Episodic Precipitation of Wolframite during An Orogen: The Echassières District, Variscan Belt of France

Monazite and rutile occurring in hydrothermally altered W mineralizations, the Echassières district of French Massif Central (FMC), were dated by U-Pb isotopic systematics using in-situ Laser ablation-inductively coupled plasma–quadrupole mass spectrometry (LA-ICP-MS). The resulting dates record superimposed evidence for multiple percolation mineralizing fluids same area. Cross-referencing these ages with cross-cutting relationships published geochronological data reveals a long history more than 50 Ma mineralization district. These data, integrated context Variscan belt evolution compared to other major provinces world, point an original geodynamic-metallogenic scenario. formation, probably during Devonian, quartz-vein stockwork (1st generation wolframite, called wolframite “a”; >360 Ma) porphyry magmatic arc affinity is analogous Sn-W belts Andes Nanling range China. This was affected Barrovian metamorphism, induced tectonic accretion crustal thickening, middle Carboniferous (360 350 Ma). Intrusion concealed post-collisional peraluminous Visean granite, at 333 Ma, closely followed precipitation second (termed “b”), from greisen host schist. W-fertile episode has been widely recorded central Europe, e.g. Erzgebirge, but time lag 10–15 Ma. During orogenic collapse, third characterized intrusion numerous rare-metal granites (RMG), which crystallized ~310 FMC Iberia. One these, Beauvoir granite district, led formation “c” alteration.