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Ushikiri Formation Ministry of International Trade and Industry, 1967

Invalid synonym: Aishiro Formation, Wanibuchi Formation

There is an opnion that Ushikiri Formation is divided to Sandstone/Conglomerate-dominant Aishiro Formation and remaining Josoji Formation.

• Type locality: Ushikiri, Nishitani town, Matsue city, Shimane prefecture
• Coherent formation
• middle Miocene (22 - 14 Ma, FT, Foraminifera)
• Intruded by: Gabbro - Quartz diorite - Dolerite - Porphyrite sills, laccolith, Dikes
• Correlation: Omori Formation

• Sedimentary facies: Marine
• Sedimentary facies: Turbidite, Debris avalanche deposits
• Sedimentary facies (Upper): Submarine pyroclastic flow deposits
• Sedimentary facies (Lower): Submarine volcano
• Depth of water: Continental margin - middle Continental slope (Foraminifera)
• Depth of water: Shallow, upper Bathyal
• Lithofacies (Upper): Dacite pyroclastic rocks
• Lithofacies (Lower): Interbedded sandstone and mudstone, Tuff
• Lithofacies (Minor): Andesite lava, Hyaloclastite, Pillow lava, Volcanic breccia, Rhyolite hyaloclastite, Volcanic breccia, Pillow lava, tuff, Tuffaceous sandstone, Conglomerate
• Sedimentary structures: Groove marks, Slump structures, Graded bedding, Cross stratification, Convolute lamination, Load structures, Wave ripples, Columnar joints
• Paleocurrent: from Southwest to Northeast

• Thickness: ca. 100 - 900 m
• Upper limit: Bottom the sandstone and tuff-deficient horizon
• Upper limit: Transitional (Furue Formation)
• Lower limit: Transitional (Josoji Formation)

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

• Distribution: Cape Nagaohana - Uruppui - Udo - Kawashimo town - Wanibuchi - Inome - Mount Tabushisan, Izumo city, Shimane pref.; Josoji - Ushikiri - Kamihonjo town - Kamisada town - Chikumi - Kasaura - Oashi - Mitsu - Nishitani town, Matsue city, Shimane pref.
• Fossils: Nautilus (Eutrephoceras izumoense), Seaweed
• Fossils (Shellfishes): Acesta goliath, Acesta cf. smithi, Buccinum? sp., Conchocele nipponica, Coptothyris grai, Doliocassis yokoyamai, Dosinia kaneharai, Fulgolaria striata, Nautilus izumoensis, Neptunea koromogawana, Palliolum peckhami, Patinopecten kagamianus, Patinopecten kimurai ugoensis, Phos nakamurai, Propeamussium cf. tateiwai, Schichiheia yokoyamai, Thyasira (Conchocela) nipponica, Venericardia shiobarensis, Yoldia (Yoldia) laudabilis
• Fossils (Foraminifera): Ammodiscus incertus, Ammonia tochigiensis, Ammphicoryna sp., Anomalina glabrata, Bathysiphon eocenica, Bolivinita quadrilatera, Brizalina alata, Brizalina marginata masudai, Brizalina robusta, Buccella frigida, Bulimina inflata, Bulimina striata, Cassidulina kasiwazakiensis, Cassidulina yabei, Chillostomella oolina, Chrysalininella dimorpha, Cibicides cf. floridanus, Cibicides malloryi, Cibicides pseudoungerianus, Cribroelphidium imanishii, Cribrostomoides cf. crassimargo, Cyclammina cancellata, Cyclammina ezoensis, Cyclammina incisa, Cyclammina pusilla, Dentalina sp., Discammina cf. emaciata, Elphidium sp., Epistominella pulchella, Epistominella shimanensis, Furienkaina ishikiensis, Globigerina angustiumbilicata, Globigerina falconensis, Globigerina praebulloides praebulloides, Globigerina praebulloides pseudociperonensis, Globigerina weissi, Globigerina woodi, Globigerinita glutinata, Globobulimina pyrula, Globoquadrina cf. venezuelana, Globoquadrina cf. immaturus, Globorotalia continuosa, Globorotalia quinifalcata, Guttulina yabei, Gyroidina orbidcularis, Gyroidina soldanii, Gyroidinoides shinjiensis, Hastilina bradyi, Hopkinsina shinboi, Islandiella cf. helenae, Lenticulina lucida, Lenticulina nikobarensis, Lituolidae gen. et sp., indet., Martinottiella communis, Martinottiella nodulosa, Melonis pompilioides, Nodosaria sp., Nodosariidae gen. et sp. indet., Nonionella miocenica, Nonionella cf. stella, Oolina costata, Pararotalia tanesawaensis, Pararotalia tochigiensis, Plectina nipponica, Plectofrondicularia miocenica, Pullenia bulloides, Pullenia salisburyi, Reophox pilulifer, Sigmoilopsis schlumbergeri, Sphaeroidina bulloides, Sphaeroidina compacta, Spiroplectammina sp., Spirosigmoilinella compressa, Uvigerina akitaensis, Uvigerina nitidula, Uvigerina proboscidea, Uvigerina segundoensis, Uvigerina subperegrina, Valvulineria masudai
• Tephra: Meoto Tuff

• Kano (2018) Jour. Geol. Soc. Japan, vol.124, no.10, pp.781-803 DOI
• Sato et al. (2011) Jour. Geol. Soc. Japan, vol.117, no.8, pp.439-450 DOI
• Tanaka and Nomura (2009) Jour. Geol. Soc. Japan, vol.115, no.6, pp.261-265 DOI
• Utada (2007) Jour. Geol. Soc. Japan, vol.113, no.8, pp.438-453 DOI
• Kano et al. (1998) Geology of the Taisha District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 58p. (in Japanese with English abstract 3p.)
• Kano et al. (1991) Geology of the Imaichi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 79p. (in Japanese with English abstract 5p.)
• Kano and Nakano (1986) Geology of the Etomo District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 30p. (in Japanese with English abstract 3p.)
• Kano and Yoshida (1985) Geology of the Sakaiminato District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 57p. (in Japanese with English abstract 5p.)