Li content and Li-Sr-Nd isotope composition of salar deposits from southern Puna salars (Argentina)

The Central Andes of South America hosts the largest known lithium (Li) anomalies in a restricted area, but the primary lithium sources of the salar deposits and the mobilization process of lithium are still a matter of speculation. Chemical weathering at or near the surface and leaching in hydrothermal systems of the active magmatic arc are considered as the two main mechanisms of Li extraction from the source rock. The lithium and strontium isotope composition of typical salar deposits offer insights into the processes on how Li brine deposits in Andean evaporites are formed. To further the understanding of the different processes of Li mobilization (weathering and/or hydrothermal leaching) and accumulation that play an important role in the salars of the southern Puna in north-western Argentina, we study the Centenario, Ratones and Diablillos salars, the smallest salars that are among the world-class brine deposits in the Central Andes Li-rich salars. We use Sr isotopes (87Sr/86Sr) for source tracing and Li contents and Li isotopes (δ7Li) to constrain Li mobilization from source to deposition. Nd isotope compositions (143Nd/144Nd) were also determined in clastic sediment samples from salar to provide additional constrains to the rock sources. The studied materials include surface catchment and salar surface samples from the three studied closed basins (rocks, freshwater, brines, salts, travertine, siliciclastic sediments) and core samples (siliciclastic sediments and rocks) and fluid (brines) samples to a depth of 250 m, obtained from Salar de Diablillos (southern Puna in north-western Argentina).