Fig. 1: Distribution of global lithium deposits and conceptual cartoon describing Li cycling in subduction zones.
a Map of continental brine, clay, pegmatite (hard rock), geothermal, and oilfield brine deposits based on compilations in this study (see Supplementary Dataset 1). Continental Li brines are dominantly found in Cenozoic/Mesozoic orogenic belts; pegmatites are found in eroded magmatic orogens (maps based on Roberts and Bally59). Base map was processed with GeoMapApp (http://www.geomapapp.org)60. b Map of estimated Li resources with size of symbols reflecting ktons of Li metal. c Map of Li reserves with symbol size corresponding to ktons of Li metal. Resources represent the amount of available Li, whereas reserves represent that which can be extracted economically. Data are based on company reports compiled in this study (see Supplementary Dataset 1). d Conceptual model for Li cycling in subduction zones. Relative to background mid-ocean ridge basaltic volcanism, Li concentrations are enhanced in arc magmas by direct contributions from the subducting slab, melting in the mantle wedge, and fractional crystallization in the upper plate. Crystal fractionation is more extensive in thick continental arcs. In addition, mature continental arcs are often associated with net-evaporative intermontane basins. Weathering of andesitic and rhyolitic source rocks in thick continental arcs, followed by transport of solutes into these local basins, leads to further enrichment of Li. In island arcs, appropriate source rocks are scarce and any mobilized Li is likely lost to the ocean.
