Stable Isotopes (Li, O, H) Combined with Brine Chemistry: Powerful Tracers for Li Origins in Salar Deposits from the Puna Region, Argentina

Future improving of the innovative technology of Lithium air batteries correlates with an increased demand for Li-resources. We analyzed and compared stable isotopic compositions from 4 Argentinean Li rich salars. The Pozuelos (PS), Centenario (CN), Ratones (RT) and Hombre Muerte (HM) belong to the world class brine resources of the Atacama triangle. CN has a halite core surrounded by fine grained clastic sediments, while RT comprises lesser evaporates, but coarser grained volcanoclastics. Two Cl-Na SO4 brine aquifers (down to 250 m depth) host several hundreds of mg/l of Li. The surface waters are characterized by Li < 7 mg/l, δ7Li of ≈ 9.5, δD: -66 ‰ and δ18OSMOW: -7.8 ‰. The stable isotopic composition differs slightly from the upper aquifer (δ7Li ≈9.2 ‰, δD -47.2 ‰ and δ18OSMOW -0.8 ‰) to the lower aquifer (δ7Li: 9.7 ‰, δD: -51.6 ‰ and δ18OSMOW: -1.7 ‰). The dominant source of Li is related to water–rock interactions (surface, saline waters with andesites, pegmatites, pyroclastics). The comparison of our RT and CN data to those of the close-by PS and HM, shows that each salars has its own geological, hydrological and climate history which can be defined by crossing isotope tracers. However, the development of pertinent isotopic regional and local exploration proxies, needs identical data sets on systematically defined samples of the same aquifer type, on country rocks and minerals.