Namigata Formation

It had been included in First Setouchi Supergroup but was excluded.

Type locality: Namigata, Ibara city, Okayama prefecture
Coherent formation
late Eocene - early Oligocene
Correlation: Kibi Group

Sedimentary facies: Marine
Lithofacies: Sandstone
Lithofacies (Basal): Conglomerate

Thickness: 100 m or thinner
Thickness (Basal): 10 m or thicker

Namigata Formation
[ Upper ]
--------------
Onishi Conglomerate Member
~~~~~~~~~~~~~~
Main part
--------------
Senjuin Shell-Sandstone Member
--------------
Main part
~~~~~~~~~~~~~~
[ Lower ]

------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown

Distribution: Ibara city - Yagake city, Okayama pref.
Fossils: Coptothyris sp., Terebratalia sp., Dentaliidae, gen. et sp. indet
Fossils (Bivalves): Acila (Truncacila) nagaoi, Saccella sp., Glycymeris? sp., Isognomon (Hippochaeta) hataii, Acesta (Plicacesta) takeyamai, Modiolus sp., Septifer sp., Chlamys (Nomurachlamys?) namigataensis, Crassostrea sp., Cyclocardia sp., Felaniella (Felaniella) namigataensis, Cultellus sp., Glauconome sp., iocyma sp., Mactromeris sp.
Fossils (Gastropods): Cellana? sp., Lottia? sp., Margarites? sp., Sinum sp. aff. S. zonale, Turritella (Kotakaella) sp. aff. T. (K.) infralirata, Hipponix? sp., Epitoniidae, gen. et sp. indet, Molopophorus watanabei, Mohnia? sp., Exilia sp., Ficus sp., Turbonilla? sp.

Sato et al. (2022) Geology of the Wake District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 106p. (in Japanese with English abstract 4p.)
Matsubara (2013) Jour. Geol. Soc. Japan, vol.119, no.4, pp.249-266 DOI
Suzuki et al. (2009) Jour. Geol. Soc. Japan, vol.115, Supplement, pp.139-151 DOI