Fig. 4

Back-scattered electron (BSE) images illustrating the relationships between allanite, monazite and other REE-minerals. a Allanite sheaves overgrow partly resorbed monazite grains in a garnet from the Vidolm Nappe; b allanite from the Vidolm Nappe surrounded by “satellite” monazite grains (Finger et al. 2016); c, d in situ breakdown of allanite inclusions in garnet porphyroblasts from the Baia de Arieş Nappe. Allanite is partially (around the rims) replaced by monazite and xenotime; e allanite and synchysite (Y-Ce carbonates) form coronas around monazite grains in western parts of the Baia de Arieş Nappe; f monazite relics in the Biharia Nappe surrounded by an allanite halo with satellite monazite grains. Two samples from the Codru Unit exhibit g rhabdophane (Rhb*) intergrown with zoned xenotime and h allanite coronas around monazite grains. i Monazite relics in the Bretila Unit are corroded by rhabdophane (see insert), then overgrown by apatite and allanite; epidote and allanite aggregates form porphyroblasts along the foliation