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Kawai Formation Imamura et al., 1958

Invalid synonym: Oro Formation, Anami Formation, Nabeyama Formation, Lower Tamatsukuri Formation, Yonago Andesite, Kabutoyama Member, Teradani Member, Karakuri Member

• Type locality: Kawai, Oda city, Saitama prefecture
• Coherent formation
• middle Miocene (20 - 12.4 Ma, K-Ar)
• Correlation: Josoji Formation

• Sedimentary facies: Shallow marine
• Sedimentary facies (Minor): Lacustrine
• Sedimentary facies: Coastal - Offshore near the river mouth
• Lithofacies: Tholeiite
• Lithofacies: Conglomerate, Sandstone, Andesite - Dacite - Rhyolite lava, Andesite - Dacite hyaloclastite, Submarine pyroclastic flow deposit, Volcanic breccia (Pillow breccia)
• Lithofacies (Bottom, Minor): Conglomerate
• Sedimentary structures (Minor): Graded bedding, Reversed graded bedding, Parallel stratification, Low-angle cross-stratification
• Sedimentary structures (Lava): Platy joints

• Thickness: 0 - 500 m
• Upper limit: Interfinggered (Kuri Formation), Unconformity (Omori Formation)
• Lower limit: bottom of the felsic tuff bed
• Lower limit: Unconformity (Sada Formation, Hata Formation, Daito Granodiorite, Hiyodori Granite, Satsume Volcanic Rocks, Kamishima Volcanic Rocks, Shiota Body, Hosekidani Body, Shimokuno Granite)

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

• Distribution: Gotsu city, Shimane, Shimane pref.; Kawai - Ushibara - Nima, Oda city, Shimane pref.; Shinji town - Tamatsukuri - Sudani, Matsue city, Shimane pref.; Munakata, Yonago city, Shimane pref.; Takakubo - Suga - Sannoji - Kitamura - Bessho, Unnan city, Shimane pref.; Kisa town - Kadou town, Yasugi city, Shimane pref.; Miyauchi - Unate town - Mimiku town, Izumo city, Shimane pref.
• Fossils: Shellfishes (Freshwater), Fishes, Diatoms (Fluvial)
• Fossils (Shellfishes): Acila sp., Anadara daitokudoensis, Cardium sp., Dosinia sp., Gastropods, Macoma sp., Patinopecten (Kotorapecten) yamasakiensis ninohesis, Pecten sp., Venericardia sp., Vicarya cf. japonica, Vicaryella sp.
• Fossils (Daijima-type flora)
• Fossils (Foraminifera): Ammodiscus incertus, Bathysiphon sp., Cribrostomoides cf. crassimargo, Cyclammina cancellata, Cyclammina pusilla, Discammina compressa Gaudryina ishikiensis, Gaudryina yabei, Grobigerina adamantea, Globobulimina sp., Hippocrepinella sp., Martinottiella communis, Orbulina universa, Plectina nipponica, Recurvoides sp., Reophar spp., Spirosigmoilinella compressa

• Kano et al. (2025) Geology of the Yonago District (2nd Ed.), Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 84p. (in Japanese with English abstract 4p.)
• Kano (2018) Jour. Geol. Soc. Japan, vol.124, no.10, pp.781-803 DOI
• Sawada et al. (2013) Jour. Geol. Soc. Japan, vol.119, no.4, pp.267-284 DOI
• Hayashi et al. (2013) Jour. Geol. Soc. Japan, vol.119, no.4, pp.300-311 DOI
• Sato et al. (2011) Jour. Geol. Soc. Japan, vol.117, no.8, pp.439-450 DOI
• Utada (2007) Jour. Geol. Soc. Japan, vol.113, no.8, pp.438-453 DOI
• Matsuura et al. (2005) Geology of the Kisuki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 72p. (in Japanese with English abstract 5p.)
• Kano et al. (1998) Geology of the Iwami-Oda and Oura District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 118p. (in Japanese with English abstract 5p.)
• Kano et al. (1994) Geology of the Matsue District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 126p. (in Japanese with English abstract 5p.)
• 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.)