Palynostratigraphic investigation of the Akkeshi and Tokotan Formations of the Nemuro Group

The authors have made a palynostratigraphic investigation of the Akkeshi and Tokotan Formations of the Nemuro Group which is distributed in the coastal areas between Kushiro and Nemuro. They have collected 48 samples in total from the Oborogawa-Hamanaka, Akkeshi and Tokotan Formations and distinguished 311 palynomorphs which consist of 121 spores, 55 gymnospermous pollen and 135 angiospermous pollen, excepting phytomicroplankton. Recently it was considered that the Nemuro Group may cover Campanian-Danian time. In fact, Yoshida & Kiminami (1980) and Yoshida (1981) pointed out that the Akkeshi Formation belongs undoubtedly to Maastrichtian time by some ammonoids and inoceramid and the Tokotan Formation is in Danian time by planktonic foraminifera and nannofossils. The authors have examined 34 angiospermous pollen, 9 gymnospermous pollen, and 18 spores which were picked up from among 311 palynomorphs as a good age-indicator. Consequently, these from the Akkeshi Formation indicate compatibly Maastrichtian time. In the Tokotan Formation angiospermous pollen grains increase more in number and kind than in the Akkeshi Formation, but Aquilapollenites pollen group decreases in opposition and two new species of Aquilapollenites appear as a newcomer. After all, they could find no evidence supporting Danian time in palynological standpoint