This preliminary work illustrates the chemical composition of sphene from Variscan tonalites with
sphene-centered ocellar texture (Ribadelago pluton, NW Iberian Massif). The ocellar texture is linked with
the percolation of a tardimagmatic melt, with trondhjemitic affinities, through an hyperdense crystal mush.
Chemical zoning in sphene, revealed by BSE imaging, shows a heterogeneous distribution of heavy trace
elements (Nb, Y, Ce and Zr) that depicts concentric, oscillatory, sector and patchy patterns. Application of
the Zr-in-sphene thermometer yields a temperature range of 746 to 778 ºC for the crystallization of
sphene in the tardimagmatic melt. It also constitutes a minimum temperature estimation for biotite partial
destabilization in this lithology