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Miyako Group Yabe and Yehara, 1913

• Type locality: Hiraiga, Tanohata city, Shimohei county,, Iwate prefecture
• Coherent formation
• Ezo forearc basin
• Early Cretaceous, Aptian - Albian (Ammonoids)

• Sedimentary facies (Upper - Middle): Marine
• Sedimentary facies (Bottom): Fluvial
• Sedimentary facies (Upper - Middle): Bay-head delta front, Lower shoreface, Shlef
• Sedimentary facies (Bottom): Bay-head delta
• Water temperature: 18 degree C (¹⁸O/¹⁶O)
• Depth of water: Shallow
• Lithofacies: Calcaeous sandstone, Shell limestone, Gravelly sandstone
• Lithofacies (Minor): Sandy siltstone
• Lithofacies (Bottom): Conglomerate

• Thickness: 120 - 200 m
• Upper limit: Unknown
• Lower limit: Unconformity (Harachiyama Formation, Omoto Formation, Miyako Group)

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

• Distribution: Hideshima - Taro - Masaki - Kuwagasaki - Takonohama seashore, Miyako city, Iwate pref.; Moshi, Iwaizumi city, Shimohei county, Iwate pref.; Hiraiga, Tanohata city, Shimohei county,, Iwate pref.
• Fossils: Ammonoids (Hypacanthoplites subcornuerianus, Nolaniceras yaegashii), Nautiloids (Cymatoceras pseudoneokomiensis), Belemnites, Decapods, Echinoids, Crinoids, Foraminifera (Orbitolina sp.), Calcareous algae (Lithothamnium? sp., Pterophyton miyakoense, Stenoporidium chaetetiformis), Wood fragments (Dadoxylon sp.)
• Fossils (Bivalves): Amphidonte (Amphidonte) subhaliotides, Antiquilima ultima, Cardita? sp., Ctenoides subrapa, Cucullaea acuticarinata, Gervillia (Gervillia) forbesiana, Glycimeris (Glycimerita?) haipensis, Leeompteus cf. guerangeri, Limatula ishidoensis, Liostrea cunabula, Lopha (Lopha) nagaoi, Mytilus? sp., Nanonavis yokoyamai, Opis (Opts) nakanoi, Pholadomya subpedalnalis, Praecaprotina yaegashii, Pseudocardia cf. tenuicosta, Pterotrigonia hokkaidoana
• Fossils (Gastropods): Ataphrus yokoyamai, Desmieria japonica, Natica importuna, Potamides? (Exechestoma?) sp.
• Fossils (Corals): Amphiastrea sp., Cyclolites? japonica, Eugyra? magnus, Favia haipensis, Heterocoenia sp., Kobya ragaensis, Kobya ragaensis nagaoi, Leptophyllia sp., Meandrarea sp., Microsolena yabei, Montastrea nagaoi, Placocoenia hideshimaensis, Pleurosmilia hideshimaensis, Pleurosmilia cf. renevieri, Polyphylloseris iwateensis, Thamnasteria hideshimaensis, Thamnasteria hiraigaensis, Thecosmilia hideshimaensis, Thecosmilia (Latiphyllia) sp.

• Urakawa et al. (2017) Jour. Geol. Soc. Japan, vol.123, no.3, pp.121-130 DOI
• Umetsu et al. (2013) Jour. Geol. Soc. Japan, vol.119, Supplement, pp.82-95 DOI
• Terabe and Matsuoka (2009) Jour. Geol. Soc. Japan, vol.115, no.3, pp.130-140 DOI
• Yoshida and Katada (1984) Geology of the Miyako District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 44p. (in Japanese with English abstract 6p.)
• Shimazu et al. (1970) Geology of the Taro District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 54p. (in Japanese with English abstract 6p.)