著者

高橋 清 山野井 徹

出版者

〔長崎大学教養部〕

雑誌

長崎大学教養部紀要 自然科学篇 (ISSN:02871319)

巻号頁・発行日

vol.32, no.2, pp.p187-220, 1992-01

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The junior author, Yamanoi, collected and analyzed 22 siltstone and claystone samples from the Katsuhira Formation spanning the Cretaceous/Tertiary (K/T) boundary in Kawaruppu area of eastern Hokkaido. The K/T boundary was decided on the basis of planktonic foraminifera by Saito et al. (1986). Recently, the senior author, Takahashi, has examined 66 slides which were prepared by Yamanoi and recognized 64 triprojectate, 6 oculata, and 14 other pollen grains which are palynostratigraphically useful (Tables 1 and 2). However, a remarkable palynofloral change at/near the K/T boundary in Kawaruppu afea is not recognized. Especially, many kinds of the triprojectate-oculata pollen did not disappear at the K/T boundary. On the other hand, the major palynofloral change at the K/T boundary in western North America occurred, including the abrupt disappearance of all species of Aquilapollenites except A. spinulosus, as well as the disappearance of Wodehouseia spinata, Cranwellia striata, Proteacidites spp., and others. They are replaced by such species as Wodehouseia fimbriata, Alnus trina, and Carpinus subtriangula (Lerbekmo et al., 1979). In this region the palynomorph break takes place a few meters above the highest occurrence of dinosaur bones, notably Triceratops. In short, the K/T boundary in this region is defined by the palynofloral change. A climatic condition of biotic change at Kawaruppu in eastern Hokkaido may be different from that in western North America. This problem must be solved in the near future.