Limestone is accompanied with widely distributed Ryoke metamorphic rocks in islands of the Seto Inland Sea. Ko-Oge Island is situated in this zone and mainly composed of pelitic hornfels and crystalline schist rarely interbedded with dark color and massive Al-Fe rich sediments, so called emery. Emery from Ko-Oge Island is charactarized by high TiO2 contents and by relict of primary texture such as pisolitic one. Emery can be divided, according to the mineral assemblage and texture of rocks: 1. zone of emery, 2. metasomatic zone of emery, 3. metasomatic zone of emery with limestone, and 4. metamorphic zone of another emery. The main constituent minerals of Zone1 are corundum, hercynite, ilmenite, and plagioclase, which occur as granoblastic aggregates. Perovskite, grossular, and vesuvianite occur in Zone 3. It was concluded that emery of Zone 3 is formed by Ca metasomatism in later stage of the prograde and retrogrede stages of metamorphism. Original rock of emery is probably sediment such as laterite, rich in the TiO2, Al2O3, and Fe oxide. The rock is composed of gibbsite, Fe-hydrooxide, anatase, kaolinite, and calcite.
Precision of the degree of graphitization (GD) is evaluated based on repeated experiments on a sample of pelitic schist, and analyses on ten pelitic schists collected from an outcrop. The experimental error is ±2 in two sigma confidential level at GD=31 and GD=26, respectively. The results suggest that if GD value difference is larger than 6, two neighboring samples have the discontinuous metamorphic grade. The systematic sampling and experiments along the direction normal to the strike, revealed the discontinuous boundaries of the metamorphic grade existing at a upper stream of the Sanbagawa-river and at an outcrop of the Arakawa-river, i.e., the boundaries between the shuffled cards Miyashiro (1994). The former boundary is serpentinitic greenschist within the pelitic schists, the latter one, the thrust plane in pelitic schists. A thick layer having continuous GD value also exists in the Sanbagawa metamorphic terrain as revealed by the experiments of the Kamabuse-yama boring core of 280m depths.
Saturation pressures of H2O+NaCl and H2O+KCl solutions are calculated at temperatures from 100° to 600°C and from 100° to 410°C, respectively. Salt concentrations are 1 to 6 molal for the NaCl solutions and from 1 to 4 molal for the KCl solutions. Those calculations are based on the Pitzer and the Tanger-Pitzer equations. The methods of the calculations are reviewed.