26/12/2025
" Figure 4
Cross section of a crustal column illustrating the chain of processes that form critical mineral deposits in a convergent magmatic arc setting. Each deposit type shows its main commodity and companion or by-product elements. From bottom to top, the figure shows the subducting hydrous oceanic crust that sources volatiles and ligands (water, chlorine, and sulfur) and contributes to the partial melting of the hydrated mantle, resulting in water-rich basaltic magmas (after Griffin et al. 2013, Park et al. 2021, Xu et al. 2021, Heinrich 2024). These magmas rise through the subcontinental lithospheric mantle (SCLM) and pond in the lower crust (MASH zone: melting-assimilation-storage-homogenization), where they can form metal-rich sulfide cumulates. Magmas then ascend through the crustal column to the mid-upper crust (∼10–15 km), forming large magma reservoirs, which may generate lithium pegmatite deposits (in light blue). Shallow plutons (∼3–5 km), fed by these reservoirs, may form porphyry copper and iron oxide-copper-gold (IOCG) deposits by exsolution of metal and sulfur-rich hydrothermal fluids (ore bodies shown in dark blue). Metallogenic processes can also operate on Earth's surface. For example, lithium and rare earth elements (REE) can be weathered from rocks in the surface, or sourced from volcanic fluids, and transported by surface or ground waters to form lithium-rich brines and regolith-hosted REE and lithium clay deposits (shown in dark blue)."
Source:
Martin Reich, Adam C. Simon. 2025. Critical Minerals. Annual Review Earth and Planetary Sciences. 53:141-168. https://doi.org/10.1146/annurev-earth-040523-023316
