Terminal lakes are important archives of continental hydroclimate and in some cases contain important economic resources. Here, we present an 2.9 m.y. lacustrine carbonate carbon and oxygen stable isotope record from a Great Basin continental drill core. We paired these measurements with bulk lithium concentrations to reveal a relationship between past climate and lithium enrichment in authigenic lacustrine clays. Further, we explored the possible effects of changing seasonality on the isotope record through the use of paired air mass trajectories and modern isotope data. Our findings show the evolution of the basin’s moisture balance over million-year time scales, which we attribute to variations in precipitation seasonality as well as fluctuations in the amount of evaporation associated with changes in atmospheric moisture convergence and divergence. We found a positive correlation between the oxygen isotope values of the lake carbonate and the bulk sediment lithium concentrations, which we argue is indicative of evapoconcentration of the lake environment and subsequent enrichment of the authigenic clays. Our results suggest a link between past hydroclimate changes and the formation of lithium-rich authigenic clays feeding high lithium concentrations in this modern brine aquifer system.

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