Phase equilibrium studies of the chilled margins of some layered intrusions

The chilled margins of the Michikamau, Muskox, Skaergaard, and Bushveld intrusions were experimentally remelted over a range of f_O2. The observed primary phases, at certain values of f_O2 (generally 10^–12 to 10^–8 atm) correspond with the reported mineralogy of the earliest cumulates. Previous investigations appear to have been conducted at higher values of f_O2 (>10^–6 atm) at which the experimental mineralogy did not relate to the cumulates.October 1973 to October 1974 at Division of Tribophysics, C.S.I.R.O., P.O. Box 4331, Melbourne, Victoria 3001, Australia.