Ehiro et al., 2020 Geological age of the Ayukawa Formation

[mhorn]

Ehiro, M., Takaizumi, Y., Hanamatsu, S. I. (2020). Geological age of the Ayukawa Formation (Oshika Group) in the South Kitakami Belt, Northeast Japan based on the ammonoids // The Journal of the Geological Society of Japan, Vol. 126. no.10, P.563-574.

https://www.jstage.jst.go.jp/article/ge ... f/-char/en

Изображены и описаны валанжинские аммониты из пачки Futawatashi Shale Member южной части пояса Китаками (СВ Япония): Olcostephanus atherstoni, O. cf. stephanophorus, Busnardoites aff. campylotoxus и Neocomites? sp.