LAUSR

Abstract The W mineralised Early Carboniferous orthogneisses (K1 and K3 orthogneiss) in the Felbertal scheelite deposit represent a chemically evolved metagranitoid series. Some of its characteristics are high concentrations of F ( N /Ho N  = 1.93–2.81). The systematic chemical trends documented for a multitude of elements (e.g., SiO 2 , TiO 2 , P 2 O 5 , Ba, Nb, Ta) and their respective ratios (e.g., 1/TiO 2, Nb/Ta, Zr/Hf) indicate that crystal-melt fractionation controlled the evolution of the granitic melts. The higher differentiated, peraluminous light-coloured K1-K3 variety (ASI = 0.99–1.08, Nb/Ta = 5–7, Zr/Hf = 13–18) evolved from the less differentiated, metaluminous dark-coloured variety (ASI = 0.93–1.03; Nb/Ta = 6–10, Zr/Hf = 18–24). Peraluminous holo-leucocratic aplite gneiss represents the most evolved member of the series (ASI = 1.11–1.12, Nb/Ta = 4, Zr/Hf = 9–10). Modelling of magmatic differentiation assuming Rayleigh fractionation shows that c. 70–90% of the residual granitic magma had crystallised at the time of the emplacement of the aplites. When compared to barren metagranitoids in the central Tauern Window (“Zentralgneis”), the metaluminous dark-coloured K1-K3 orthogneiss shows some geochemical similarities with the peraluminous Felbertauern augengneiss, one of the regional orthogneisses exposed near the W deposit. Elevated concentrations of Nb (