Do Geothermal systems play a role in Lithium brine enrichment in playa enviroments?

COIRA B.L.; HICKSON, C.; COOLBAUGH, M.

Salta

Simposio; 15th Quadrennial International Association on the Genesis of Ore Deposits Symposium; 2018

SEGEMAR

Exploration for economic deposits of lithium to be processed for use in batteries to power electric vehicles has become supercharged in the past few years. Numerous companies have entered the race to identify resources and many are focused on potential brine deposits within the internally drained basins that make up the Andean Puna (Altiplano) region of Argentina, Bolivia, and Chile, as well as the Basin and Range region of the western United States (Nevada and Utah in particular). It was at Albemarle?s Silver Peak mine in Clayton Valley, Nevada where the evaporation pond technology to extract lithium was developed, and where lithium values during initial phases of production were as high as 600 mg/l. In South America the concentrations in various salars varies significantly.Values range from less than 100 mg/l to over 1,500 mg/l, with a similar variability in the concentration of magnesium and other contaminants. The question remains as to why such a variability exists. In general, lithium brine depositsrequire a specific set of geological and climatological factors: 1) a source of lithium, 2) a natural extraction mechanism, 3) a transport mechanism, 4) a trap (closed basin), 5) a suitable solar evaporation rate, and 6) scale (mass flux of lithium and limited dissolved salt competition).Geothermal fluids are spatially associated with many lithium brine resources around the world (e.g., Clayton Valley, Nevada; Quaidam Basin, China; Atacama Salar, Chile; Salinas Grandes, Argentina). Thermal groundwater may contribute to more efficient and selective extraction of lithium from basin sediments and basement rocks; they may help transport the enriched fluids due to thermal upwelling; and finally provide long term mass flux that oversufficient time leads to significant endowment in basins. The basins of western Nevada have many of these prerequisites, but are dominated by clastic sediments and have relatively high subsidence and sedimentation rates.For these reasons it is likely that lithium-enriched brines are deeper than in the mature basins of South America.Since few basins in Nevada have had deep drilling, paleo-brines may remain to be discovered at depths not yet investigated by exploration companies. The variability in lithium endowment between basins in South America is likely related to the first three factors listed above ? source, extraction and transport, with additional variabilityrelated to the robustness of the geothermal systems in the various basins.