Fig. 4: Continental lower crustal FeOT and SiO2 correlation.

FeOT versus SiO2 in the continental granulite-facies (lower-crustal) rocks, where FeOT represents all Fe taken as FeO, derived from the database of rock compositions from Archean and post-Archean terrains39. The green line shows the linear best fit of the inverse correlation between FeOT and SiO2.