U–Pb dating of monazites by LA-ICP-MS. (a) Concordia diagram showing all analytical points for monazites from the migmatitic grey gneiss SP3B. (b) Zoom of the concordia diagram showing the two age groups at ca. 2000 and 2037 Ma in the sample SP3B. (c–f) U–Pb concordia diagrams for monazites from garnet–cordierite–sillimanite migmatitic paragneiss GDB8 (c) and metapelites SAN, MAD1A and KOU7 (d, e and f respectively). SAN: staurolite-bearing micaschist; MAD1A: garnet–sillimanite–cordierite micaschist; KOU7: garnet–staurolite-bearing micaschist.