Supplementary material

SM1: EMP analyses in monazite (wt.% and cationic formula for 4 O)

SM2: Th-U/Pb isotopic data of monazite and xenotime

SM3: Trace element analyses of monazite from the sample VP7-2

SM4: Analytical methods

SM5: X-ray element maps of monazite crystals. The maps were acquired at the EPMA by wavelength dispersive spectrometry of Ce (Lα line), Gd (Lβ line), Th (Mα line) and Y (Lα line). Monazite crystals VP7C-40, VP7C-45, VP7-2-12 (all from paragneiss) are pristine monazite (Mnz I) isolated in garnet (Grt I) or quartz (Qz), showing in some cases Th-rich inherited nuclei (VP7C-45, VP7-2-12). Monazite crystals VP7-2-3, VP7-2-7 (from paragneiss), VP7r-1 and VP7r-8 (from orthogneiss) reacted with the hosting plagioclase (ps Pl) to form a Mnz II-bearing corona around a core of preserved Mnz I. Monazite II commonly shows enrichment in Th and Y relative to Mnz I (VP7r-1 and VP7r-8). See also Figures 3e (VP7-2-12), 3a (VP7-2-3), 4a (VP7r-1), 4c (VP7r-8).

© V. Bosse et al., Published by EDP Sciences 2024