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Chinen Formation (Flint et al., 1959) Noda, 1977

Invalid synonym: Chinen Sandstone Member of Naha Formation, Chinen Sand of Ryukyu Group

There are opinions that this formation is a part of Naha Formation, Ryukyu Group, or of Shimajiri Group.

• Type locality: Azama - Kudeken, Chinen, Nanjo city, Okinawa prefecture
• Coherent formation
• Pleistocene, Gelasian - Calabrian (1.7 - 1.4 Ma, Calcaeous nannofossils)

• Sedimentary facies: Marine
• Depth of water: Upper continental slope (100 - 300 m)
• Lithofacies (Upper): Sandy limestone
• Lithofacies (Lower): Calcareous siltstone, Sandstone

• Thickness: 15 - 60 m
• Thickness (Upper): ca. 30 m
• Thickness (Lower): 10 - 30 m
• Upper limit: Partly conformity, Partly unconformity (Naha Formation)
• Lower limit: Partly conformity, Partly unconformity (Shimajiri Group)

• Distribution: Azama - Kudeken, Chinen, Nanjo city, Okinawa pref.; Tsukazato - Komesu, Itoman city, Okinawa pref.; Gizabanta - Gushikami seashore - Asato - Aragusuku, Yaese city, Shimajiri county, Okinawa pref., Miyagi island, Okinawa pref.; Henza island, Okinawa pref.; Hamahiga island, Okinawa pref.; Ikei island, Okinawa pref.
• Fossils: Bivalves, Brachiopods, Echinoids, Foraminifera, Bryozoans
• Fossils (Calcaeous nannofossils): Calcidiscus leptoporus, Calcidiscus macintyrei, Gephyrocapsa caribbeanica, Gephyrocapsa oceanica, Helicosphaera carteri, Helicosphaera sellii, Pseudoemiliania lacunosa, Reticulofenestra sp., Rhabdosphaera clavigera, Syracosphaera pulchra, Umbilicosphaera sibogae
• Fossils (Foraminifera): Amphistegina bicirculata, Amphistegina lobifera, Amphistegina papillosa, Amphistegina radiata, Calcarina mayori, Calcarina hispida, Cibicides sp., Cibicidoides sp., Eponides sp., Heterostegina depressa, Neoeponides sp., Operculina spp., Operculinella sp., Reophax sp., Rosalina sp., Pseudorotalia papillosa, Textularia spp.

• Sagae et al. (2012) Jour. Geol. Soc. Japan, vol.118, no.2, pp.117-136 DOI
• Fujita et al. (2011) Jour. Geol. Soc. Japan, vol.117, no.11, pp.625-631 DOI
• Chiyonobu et al., (2009) Jour. Geol. Soc. Japan, vol.115, no.10, pp.528-539 DOI