Lower Silurian (Lower Llandoverian) sedex-type deposit and isochemical metamorphism of V/Cr-rich sediments.
Metasediments are massive anorthite layers interbedded with cherts, phosphates beds, sulfide-rich black shales, massive sulfide layers and calc-silicate beds.
Ore-bearing units form belts parallel to folds direction (NW-SE axes) (Hercynian orogeny).
V and Cr-bearing silicates are common in anorthite beds.
Sulfides (pyrrhotite and chalcopyrite) are disseminated within the metasediment layers.
V-Cr oxides, rutile and ilmenite are common in sulfide-rich shales.
Hercynian deformation and regional metamorphism are responsible for remobilization and formation of sulfide veinlets (galena, sphalerite, pyrite, chalcopyrite.).
Tardihercynian granitic intrusion and contact metamorphism induced recrystallization of previous mineralization : pd-bearing löllingite is replaced by arsenopyrite. Native palladium or PdAs2 precipitate at the interface FeAs2 / FeAsS.
Contact metamorphism of V/Cr-rich shales results in formation of metapelic hornfels with V-rich aluminosilicates and V/Cr oxides.
Ref.:
C. Canet et al. , The Canadian Mineralogist, 2003, 41, 581-595.
