Collisional Orogen Dynamics Controls the Type, Timing and Location of Critical Metal Deposits

ABSTRACT The relationship between critical metal mineralisations (W, Sn, Nb, Ta, Li) and collisional orogens remains poorly understood. We combine U–Pb geochronology of metal‐carrying minerals and geochemical modelling to constrain metal mobility in the Variscan Iberian collisional orogen. Two overlapping periods of mineralisation are identified: magmatic–hydrothermal Sn–W deposits from ca. 340 to 285 Ma and rare‐metal granite (RMG) and pegmatite (RMP) Li–Sn–Nb–Ta deposits from ca. 315 to 295 Ma. We show that W‐rich fluids can be produced from metapelite‐derived anatectic melts without further differentiation, leading to their dominance over Sn (+Li–Nb–Ta) early in orogenesis. In contrast, RMG/RMP generation is favoured by transcurrent structures and melting of felsic meta‐igneous protoliths. Both features become increasingly abundant towards the end of this collisional orogen. The progression from W‐ to Sn‐dominant magmatic–hydrothermal mineralisation, followed by RMG/RMP, is a consequence of collisional orogen dynamics.