Bulletin of the Mizunami Fossil Museum

Bulletin of the Mizunami Fossil Museum No. 4

Miocene Molluscs and Plants from the Shidara basin, Aichi Prefecture

Hiroshi Shibata, Haruyuki Ina, Koichi Asai, Yasuhiro Ishiguro, Katuki Isobe, Kiyomi Ina, Junko Iwata, Shogo Osawa, Masanao Owaki, Hatsuyoshi Kandori, Koji Shibata, Ritsuko Shibata, Kazuo Taguchi, Masatsugu Fuma

Published: 1977/12/25 　 Page: 61–71, pls. 16–18

The sedimentary rocks occupying the lower portion of the Shidara Group in the Shidara basin contain a prolific marine molluscan fauna. Seventy-four species are represented. Most of them are species widely distributed in the First Setouchi Series of the eastern part of the Setouchi geologic province. A paleoecological study of the molluscan fauna indicates a shallow embayed water environment as the site of deposition for the lower portion of the sedimentary rocks and a slightly protected deep water environment for the upper portion.

The tufts intercalated in the sequence of volcanic rocks overlying the sedimentary rocks have yielded plants at two localities. The fossil flora, which is called the “Shibaishitoge flora” contains 40 species, and the majority of these plants are cool-temperate and warm-temperate elements. The geologic age of the flora is considered Middle Miocene on the basis of its composition and stratigraphic position.