isotope analyses were conducted on 8 surface brine samples and 11 intercrystalline brine samples, to clarify Rb-Cs distribution characteristics and reveal their paragenetic coupling relationships and related geochemical mechanisms with Li, B and K. The results are as follows: (1) Rb and Cs are relatively enriched in the brines of Dabuxun Salt Lake, with higher average concentrations in intercrystalline brines (Rb 3312 μg/L, Cs 63.7 μg/L) than in surface brines (Rb 1352 μg/L, Cs 30.6 μg/L). (2) Both surface and intercrystalline brines show spatial distribution heterogeneity, and their paragenetic associations with Li, B and K also vary. Similar metallogenic material sources, evaporation and water-rock interaction are the key factors driving the strong paragenetic relationships (correlation coefficients ＞0.6) between Rb-Cs and Li-B-K in surface brines. (3) The negative correlation between Rb-Cs and Li in intercrystalline brines is controlled by evaporation and clay adsorption; the positive correlation with K is governed by evaporation and water-rock interaction; and the association with B is jointly constrained by evaporation, water-rock interaction and clay adsorption. This study systematically analyzes the distribution characteristics of Rb-Cs and their paragenetic relationships with Li, B and K in the Dabuxun section of Qarhan Salt Lake, providing a scientific basis for the exploration and development of salt lake resources in the Qaidam Basin.