Rb-Sr mineral isochron age was obtained for the unmetamorphozed granodiorite from a dike intruded into the Opirarukaomappu gabbroic complex, southern Hidaka metamorphic belt, Hokkaido, Japan. The isochron gives solidification age of 25.5 Ma with an initial Sr isotope ratio of 0.70362. The obtained age is obviously younger than inferred intensive metamorphic age of 56 Ma in the Hidaka metamorphic belt. The young solidification age is in accord with the other evidences. The hornblende geobarometer of the the granodiorite implied that it crystallized in a shallow crust. The granodiorite dike rocks have more evolved nature than the host diorite, but they are not co-magmatic.

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Petrographical, petrochemical and Rb-Sr geochronological data are presented for two Paleogene granitic stocks (the Deokdong and Girimsa Granites) in the eastern part of the Kyeongsang Basin, southeast Korea. Both granites intrude the Eocene Wangsan Formation, and are unconformably overlain by Lower Miocene sedimentary and volcanic rocks. They are I-type and magnetite series granitoids, in common with most other Cretaceous-Paleogene granitic rocks in the Kyeongsang Basin. The Deokdong and Girimsa Granites have whole rock isochron ages of 42.1±5.9 (2σ) and 34.3±3.3 (2σ) Ma, with low initial Sr isotope ratios of 0.70542±0.00030 (2σ) and 0.70570±0.00030 (2σ), respectively. The initial Sr isotope ratios are comparable with those of the majority of the Cretaceous-Paleogene granitic rocks in the Kyeongsang Basin, and also compare well with those of Cretaceous-Paleogene granitic rocks in the San'in Belt and northern Kyushu, southwest Japan. This suggests that the Cretaceous-Paleogene granitic rocks in the Kyeongsang Basin and in the San'in Belt and northern Kyushu of southwest Japan were derived from isotopically similar source materials. The new and previously reported age data suggest that felsic to intermediate magmatism continued intermittently from the Cretaceous into the late Paleogene in the eastern part of the Kyeongsang Basin, although magmatism had practically ceased in the greater part of the basin by the end of Paleocene. Geochronologically, the two granites can be correlated with the Paleogene Namariyama Intrusives in the San'in Belt of southwest Japan. Taking the distribution of the Eocene Oligocene igneous rocks into account, it is suggested that Cretaceous-Paleogene magmatism migrated to a narrow belt along the East Sea (Japan Sea), in both Korea and southwest Japan. The geochronological and Sr isotope data obtained in this study are consistent with the suggestions that the Eocene Oligocene magmatism can be ascribed to upwelling of a mantle plume, which probably initiated the opening of the East Sea (Japan Sea).

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Levyne was found in the cavities of biotite-hornblende-orthopyroxene andesite intruding into Paleogene Kuma formation at the Chuyo quarry, Kodono Kuma-cho, Ehime Prefecture. It is colorless with vitreous lusterand forms thin hexagonal plates up to 4 mm in diameter, being frequently associated with epistilbite. Other cavities contain laumontite, ferrierite, mordenite, heulandite, stilbite, chabazite, apophyllite and calcite. Cell dimensions are a=13.35 (3) and c=22.55 (6) Å. Refractive indices are ω1.497 (2) and ε1.486 (2). EPMA analyses yield anhydrous empirical formulae as follows: Ca_1.81Na_1.63K_0.03Mg_0.13Sr_0.10 (Fe_0.01³⁺Al_5.31Si_12.58) _Σ17.90O₃₆ and Ca_1.73Na_1.96Mg_0.01Sr_0.03 (A1_5.33Si_12.55) _Σ17.88O₃₆ on the basis of O=36. Kodono's material is characterized by highest Si/Al ratio (=2.37) of levynes reported to date.

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