Blueschists associated with serpentinites are found in the Mikabu Greenstones of eastern Kii Peninsula. The serpentinites are classified into two types: massive serpentinites and serpentinite conglomerates. Blueschists occur as thin layers (6-250cm wide), and are intercalated with the serpentinite conglomerates. Talc-carbonate rocks are developed along the boundary between blueschists and serpentinite conglomerates. The blueschists, talc-carbonate rocks and surrounding Sanbagawa schists are folded with E-W trending fold axis. Both the blueschists and Sanbag-awa schists have similar mineral lineations plunging gently to the east or to the west.
Major metamorphic minerals of the blueschists are magnesioriebeckite, aegirine-aegirine-augite, muscovite, calcite, quartz and hematite. The blueschists, talc-carbonate rocks and serpentinite conglomerates characteristically contain detrital minerals: brown amphibole, colorless amphibole and chromian spinel.
These petrographic data suggest that (1) the serpentinite conglomerates and protoliths of blueschists and talc-carbonate rocks were sedimentary mixture of siliceous, calcareous and mafic materials, and (2) they were recrystallized during the Sanbagawa metamorphism. The blueschists and serpentinite conglomerates represent siliceous and mafic parts of the original sedimentary sequence, respectively.

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Biotite separates from granodiorites of the Tanigawadake Pliocene plutonic body, North Fossa Magna, central Japan were dated by K-Ar method. The ages range from 3.91±0.27 Ma to 2.9±2.4 Ma.
Petrological and mineralogical features suggest that the youngest granodiorite is an intrusion into the Tanigawadake Pliocene plutonic body.
Relationship between altitude and ages of rocks inferred that uplift rate of the Tanigawadake Pliocene plutonic body was about 1, 400 m/Ma during 3.91-3.40 Ma. This value suggests that the North Fossa Magna region experienced at least 5, 500m of uplift which is in accordance with the previous conclusion expressed by other workers.

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Sr isotope compositions were determined for anorthite megacrysts, olivine phenocrysts and host basalts of Miyakejima volcano, Izu-Ogasawara arc, Japan. The anorthite megacrysts are of An_97-94 in composition. The olivine phenocrysts have almost the same composition (Fo_84-82) as olivine inclusions in the anorthite megacrysts.
The ⁸⁷Sr/⁸⁶Sr ratios of anorthites range within a narrow variation of 0.70340-0.70352, while those of olivine phenocrysts and olivine inclusions show distinctively higher values (0.70357-0.70374) than those of anorthites. Host rock samples excluding megacrysts yield intermediate ⁸⁷Sr/⁸⁶Sr values between anorthite and olivine. This disequilibrium in ⁸⁷Sr/⁸⁶Sr ratios between phenocrysts and host rocks demonstrates that anorthites and olivines did not crystallize directly from the host magmas but were probably xenocrysts carried up by the magmas. The present data further suggest that the olivine phenocrysts and olivine inclusions in anorthite megacrysts have the same origin and that the crystallization of anorthite occurred posterior to olivine crystallization. The difference in ⁸⁷Sr/⁸⁶Sr ratios between olivine inclusions and host anorthite megacrysts provide an evidence for magma mixing between two types of magmas (both of basaltic in composition) with different ⁸⁷Sr/⁸⁶Sr ratios. The basaltic magmas which formed the Miyakejima volcano may also be explained by the mixing of above two end member magmas, at least in some stage (or stages) of magma evolution.

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On-yama is one of the Cenozoic small monogenetic volcanoes which are clustered in and around the Tsuyama Basin, southwest Japan. Both alkali basaltic breccia and lavas of On-yama have abundant ultramafic xenoliths, which are small in size (<5cm across). Lherzolite is predominant among the xenoliths. Small amounts of other xenoliths of both Group I (wehrlite and pyroxenites) and Group II (clinopyroxenite) and megacrysts (clinopyroxene, spinel and phlogopite) are associated with lherzolite. Absence of dunite is characteristic of the On-yama xenolith suite.
The On-yama lherzolite has a rock-by-rock uniformity in mineralogy, having olivine of Fo_89-90 and chromian spinel of Cr # (=Cr/(Cr+Al) atomic ratio)=0.10-0.15. It is always enriched in clinopyroxene; the cpx/(opx+cpx) volume ratio is higher than 0.1. The low refractoriness of the On-yama lherzolite is correlated with the low frequency of associated dunite and other cumulative ultramafic xenoliths. The On-yama lherzolite may be representative of the least refractory part of the upper mantle beneath the Japan arcs.

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