能登半島珠洲および氷見-灘浦地域の新第三系泥質岩の有機物相

抄録

The Neogene formations in the Noto Peninsula are widely distributed as an extention of the “Green tuff” basin formed in the inner zone of Northeast Japan. The Suzu and the Himi-Nadaura areas, among them, are well known as the standard Neogene sequences of the Noto-Hokuriku district, Central Japan.
In order to obtain some information on geochemical evaluation for petroleum source rock, 119 argillaceous rock samples collected from each Formations of both areas mentioned above were examined through the stratigraphic variation of organic constituents and maturation obtained by extractable organic matter, visual kerogen and Rock-Eval analysis.
The average values of organic carbon contents of the Nazimi and the Iizuka Formations (Middle Miocene) in the Suzu area, and the Sugata Formation (Middle Miocene) in the Himi-Nadaura area are high more than 2.0 per cent. They are higher than ones of the other Neogene oil field areas along the Japan Sea side. The results of Rock-Eval analysis, however, show that argillaceous source rocks from these Formations are immature in terms of organic maturation. Althogh the source rocks are immature, on the basis of those results and other geochemical and geological information, some considerations on the expectancy for the occurrence of immature hydrocarbon deposits in this distrct have been also presented.