Palynostratigraphic Study of the Nemuro Group.

1989年，Takahashi和上田从北海道东部根室群的Hamanaka-Oborogawa组、Akkeshi组和Tokotan组采集了48个样品，Takahashi从Akkeshi湾周围的Akkeshi组7个样品中检测了565个孢粉形，从Ochiishi湾周围的Akkeshi组和Tokotan组9个样品中检测了768个孢粉形，在长保市海滨沿着的3个Akkeshi组样品中，共采集到36个孢子形化石。根据已有的有孔虫、菊石、虫化石等生物地层学资料，Akkeshi组为Maastrichtian时代，Tokotan组为Danian时代。Akkeshi组和Tokotan组都产生了许多Triprojectacites花粉群，Callistopollenites，Wodehouseia等的花粉粒，这些花粉粒是马斯特里赫特时代的良好指示。Akkeshi组和Tokotan组之间的微植物群变化不是很大。1990年，高桥在根室市的Konbumori采集了11个Tokotan组样品，检查了746个palynom ...更多信息 对9个样品的orphs进行了分类鉴定，共鉴别出176种。本文还将这套Tokotan孢粉植物群与Ochiishi的Tokotan组和Maastrichtian期的孢粉植物群进行了比较。关于Kiritappu组，其中包括主要的砾岩层，只有一些泥岩层分布有限，高桥发现105个孢粉形物从4个样品的Kiritappu和267个孢粉形物从4个样品的Yururi岛。他总共研究了137个物种。Kiritappu组产生了Tokotan组和Akkeshi组的52个共同物种。这些常见的物种大多出现了很长一段时间。Kiritappu组孢粉组合最大的本质区别是，Maastrichtian期特有的Auilapollenites、Callistopollenites、Wodehousiea等没有出现，木兰科的花粉粒出现较新。因此，在Tokotan组和Kiritappu组之间划分白垩纪（Maastrichtian）/第三纪（Danian）界线可能是合理的。少

In 1989, Takahashi and Ueda collected 48 samples from the Hamanaka-Oborogawa, Akkeshi, and Tokotan Formations of the Nemuro Group in eastern Hokkaido and Takahashi examined 565 palynomorphs from 7 samples of the Akkeshi Formation around Akkeshi Bay, 768 palynomorphs from 9 samples of the Akkeshi and Tokotan Formations around Ochiishi Bay, and 36 sporomorphs from 3 samples of the Akkeshi Formation along the seaside of Choboshi. According the previous biostratigraphic data on foraminiferida, ammonoids, inoceramids nannofossils etc., the Akkeshi Formation is of Maastrichtian age the Tokotan Formation is of Danian age. Both the Akkeshi and Tokotan Formations yield many pollen grains of Triprojectacites pollen group, Callistopollenites, Wodehouseia etc. Which are a good indicator of Maastrichtian time. Microfloral change between the Akkeshi and Tokotan Formations is not so large. In 1990, Takahashi collected 11 samples of the Tokotan Formation at Konbumori, Nemuro city, examined 746 palynom … More orphs from 9 samples of it, and discriminated 176 species. This Tokotan palynoflora is compared with that of the Tokotan Formation at Ochiishi and of Maastrichtian age, too. Regarding the Kiritappu Formation which consists of predominant conglomerate beds and only some mudstone beds distributed restrictied, Takahashi found 105 palynomorphs from 4 samples at Kiritappu and 267 palynomorphs from 4 samples from Yururi Island. As a whole, he examined 137 species. The Kiritappu Formation yield 52 common species to both the Tokotan and Akkeshi Formations. Most of these common species appear for very long time. The largest essential difference of the palynomorph assemblage of the Kiritappu Formation is that Auilapollenites, Callistopollenites, Wodehousiea etc. Which appear restrictedly only in the Maastrichtian don't occur and pollen grains of the Magnoliaceae appear newly. Accordingly, it may be reasonable that the Cretaceous (Maastrichtian) /Tertiary (Danian) boundary is drawn between the Tokotan and Kiritappu Formations. Less