Table 3 Intervals of compositional variations in minerals marking different metamorphic stages of garnet-free gneiss

Jd

X_Jd = 0.87–0.99

X_Jd = 0.66–0.83

X_Jd = 0.09–0.2

Na = 0.92–0.99

Na = 0.85–0.96

Na = 0.58–0.87

Fe = 0.02–0.10

Fe = 0.13–0.32

Fe = 0.55–0.81

Ca = 0.01–0.05

Ca = 0.04–0.14

Ca = 0.15–0.35

Mg = 0.00–0.04

Mg = 0.03–0.11

Mg = 0.11–0.24

Cpx

X_Jd = 0.43–0.43

Na = 0.55–0.56

Fe = 0.26–0.27

Ca = 0.41–0.45

Mg = 0.27–0.28

Wm

Si = 3.44–3.53

Si = 3.39–3.44

Al_tot = 1.97–2.07

Al_tot = 2.07–2.13

Ti = 0.00–0.01

Ti = 0.00–0.01

Mg = 0.28–0.32

Mg = 0.28–0.33

Ep

Fe³⁺ =0.61–0.78

Fe³⁺=0.54–0.59

Al_tot = 2.22–2.39

Al_tot = 2.40–2.45

Mn = 0.00–0.01

Mn = 0.01–0.02

Bt

Ti = 0.00–0.01

Al_VI = 0.60–1.02

X_Mg = 0.41–0.56

Pl

X_Ab = 0.95

X_An = 0.02

X_Or = 0.03