P–T pseudosections in the model system NCKFMASHTO (whole-rock compositions expressed in mole %) and compositional isopleths for (a) the migmatitic paragneiss GDB8 and (b) the migmatitic grey gneiss SP3B. Red arrow and red star show the inferred P–T path (GDB8) and the equilibration P–T conditions (SP3B), respectively. Field limits are marked by the phase that appears/disappears. See text for details.