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Hikawa Unit Fujimoto, 1932

Invalid synonym: Hikawa Formation, Kurasawa Formation

• Type locality: Okutama river, Hikawa - Hinokimura, Okutama city, Nishitama county, Tokyo
• Accretionary complex
• Deposition (Chert): Triassic (Conodonts)
• Deposition (Siliceous mudstone): Middle - Late Jurassic (Radiolarians)
• Accretion: Middle - Late Jurassic
• Correlation (Limestone): Torinosu Group

• Sedimentary facies: Marine
• Lithofacies: Coherent facies
• Lithofacies: Sandstone, Interbedded sandstone and mudstone
• Lithofacies (Minor): Gravel-bearing mudstone, Conglomerate, Limestone

• Thickness: ca. 3,500 m
• Upper limit: Thrust fault
• Lower limit: Thrust fault

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

• Distribution: Okutama river, Hikawa - Hinokimura, Okutama city, Nishitama county, Tokyo; Akaizawa - Shirokura - Senzoku - Kurasawa, Okutama city, Nishitama county, Tokyo; Juriki, Akiruno city, Tokyo; Ohinata, Otaki city, Chichibu county, Saitama pref.
• Fossils (Radiolarians): Arcaheospongoprunum sp., Archaeodictyomitra sp., Guexella nuclata, Hsuum sp., Mirifusus sp., Paronacila sp., Parvicingula sp., Protunuma? ochiensis, Sethacapsa intercalus, Stichocapsa asiatica, Stichamitra sp., Tricolocapsa canexa, Tripocyclia sp., Tritrabe sp.
• Fossils (Conodonts): Diplododella acroforma, Neohindeodella aequiramosa, Neohindeodella cf. benderi

• Hara et al. (2010) Geology of the Mitsumine District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 110p. (in Japanese with English abstract 4p.)
• Yamakita and Otoh (2000) Structural Geology, vol.44, pp.5-32
• Sakai (1987) Geology of the Itsukaichi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 75p. (in Japanese with English abstract 5p.)