Fe-Ti酸化鉱物の地質温度計と酸素分圧計の数式化について

正則溶液モデルの場域合

抄録

Equilibrium thermodynamic methods are used to develop Fe-Ti oxide geothermometer and oxygen barometer from the experimental data of Buddington and Lindsley (1964). The regular solution approximation for both hematite ilmenite solid solution (alpha phase) and magnetite-ulvospinel solid solution (beta phase) is done in this method. The geothermometer and oxygen barometer are presented graphically and formulated numerically for coexisting alpha and beta phases in the FeO-Fe₂O₃ TiO₂ system. Uncertainty of the geothermometer and the oxygen barometer is ± 11 for temperature (°C) and ± 0.32 for log fo₂ within the experimental conditions of Buddington and Lindsley. The maximum difference of the equilibrium temperature and oxygen fugacity estimated by the graphical method of Buddington and Lindsley and the present thermodynamic method for natural coexisting ilmenite and magnetite is 180°C for temperature and 5 for log fo₂ so far.