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Omi Limestone (Hayasaka, 1921) Nagamori et al., 2010

Invalid synonym: Myojo Limestone

• Type locality: Omi, Itoigawa city, Niigata prefecture
• Oceanic island in the Panthalassa ocean
• Slabs in the accretionary complex
• Deposition: Visean, Mississippian, Carboniferous - Capitanian, Guadalupian, Permian (Fusulinids)
• Accretion: Permian
• Correlation: Akiyoshi Limestone, Taishaku Limestone

• Sedimentary facies: Marine
• Sedimentary facies: Reef complex on an oceanic island
• Sedimentary facies: Sediment gravity flow deposit on the reef slope, Deposit on the reef core, Beach at the back reef to reef lagoon
• Lithofacies (Upper): Grainstone, Packstone
• Lithofacies (Lower): Grainstone, Rudstone, Boundstone, Chert
• Sedimentary structures (Lower): Graded bedding

• Thickness: ca. 1,000 m
• Upper limit: Unconformity (Ishizaka Formation)
• Lower limit: Thrust fault, partly transitional (Basalt)

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

• Distribution: Omi - Mount Itagamine - Mount Kurohimeyama - Mount Myjosan - Mount Shimizuyama, Itoigawa city, Niigata pref.
• Fossils: Fusulinids, Crinoids, Bryozoans, Brachiopods, Rugosa, Chaetetes sp., Calcareous algae
• Fossils (Ammonoids): Gastrioceras sp., Branneroceras sp., Eoasitites sp., Paralegoceras sp., Eoasiaties sp., Pseudoparalegoceras sp., Agathiceras sp., Bisatoceras sp., Syngastrioceras sp.

• Takeuchi et al. (2017) Geology of the Tomari District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 121p. (in Japanese with English abstract 4p.)
• Takeuchi et al. (2015) Jour. Geol. Soc. Japan, vol.121, no.7, pp.193-216, DOI
• Ehiro et al. (2010) Jour. Geol. Soc. Japan, vol.116, no.4, pp.219-228 DOI
• Takeuchi et al. (2010) Jour. Geol. Soc. Japan, vol.116, Supplement, pp.123-142 DOI