Linking modern-paleo lake systems: climate-driven Li-B differentiation and paleolake evolution validation in Tibetan Plateau salt lakes

• 1 Climate change drives Li and B resources evolution in Laguo Co. • 2 Increased hydrological recharge promotes B release from carbonate clay and borate. • 3 Carbonate clay retention Li constrains climate-driven Li release. • 4 Annual dynamics reveal millennial-scale hydrological-resource impacts on Laguo Co. • 5 Hydrochemistry-isotopic decode divergence in Laguo Co and it’s cogenetic lakes. Salt lake lithium (Li) and boron (B) deposits on the Tibetan Plateau, a global salt lake hotspot hosting China’s largest Li reserves and major B resources, are critical for new energy and industrial applications. This study diagnoses climate-driven decades scale source variations in Laguo Co through coupled hydrochemistry and δ 11 B-δ 7 Li isotopes, which dictate its spatiotemporal Li-B distribution. Building on these decadal diagnostics, we integrate paleolake evolution with millennial source-transport-sink processes to reveal causal linkages between mineralization sources and paleolake residues, while comparative analysis further identifies key divergence mechanisms within the homologous salt lake system. Key findings include: (1) Under warming-wetting climate-induced hydrological changes, Laguo Co brines show declining Li-B grades, Li/TDS ratios but rising B/TDS ratios. The former reflects dilution dominance, while the latter arises from competition between dilution and enhanced B recharge fluxes within the catchment–salt lake systems; (2) Sustained warm-wet conditions trigger variations in weathering fluxes, resulting in an annual increase in dissolved riverine B flux (released from carbonate clays) alongside a decrease in Li flux (retained within clays); (3) Similar hydrochemical–δ 11 B-δ 7 Li signatures between Laguo Co and Jibu Chaka salt lakes support their common paleolake origin. Their differences can be explained by distinct recharge processes occurring at millennial scales, based on the impacts of decades scale hydrological changes on hydrochemistry of Laguo Co. Specifically, the hydrochemical and δ 11 B-δ 7 Li contrasts between Laguo Co and Jibu Chaka stem from their independent source–transport–sink systems altering paleolake water evolution; (4) A pioneering validation framework tests the paleolake fragmentation and inheritance hypothesis by resolving hydrochemical divergences through contemporary source-transport-sink controls: source solutes, catchment lithology, and sink mineral sequences. This study provides valuable insights into both the impacts of climate change on salt lake resources and genetic connection between mineralizing sources and paleolake residues in salt lake deposits.