東北地方の二三亞炭層の花粉分析について
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概要
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Pollen-analytical studies were carried out of some lignite beds in the north-eastern provinces of Japan-those in the neighbourhood of Sendai, of Shinjo (Yamagata Pref.) and of Daijima, Oga Peninsula (Akita Pref.). Samples were subjected to microscopic examination after boilong in a 10 per cent caustic potash solution, disintegrating and then adding glycerin. 1. The upper, middle and lower Pliocene lignite beds in the environs of Sendai belong to the Yagiyama-, Kitayama- and Kameoka-formation respectively. The upper lignite bed contains woody pollen which reminds us of the present-day forests, while those characteristic of a warmer climate are found in the lower bed. Woody pollen in the middle bed are intermediate in this respect. Among the plants whose pollen are found in the lignite beds but not living in Japan to-day are Sequoia (or Metasequoia), Liriodendron and Liquidambar. From the pollen-analytical point of view, it seems likely that passing from the lower into the upper the climate deteriorated. 2. Stuides in collaboration with Takahashi were carried out of Pliocene lignites at Funagata (Heiwa mine), Motoaikai (Yamato mine) and Mamurogawa (Hiraoka mine) in the environs of Shinjo, which belong to the Shimizu formation at the middle of the Mogami group. In view of the similar results of pollen analyses, these lignites are considered to be of much the same geological age and are akin to the upper two beds in the evnirons of Sendai. The abundance of the Alnus as well as the occurrence of extinct trees such as Liquidambar, the Taxodium type and possibly Cunninghamia are to be noted. 3. Lastly, Middle Miocene lignites near Daijima were dealt with pollen-analytically. The Daijima formation has long been known to be fossiliferous, but not until quite recently were fossils found in the underlying so-called Sugoroku formation. However, fossil plants have recently been discovered for the first time by Huzioka and Inoue above the lignite bed in the upper part of the Sugoroku formation at a point near Sugorkou Village. And the flora ascertained by the fossil plants there is just the same as that of the Daijima formation already known. Thus, they concluded from geological viewpoints that the upper part of Sugoroku formation is not far in age from the Daijima formation, and ought to be included rather in the Daijima formation itself as the same biofacies. Pollen observed in the lignites of the Daijima formation and the upper part of the Sugoroku formation near Sugoroku Village are almost identical with those of the Pliocene lignites in the environs of Sendai and of Shinjo. From the point of view of pollen analyses essential differences may not be found between the lignite of the Daijima formation and that of the upper part of the Sugoroku formation. These pollen floras of the lignites are more or less approximate to the fossil flora near the middle of the Sugoroku formation revealed also recently by Huzioka and Inoue in the neighbourhood of Monzen Village than to the fossil flora of the Daijima formation or of the upper part of the Sugoroku formation near Sugoroku Village.
- 日本生態学会の論文
- 1954-03-25