From the rare earth element (REE) patterns and Ba, Rb, and Sr relationships of granitoids of South Korea and Southwest Japan, we have found two types of granitoid magmas. These are: 1) Granitoid magmas mainly differentiated by the process of fractional crystallization. These are typified by the Cretaceous granitoids of South Korea and the granitoids younger than Cretaceous in Southwest Japan; and 2) Granitoid magmas formed by the process of partial melting of the lower continental crust in the presence of hornblende, or derived by the process of fractional crystallization of quartz dioritic magmas with removal of hornblende. These are typified by the Jurassic granitoids of South Korea.

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The compositional systematics of biotites and hornblendes from the batholiths of California have been examined for the purpose of assessing the effects of temperature and pressure of crystallization on the distribution of Fe and Mg among coexisting mafic silicates in granitic rocks. Thermodynamic calculations indicate that at magmatic conditions, Fe-Mg exchange between biotite and amphibole is probably not a strong function of crystallization temperature. However, theoretical predictions and natural mafic phase compositions show that the Fe-Mg distribution is dependent upon amphibole composition. Specifically, decreases in amphibole total Al and A-site occupancy lead to increases in the Mg/(Mg+Fe^T) of amphibole relative to the Mg/(Mg+Fe^T) of coexisting biotite. In magmas containing the appropriate igneous buffering assemblage, amphibole Al content is positively correlated with crystallization pressure (cf. Hammarstrom and Zen, 1986). In these magmas, the distribution of Fe and Mg between coexisting amphibole and biotite is primarily a function of consolidation pressure, owing to the dependence of Mg/(Mg+Fe^T) on Al content in amphibole. Variations in natural amphibole chemistry as a function of crystallization pressure indicate that the dominant pressure-sensitive coupled substitution in amphibole in the batholiths of California is probably of the form: (A-site)+(Mg+Fe²⁺)+2Si⇔(Na+K)(A-site)+2Al^IV+(Al+Fe³⁺)^VI

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The composition of published fluid inclusion analyses from a porphyry-type deposit are compared with the composition of a calculated magmatic aqueous phase. The calculations are performed by modeling the partitioning of chlorine between an arc magma and an aqueous phase using a Nernstian law, and modeling the partitioning of the elements sodium, potassium, hydrogen, calcium, magnesium, copper, manganese and barium into the chloride-bearing fluid according to experimentally determined exchange constants. The instantaneous concentration of the above elements in successive aliquots of magmatic aqueous phase evolved during second boiling can be calculated as a function of the vapor evolution progress variable. Further, an average concentration of an element in the magmatic aqueous phase (averaged over the course of vapor evolution progress) can also be calculated. The composition of the fluid inclusions can be reproduced using both methods. Magmatic fluid compositions with 2000-3000 ppm copper, 10 wt% chlorine and K/Na ratios=0.5 result from the calculations. Whereas potassium concentrations are slightly depressed, and calcium and magnesium concentrations are elevated in the analyzed fluid inclusions relative to the calculated fluids, the sodium, chlorine, copper, manganese and barium concentrations in fluids extracted from fluid inclusions can be reproduced with these calculations. This study suggests that fluid inclusions of the potassic zone of some porphyry-type deposits represent cooled magmatic fluids which have undergone some exchange with wall rocks but which contains magmatic concentrations of copper, manganese and barium at temperatures below 450°C.

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Chemical compositions of magmatic fluids released from a water-saturated, crystallizing granitic melt are calculated quantitatively. The calculations were performed using the model originally proposed by Holland (1972) incorporating currently available experimental partition coefficient data. The results indicate that the partitioning of metal cations into the fluid phase is strongly dependent on pressure, their fluid-melt partitioning coefficients and chlorine content in the initial granitic melt. Concentration of chlorine and most cations in the fluid phase will generally increase at pressures below 1 kbar, whereas decrease above it, with the progress of crystallization. While crystallization of a granitic magma over a wide range of pressures will yield a fluid phase with high concentration of sodium and potassium compared to calcium, enrichment of the fluid in lead and zinc will likely occur if the fluid release occurs at pressures less than 1 kbar. The calculation suggests that the initial granitic magma should contain chlorine at least in a range of 200-1000 ppm to transport base metals into the aqueous phase effectively. The calculations reported in this study strongly support the validity of the classical hypothesis that chlorine-rich magmatic fluids evolved at shallow depths (below 2 kbar) have the potential of forming hydrothermal base metal deposits.

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The southernmost Hidaka metamorphic belt consists mainly of cordierite tonalite intrusions and pelitic metamorphic rocks ranging from the greenschist to the granulite facies. Anatectic migmatites are common in the higher amphibolite and granulite facies zones. Compositional changes in major, rare earth elements and some other trace metals are so small that they are undetectable among the pelitic metamorphic rocks of zones A + B + C and D, but they are large enough to be detected in the higher amphibolite (zone D) to the granulite facies rocks (zone E). The enrichment of Fe, Mg, Na, Eu, and Sc, and the depletion of K, P, La, Ce, Nd, Cs and Rb are statistically significant in pelitic granulites, while heavy REEs are very variable. The chemical variation of pelitic granulite was derived from the accumulation of plagioclase + garnet. This suggests that more than 50-60% of the total volume of pelitic granulite was melted to produce a large amount of tonalitic magma, leaving pelitic granulite as a restite. Migmatites of the higher amphibolite facies are anatexites, and their K, P, Cs, Rb and light REE content is the same as that of lower grade metamorphic rocks. Migmatites of the higher amphibolite facies melted incipiently to segregate only a small amount of melt, and could not produce a large magmatic mass such as the cordierite tonalites. Cordierite tonalites are S-type granites, and their major elements, Cs, Rb and light REE concentrations are similar to those of lower grade metamorphic rocks. The chemical variation of cordierite tonalites is explained by the extraction of plagioclase + garnet from a tonalitic magma and the variation of original sedimentary rocks. The small chemical difference between the cordierite tonalites and the lower grade metamorphic rocks suggests that the former was derived from a massive melting of metapelites or that much of the restite is retained. The material migration among higher amphibolite facies rocks, pelitic granulites, migmatites and cordierite tonalites took place through mineral/melt interaction in the lower crust.

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Ion exchange experiments in the system CaWO₄-FeWO₄-MnWO₄-(Ca, Fe²⁺, Mn²⁺)Cl₂-H₂O, corresponding to scheelite-ferberite-huebnerite series mineral as solid phase, were carried out at 400 and 600°C under 1000 kg/cm². Ferberite and huebnerite form a continuous solid solution (wolframite ss), which may exhibit thermodynamically ideal behavior. Also, ferrous ion tends to concentrate preferably into wolframite ss than into aqueous chloride solution. This tendency becomes more pronounced with decreasing temperature. Scheelite and wolframite ss do not dissolve into each other essentially, but form a wide miscibility gap. The Ca/(Ca+Fe²⁺+Mn²⁺) mole ratios of aqueous chloride solution coexisting with both minerals are about 0.65 at 400°C and 0.3 at 600°C. Temperature has a significant effect on the mole ratio, although a slight variation due to the compositional change of wolframite ss is recognized. The present experimental results cast a doubt on “wolframite geothermometer”.

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