Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy;Vol.XIX, Nos.1-2

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Late Cretaceous Floras from the Kuji District, Norheastern Honshu, Japan

Tanai, Toshimasa

Permalink : http://hdl.handle.net/2115/36676

Abstract

The Upper Cretaceous (Senonian) Kuji Group in northeastern Honshu is divided into three formations, the Tamagawa, the Kunitan and the Sawayama in ascending order. Well-preserved plants are incluaed in the Tamagawa and Sawayama Formations. Fifty-one species of plants from 12 localities are identified; they are made up of 17 pteridophytes, 2 cycadophytes, 10 conifers and 22 angiosperms, all of which are taxonomically described. These two floras from the Kuji Group have many common species, but they are somewhat different in floristic composition. In the Sawayama flora angiosperms predominate in species and specimens, and are followed by various ferns and conifers. On the one hand, the Tamagawa flora is most predominant in ferns, and is less in angiosperms. These two floras are closely similar in composition and components to the "Gyliakian flora" of North Saghalien. Considering the floristic composition together with marine fossils of the Kunitan Formation, the Tamagawa flora is assignable to Santonian, and the Sawayama flora is to Early Campanian age.

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