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Imaura Formation Yamagiwa, 1957

Invalid synonym: Imaura Group

• Type locality: Horikiri bridge - Mount Aonominesan, Matsuo town, Toba city, Mie prefecture
• Coherent formation
• Fore-arc basin sediments
• Deposition (Limestone): Late Jurassic (Corals, Stromatoporoids)
• Deposition (Mudstone): Middle - Late Jurassic, Early Cretaceous (Radiolarians)
• Correlation (Limestone): Torinosu Group

• Sedimentary facies: Shallow marine
• Sedimentary facies (Limestone): Reef slope of coral reef
• Lithofacies: Mudstone, Sandstone, Interbedded sandstone and mudstone
• Lithofacies (Minor): Limestone
• Sedimentary structures: Wave-formed ripples

• Thickness: 200 m or thicker
• Distribution (East - West): ca. 1 km
• Distribution (South - North): ca. 100 m
• Lower limit: Unconformity (Tsuiji Complex)

• Distribution: Horikiri bridge - Mount Aonominesan - Imaura, Toba city, Mie pref.; Izumigawa river, Minamiise city, Watarai county, Mie pref.; Erihara - Aonomine bridge - Setodani, Isobe town, Shima city, Mie pref.
• Fossils: Ammonoids (Hybonoticeras cf. hybonotum, Orthosphinctes (Ardescia) cf. enayi), Echinoids, Bivalves, Gastropods
• ���� (Radilarians): Actinomma sp., Archaeodictyomitra cellulata, Archaeodictyomitra rigida, Archicapsa sp., Bistarkum irazuense, Cinguloturris carpatica, Dictyomitrella? kamoensis, Droltus sp., Eucyrtidiellum nodosum, Eucyrtidiellum ptyctum, Gongylothorax favosus oviformis, Helvetocapsa? prealpina, Hiscocapsa sp., Hsuum baloghi, Hsuum brevicostatum, Hsuum maxwelli, Kilinora spiralis, Loops doliolum, Loopus primitivus, Napora sp., Obesacapsula magniglobosa, Pantanellium sp., Parahsuum carpathicum, Paronaella bronnimanni, Paronaella kotura, Paronaella mulleri, Paronaella pygmaea, Plicaforacapsa catenarum, Pobursa sp., Praewilliriedellum cephalospinosum, Praewilliriedellum spinosum, Protunuma? ochiensis, Pseudodictyomitra? sp., Pseudoeucyrtis firmus, Pseudoristola nova, Pseudoristola tsunoensis, Sethocapsa aitai, Spongocapsula sp., Spongurus sp., Stichocapsa magnipora, Striatojaponocapsa conexa, Striatojaponocapsa synconexa, Tethysetta sp., Tetracapsa sp., Tricolocapsa? fusiformis, Tricolocapsa plicarum, Tritrabus exotica, Tritrabs zealis, Triversus hungaricus, Triversus japonicus, Triversus schardti, Williriedellum dierschei, Wrangellium sp., Xitus aff. pulcher, Zhamoidellum ovum
• Fossils (Limestone): Hexacorallia, Tabulate corals, Echinoids (Cidaris sp.), Foraminifera, Stromatoporoids

• Uchino et al. (2017) Geology of the Toba District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 141p. (in Japanese with English abstract 5p.)
• Uchino and Suzuki (2017) Jour. Geol. Soc. Japan, vol.123, no.12, pp.1015-1033 DOI
• Uchino and Suzuki (2016) Jour. Geol. Soc. Japan, vol.122, no.5, pp.207-222, DOI