The role of climate in the accumulation of lithium-rich brine in the Central Andes

摘要: Abstract Lithium-rich brine within the sub-surface of Salar del Hombre Muerto (SHM) salt pan in Andes northwestern Argentina has a chemical and isotopic composition which is consistent with Li derived from several sources: modern halite saturated lagoon, Li-rich salts brines formed recently, dissolution precipitated ancient saline lakes. SHM lies closed basin that includes part massive Cerro Galan caldera drained by Rio los Patos, responsible for 90% surface runoff into salar. The low isotope composition, +3.4‰, this river significant contributions geothermal spring water. As water drains through volcaniclastic deposits cover large proportion basin, removal, as indicated decreasing Li/Na, occurs but without fractionation. This indicates mechanism sorption onto smectite or ferrihydrite rather than incorporation octahedral structural sites clays. These observations suggest conditions high altitude desert have limited dilution hydrothermal well formation clay minerals, jointly allowed resource to accumulate rapidly. Changes climate on multi-millennial time scale, specifically hydrologic budget, resulted solute accumulation rates been variable time, decoupled Na fluxes. Inflow salar under Li/Na (7.9 × 10 −3 wt) δ 7 indistinguishable basement rocks (−0.3‰ +6.4‰), while pluvial lake was 40 times lower lagoon (0.1–0.3 × 10 compared 10.6–13.4 × 10 ) slightly higher Li, +6.9‰ +12.3‰, reflecting uptake 6 secondary minerals wetter climate.