| mhorn | Дата: Saturday, 14.02.2015, 21:45 | Сообщение # 1 |
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| Sato T., Yamada T. (2014) A new Oxfordian (Late Jurassic) Ammonite Assemblage from the Arimine Formation (Tetori Group) in the Arimine Area, southeastern Toyama Prefecture, northern Central Japan // Bulletin of the National Museum of Nature and Science. Series C, Geology & paleontology. Vol. 40. P. 21-55.
Pdf: http://www.kahaku.go.jp/researc....-55.pdf
A rich new Jurassic ammonite assemblage was discovered from the Arimine area in the
southeastern part of Toyama Prefecture. The assemblage is composed of Phylloceras (Phylloceras), Ptychophylloceras, Holcophylloceras, Ochetoceras, Taramelliceras, Perisphinctes (Kranaosphinctes), Perisphinctes (Dichotomosphinctes), and Subdiscosphinctes and is middle Oxfordian in age (Late Jurassic). This assemblage is correlated to the Perisphinctes matsushimai Assemblage Zone established in the Yambarazaka Formation distributed in the upper Kuzuryu area of the Hida Mountains. This zone has the widest geographical distribution of all the ammonite assemblage zones of the Tetori Group. It is known not only in the Hida Mountains but also in other regions of Japan, such as southern Kitakami, Yamizo and Kuga (Yamaguchi) regions. Subdiscosphinctes is represented by a new species, established on a well preserved huge adult shell and other immature specimens. Preservation of big ammonites like Subdiscosphinctes and Perisphinctes s.s. in the Arimine area suggests a particular depositional environment favorable for rapid burial of fragile ammonite shells, which is confined to some limited spots in this area in P. matsusimai Zone time
Middle Jurassic - Lower Cretaceous ammonites & aptychi
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