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Oigawa Group (Makiyama, 1939) Sugiyama, 1995

Invalid synonym: Oigawa Sheet, Utogi Unit, Jumaisan Formation

• Accretionary complex
• Deposition (Limestone): middle Eocene - Oligocene (Foraminifera, Calcareous nannofossils, Radiolarians)
• Deposition (Chert): Oligocene (Radiolarians)
• Deposition (Shale): middle Miocene (Radiolarians)
• Deposition (Mudstone): early - middle Miocene (Radiolarians, Foraminifera)
• Accretion: middle Miocene
• Intruded by: Dolerite, Alkaline dolerite

• Sedimentary facies: Marine
• Sedimentary facies: Trench-fill deposit at the trench and the oceanic side slope of accretionary complex
• Lithofacies: Interbedded sandstone and shale, Shale, Sandstone
• Lithofacies (Upper, Minor): Conglomerate, Gravel-bearing mudstone, Sandstone, Felsic tuff, Tuffaceous siliceous shale
• Exotic blocks (Crusts): Limestone, Reef limestone, Chert, Basalt

• Thickness: 2,500 m
• Distribution (South-North): ca. 70 km
• Distribution (Width): 1 - 2 km
• Upper limit: Conformity (Takakusayama Volcanic Rocks), Unconformity (Sagara Group)

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

• Distribution: Mount Jumaisan, Yamanashi pref. - Shizuoka pref.; Mekami, Makinohara city, Shizuoka pref.; Oshiro, Minobu city, Minamikoma county, Yamanashi pref.; Fujieda city - Shimada city, Shizuoka pref.
• Fossils (Foraminifera): Globigerina ampliapertura
• Fossils (Radiolarians): Actinomma? sp., Actinommidae, Amphisphaera minor, Amphymenium cf. splendiamatum, Artophormis cf. gracilis, Carpocanistrum sp., Carpocanopsis? sp., Collosphaera? sp., Cyclampterium? sp., Didymocyrtis? sp., Dorcadospyris? sp., Eucyrtidium diaphanes, Larcopyle? spp., Liriospyris, Lithelius? sp., Lychnocanoma sp., Periphaena? sp., Podocyrtis? sp., Prunopyle titan, Spireuma? sp., Spongodiscus cf. osculosus, Spongurus spp., Spumellaria, Stichocorys cf. delmontensis, Stylatractus? spp., Stylochlamydium? sp., Dtylodictya sp., Stylosphaera? spp., Theocampe? sp.

• Ozaki and Sugiyama (2018) Geology of the Minobu District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 169p. (in Japanese with English abstract 7p.)
• Sugiyama and Matsuda (2014) Geology of the Nanbu District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 134p. (in Japanese with English abstract 5p.)
• Sugiyama and Shimokawa (1990) Geology of the Shimizu District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 103p. (in Japanese with English abstract 8p.)
• Sugiyama et al. (1982) Geology of the Shizuoka District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 82p. (in Japanese with English abstract 9p.)