Reworked staurolite-rich metamorphic belts as lithium-fertile terranes

Lithium is a strategically critical yet scarce metal vital for the global energy revolution. Understanding how lithium becomes enriched during orogenesis helps locate lithium-fertile terranes. We investigated seven Barrovian metamorphic sequences and metamorphic country rocks from eleven pegmatite-type lithium deposits/pegmatite fields. Staurolite and biotite are the primary lithium hosts (staurolite > biotite ≥ chlorite > muscovite) in metapelites, with average lithium contents increasing from distal Barrovian metamorphic rocks (426 ppm and 75 ppm) to those 200-500 meters from evolved granites (738 ppm and 149 ppm), and to metamorphic country rocks within 200 meters of lithium-rich intrusions (1395 ppm and 560 ppm). Integrated whole‑rock data and phase equilibrium modelling reveal that staurolite-rich layers with considerable biotite function as natural lithium “sponges”, sequestering lithium during metamorphism and fluid metasomatism to form fertile sources for mineralization. These findings establish staurolite‑rich terranes, reworked by multistage metamorphism and anatexis, as promising areas for lithium exploration. Staurolite-bearing layers can effectively capture lithium from crustal reworking processes, leading to the formation of enriched sources for producing lithium-rich melts during melting, according to geochemical analysis and phase equilibrium modelling of Barrovian metamorphic sequences and metamorphic country rocks.