北海道北部地域の新第三系珪藻生層序と10Ma前後の低海水準期の検討

概要

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The Ishikari-Teshio Belt is located in the western side along the Axial Zone of Hokkaido. The study area, located in the northern part of the Ishikari-Teshio Belt, is one of the areas where the Neogene formations are typically developed in Hokkaido. This area has two sedimentary basins, Tempoku and Haboro. In the Haboro Basin, nine diatom fossil zones are recognized from the Denticulopsis lauta Zone (14.85-15.70Ma) to the Neodenticula koizumii-Neodenticula kamtschatica Zone (2.50-3.70Ma), and can be fixed diatom biostratigraphy. They harmonize with reported radiometric ages. Comparing the lithofacies of the formations and the eustacy curve of Haq et al.(1987), sand-facies of the Kinkomanai Formation are well assigned to the sea-level fall around 10 Ma and mud-facies of the Embetsu Formation to the sea-level rise after 5.5 Ma. It is infered that the Sandstone Member of the Kinkomanai Formation around 10 Ma corresponds to the Bannosawa Formation and the sandstone members of the Wakkanai, Higashino and Mashike Formations. They are widely traceable from the northern to central part of the Ishikari-Teshio Belt.
地学団体研究会の論文
1993-09-25