Nickel and vanadyl porphyrins in 54 petroleum source rocks from the Nadakayama, the Harigaoka and the Uguisugawa formations of Neogene Tertiary age in the Yashima oil field, Akita Prefecture, Japan were determined.
A profound significance of the results seems to be that there are remarkable difference in the distribution of the relative content of prophyrins among the above formations.
Nickel prophyrins were found in all samples examined with the higher contents in the lower and middle parts of the Nadakayama formation and the lower contents in the overlying Harigaoka and Uguisugawa formations.
Vanadyl porphyrins were classified into two types: A-type (normal type) having α non-soret peak at about 570 mμ and B-type (abnormal type) having α non-soret peak at about 587 mμ.
A-type is detected in 39 per cent of all samples, and generally in the lower and middle parts of the Nadakayama formation. On the other hand, B-type is more widely detected in 70 per cent of examined samples. The content of B-type of the Nadakayama formation shows very irregular distribution, while those of the Harigaoka and the Uguisugawa formations have uniform distribution and similar content in each sample. This difference of the stratigraphic distribution in A- and B-type vanadyl prophyrins will probably give a hopeful clue to the elucidation of the diagenetic mechanism of these compounds.
The Nickel prophyrin contents of the thin layers of the soft and black claystone in the Nadakayama formation which has a rhythmical stratification of Flysch type showed remarkable difference to those of hard or siliceous shale layers of the same formation and rather similar to those of the black mudstone composing the Harigaoka formation.
This fact seems to support the interpretation of Taguchi (1961) that the thin layer of black claystone will correspond to the autochthonous sediments at the time of deposition of the Nadakayama formation.

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K-Ar dating on micas from twelve metamorphic rocks and one granitic rock in the Hitachi district, southern Abukuma plateau, were carried out. Measured ages of metamorphic rocks including so-called Tamadare and Nishidohira gneisses have a range from 101×10⁶ years to 120×10⁶ years. These obtained ages by K-Ar method are roughly correlated to the Middle Cretaceous. On the basis of K-Ar age determinations on metamorphic and granitic rocks, some considerations on the relation between them in the Abukuma plateau are briefly noted.

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Recently, the cross-checking of the different age dating method is one of the important study on the geology. In this report, K-Ar dating on granitic rocks was already reported by Kawano's group. The thin section of the same sample is examined by fission track method. The measured ages by K-Ar method and fission track method agree well each other.

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Observations were made on the synthetic gehlenites obtained by heating the glasses of 2CaO•Al₂O₃•SiO₂ (gehlenite)-CaO•2Al₂O₃ and 2CaO•Al₂O₃•SiO₂ (gehlenite)-CaO•3SiO₂ compositions.
It was observed that the specimens heated under 1100°C-6 hours condition were composed only of gehlenite single phase up to 16.6% CaO.2Al₂O₃ content in the glass composition. The lattice constants a₀ and c₀ of the gehlenite crystallized from the glasses of 2CaO•Al₂O₃•SiO₂-CaO•2Al₂O₃ system were greater than those of pure gehlenite. The more than CaO•2Al₂O₃ component in the glass composition, the greater was the a₀ of gehlenite crystallized therefrom. By prolonged time of heating the a₀ of the gehlenite decreased. At higher temperatures it became smaller near to that of pure gehlenite and separated CaO•2Al₂O₃ crystal.
In the heating experiment of the glasses of 2CaO•Al₂O₃•SiO₂ (gehlenite)-CaO•3SiO₂ composition, gehlenite single phase was obtained up to 11.2% CaO•3SiO₂ composition.
Refractive indices and lattice constants a₀, c₀ of the formed gehlenite decreased continuously with increasing amount of CaO•3SiO₂ component up to 11.2% CaO.3SiO₂ composition. Lattice constants of the gehlenite became greater and near to those of pure gehlenite when crystallized at higher temperatures.
As a result, it was confirmed that gehlenite when crystallized at lower temperatures from the glasses of 2CaO•Al₂O₃•SiO₂-CaO•2Al₂O₃ and 2CaO•Al₂O₃•SiO₂-CaO•3SiO₂ compositions could have unstably more aluminous or more siliceous composition than that of pure gehlenite Ca₂Al₂SiO₇.

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Chemical analyses of mesolites confirmed that cationic substitutions took place in wider ranges than those hitherto advocated by Foster (1965) as Ca=2.5-1.6, Na=5.7-1.0 (0=30). This is further verified by the relatively larger cation-exchange capacity of mesolite determined by Harada, Hara and Nakao (1968).

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