Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy;Vol.XXIII, No.3


On the Palynoflora in the Paleogene in the Ishikari Coal Field, Hokkaido, Japan

Sato, Seiji

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To clarify the composition and change of the palynoflora in the Paleogene in Central Hokkaido, the samples taken from three representative localities are investigated: the northern and southern parts of the Ishikari coal field and the plain and offshore areas near Yufutsu, south~southwest of the coal field. The palynofloras in the Ishikari coal field do not indicate so warm climate as has generally been supposed. This discrepancy may be interpreted as follows: a montane area existed near the coal field (may be east of it) and much pollen (montane elements) from the flora in the area were supplied to the sedimentary basin in the coal field when the Ishikari Group was formed there. The palynoflora in the coal field, therefore, was composed of the mixture of pollens from very warm lowland floras and these from cool temperate montane floras. On the other hand, the palynofloras in the plain and offshore areas near Yufutsu were accumulated in so remote site from the montane area that the pollens transported to the site are very few and they are mainly composed of the elements of very warm lowland floras. In the successions of the palynofloras from the lowest part to the top of the Paleogene, a noteworthy lowering in temperature, "Terminal Eocene Event", is recognized in between the Ishikari and Poronai stages.