Structural controls on lithium-bearing fluid flow in Clayton Valley, Nevada

Lithium brine systems are critical resources for the energy transition, yet the mechanisms governing lithium mobilization, transport, and concentration remain poorly constrained. In particular, the role of fault and fracture networks in controlling fluid flow and associated lithium distribution is not well resolved. New analyses of calcite-mineralized faults and opening-mode fractures, and paleo-spring deposits from Clayton Valley, Nevada are interpreted to record lithium-bearing fluid flow through > 10 Myr of Basin and Range extension. Calcite U–Pb ages related to Basin and Range extension range from 15.4 ± 6.4 to 4.2 ± 2.3 Ma. Clumped-isotope formation temperatures of vein calcites span 24.6 ± 4.1 to 139.2 ± 12.6 °C, and bulk lithium concentrations of veins and paleo-spring deposits span < 2 to 460 ppm. These results indicate that fault and fracture networks repeatedly served as conduits for lithium-bearing fluids through basement, along basin margins, and within basin-fill strata throughout basin evolution. Lithium concentrations vary systematically with host setting, with the highest values recorded in basin-fill-hosted veins and spring deposits and generally lower values in basement-hosted and basin-bounding fault veins. Several veins containing measurable lithium yield U–Pb ages older than the ∼ 6 Ma Rhyolite Ridge tuff, the dominant volcanic lithium source unit in the region, suggesting that structurally focused lithium-bearing fluid circulation locally predated its emplacement. The highest lithium concentrations, however, are generally associated with younger veins that postdate the tuff. Temperature and stable isotope constraints indicate dominantly meteoric fluids advected to depth and focused along faults, suggesting that lithium transport and enrichment in Clayton Valley does not necessarily require ascent of lithium-enriched magmatic fluids along deeply rooted crustal-scale faults. Although fault-controlled lithium enrichment has been recognized previously, this study provides direct evidence for long-lived structurally focused fluid flow associated with lithium transport over multi-Myr timescales.