C-O-H Fluid Calculations and Granulite Genesis

TL;DR: In this article, it was shown that most of these fO2 values are consistent with either H2O rich or vapor absent conditions assuming the fraction of non C-O-H components is relatively small.

Abstract: Pervasive flooding of CO2 into the deep crust has been proposed as the cause of granulite facies metamorphism One effect of CO2 infiltration would be the dilution of H2O and the stabilization of orthopyroxene-bearing assemblages Calculations in the C-O-H system indicate that infiltration of CO2 into rocks whose oxygen fugacities are buffered to within the stability of graphite will cause graphite to precipitate Oxygen fugacities determined from coexisting magnetite and ilmenite from three granulite facies terranes are sufficiently low so that it can be shown that most of these samples have not been flooded by sufficient CO2 to form granulites as graphite is not reported Instead, most of these fO2 values are consistent with either H2O rich or vapor absent conditions assuming the fraction of non C-O-H components is relatively small If these values of fO2 are common in rocks which were metamorphosed under conditions of low fH2O then vapor absent metamorphism may be common in granulites