Figure 11. P-T diagram showing estimated conditions for the deformation in high-grade schist (light gray areas) and gneiss (dark gray areas). Uncertainties in boundary P-T conditions of the different deformations are shown by question marks. Approximate field of migmatite formation is also shown. P-T grid for pelites is in the KFMASH system, composed from Spear (1993) and references therein. Aluminum silicate triple point after Holdaway (1971). The minimum melting conditions for pelitic rocks and the H2O contents (as XH2O in melt) necessary to saturate the granitic liquid are from Le Breton and Thompson (1988). The garnet-plagioclase-rutile-ilmenite-quartz reaction is from Bohlen and Liotta (1986). The corundum-in and muscovite-out reactions are from Helgeson et al. (1978).
Mineral abbreviations: aluminosilicate (As); andalusite (And); biotite (Bt); chlorite (Chl); cordierite (Crd); corundum (Crn); garnet (Grt); ilmenite (Ilm); kyanite (Ky); muscovite (Ms); orthopyroxene (Opx); phlogopite (Phl); plagioclase (Pl); potassium feldspar (Kfs); quartz (Qtz); rutile (Rt); sillimanite (Sil); and staurolite (St).
Liquid (L) and vapor (V).