Paleoclimate controls on lithium enrichment in Great Basin Pliocene-Pleistocene lacustrine clays

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 re- lationship 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 trajec- tories and modern isotope data. Our find- ings show the evolution of the basin's mois- ture balance over million-year time scales, which we attribute to variations in precipi- tation seasonality as well as fluctuations in the amount of evaporation associated with changes in atmospheric moisture conver- gence 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 re- sults suggest a link between past hydrocli- mate changes and the formation of lithium- rich authigenic clays feeding high lithium concentrations in this modern brine aquifer system.