Magnetite-Ilmenite Equilibria in Archean Enderbites from the Sutam Complex (Aldan Shield)

摘要

The composition of disintegrated titanomagnetites and ilmenites from Archean enderbites of the Sutam Complex of the Aldan shield has been reconstructed. The values of oxygen fugacity and temperature of tita-nomagnetite-ilmenite mineral equilibrium at 7.5 kbar general pressure are calculated. In the process of gran-ulite metamorphism oxygen volatility varied within log f_(o2), = -14.823 + -16.868 at temperatures T = 723℃-910℃, corresponding to a line parallel to the quartz-ferrosillite-magnetite buffer equilibrium, but about 1.5 orders of log f_(o2) above it. The probable values of oxygen volatility for protoliths of Sutam enderbites were not lower than calculated ones.