| Toyora Group | |
|---|---|
| Stratigraphic range: Early-Late Jurassic ~ | |
| Type | Geological group |
| Sub-units | Higashinagano, Nishinakayama, Utano & Ohchi Formations |
| Underlies | Renge Metamorphic Rocks & Toyohigashi Group |
| Overlies | Toyonishi & Kanmon Groups |
| Thickness | 1,000–2,000 m (3,300–6,600 ft) |
| Lithology | |
| Primary | Mudstone, sandstone |
| Other | Siltstone, conglomerate, acidic tuff |
| Location | |
| Region | Yamaguchi |
| Country |  Japan |
| Type section | |
| Named for | Toyora Gun (Counties) |
| Named by | Yabe |
| Year defined | 1920 |
The Toyora Group is one of the Mesozoic strata in Japan, and was originally named Toyoura Series (or Formation) by Hisakatsu Yabe in 1920.[1] The present name was defined by Tatsuro Matsumoto in 1949.[2]
It is the Lower-Upper Jurassic sediments in the East Asian continental margin that distributes in the eastern part of the Shimonoseki, Yamaguchi Prefecture, southwest Japan. The distribution of the Toyora Group extends north and south, and has been separated between north and south districts by the Tabe Basin and the Kikugawa Fault that is an active left-lateral strike-slip fault.[3][4][5]
- ^ Yabe H., 1920, On the so-called Mesozoic formations in the Kiku Peninsula, Buzen. Jour. Geogr., 32, pp.513-520. (in Japanese) OCLC 1554202
- ^ Matsumoto, T., 1949, The Late Mesozoic geological history in the Nagato Province, southwest Japan, Japan. Jour. Geol. Geogr., 21, pp. 235-243. OCLC 610397819
- ^ Arkell, 1956, Japan and Korea. Jurassic Geology of the World. Oliver&Boyd, London and Edinburgh, pp. 418-430. OCLC 930367265
- ^ Sato, T., 1967, Jurassic-Geological history of Jurassic Period in Japan. Historical geology, 2nd volume. Asakura Publ., Tokyo, pp. 386-407. (in Japanese) OCLC 833343664
- ^ Kiminami, K., 2009, Jurassic System-Toyora Group. In Geological Society of Japan ed., Regional Geology of Japan 6-Chugoku district. Asakura Publ., Tokyo, pp. 95-97. (in Japanese) ISBN 978-4-254-16786-3