Representative thin section photomicrographs of the Cézarenque–Joyeuse gneisses: (a) augen gneiss with 0.5 cm-sized engulfed quartz grains embedded in a finer-grained foliated matrix with alternating layers of quartz–albite and biotite (chloritized)–muscovite; (b) close-up on the inner part of a 2 cm-sized lenticular quartz–feldspar aggregate showing the preservation of relict K-feldspar (microcline) surrounded by a fine albite (sericitized)–quartz association; (c) albite gneiss with alternating fine-grained quartz–albite and biotite (chloritized)–muscovite layers overgrown by mm-sized albite porphyroblasts; (d) leucogneiss composed of a foliated quartz, feldspar and muscovite assemblage with truncated tourmaline grains (dated sample 19CEZ54, see text and Fig. 4).