Understanding the spatial variation in lithium concentration of high Andean Salars using diagnostic factors

Abstract

Salars (basins of internal drainage) in the “Lithium Triangle” countries (Argentina, Bolivia, Chile) hold >50 % of the global lithium resources within lithium-rich brines. Given the imperative for lithium production to enable the energy transition and that salars by their very nature are highly variable, so a framework to both characterise their differences as well as identifying their similarities would be beneficial to understanding their provenance and potential for exploitation.In this study, data for 29 salars based on environmental factors: rainfall, evaporation as well as their physical characteristic: pan size and basin size have been used to characterise them along with those describing their setting land-use/cover and geological outcrop. These parameters have been normalised by creating a ratio of the lithium concentration divided by the factor for each salar. Cross-correlation has been used to develop relationships between these normalised factors, combined with principal component analysis to identify clustering and to further characterise groupings of behaviours.Two such relationships emerge out of this process: regional and local. Regional covers factors such as elevation, precipitation, and evaporation; local includes size of watershed, salar nucleus, land cover and geological outcrop in the watershed. However, Salar de Atacama is identified as an outlier and so the transferability of the understanding of its provenance and operation must be treated with caution. Other salars could be added to the framework as more information becomes available. The methodology presented here could help exploration by characterising salars into categories as their smaller size may not necessarily mean lower lithium mass. Further, such a framework can inform policy decisions and instruments by recognising the complexity of salars combined with the need to understand the environmental impacts of brine extraction.