Maestrichtian Micro flora of the Miyadani-gawa Formation in the Hida District, Central Japan
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概要
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114 species of miospores and a freshwater alga from the Miyadani-gawa Formation in the Hida district of central Japan are systematically described and illustrated. Among the miospores 2 species belong to mosses, 24 to ferns, 13 to gymnosperms and 75 to angiosperms. Most characteristic of the assemblage and important for its age determination are the triprojectate pollen group and the genera Wodehousea and Callistopollenites. The pollen group Triprojectacites including 10 genera and 43 species is studied in detail. Many previously described species of this group have been re-examined and recombined. Nine species of the triprojectate pollen group, two species of Wodehousea and two of Callistopollenites, which occur characteristically in the Miyadani-gawa Formation, have previously been reported from the Maestrichtian of Siberia, North America, Hokkaido (Japan) and other regions and thus undoubtedly indicate a Maestrichtian age for the Miyadani- gawa Formation as well, contrary to the traditional assumption of Palaeogene or Neogene age. The freshwater aiga Pediastrum occurs at two horizons of the Miyadani-gawa Formation. This occurrence, in conjunction with the nature of the sediments,leads the authors to envisage the existence of a former freshwater lake, "Palaeolake Kokufu", extending about 10.5km from east to west and about 7 km from north to south. Key words ; Miyadani-gawa Formation---Maestrichtian---triprojectate pollen group.
- 〔長崎大学教養部〕の論文
〔長崎大学教養部〕 | 論文
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