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Omori Formation

Invalid synonym: Kimachi Formation

• Type locality: Omori, Kimachi, Matsue city, Shimane prefecture
• Coherent formation
• middle Miocene (16.2 - 13.7 Ma, K-Ar)
• Correlation: Ushikiri Formation

• Sedimentary facies (Upper): Shallow marine
• Sedimentary facies (Lower): Terrestrial, Shallow marine
• Sedimentary facies (Lower, Minor): Surge deposits
• Depth of water: Shallow
• Lithofacies (Upper): Conglomerate, Sandstone, Turbidite
• Lithofacies (Lower): Andesite - Dacite - Basalt lava, Volcanic breccia, Lapilli tuff
• Lithofacies (Lower, Minor): Rhyolite pumice tuff, Andesite lapilli tuff, Accretionary lapilli-bearing tuff, Silicified woods
• Lithofacies (Bottom): Conglomerate
• Lithofacies (Minor): Basalt - andesite - dolerite - porphyrite dikes
• Sedimentary structures (Upper): Graded bedding, Reversed graded bedding, Wavy cross-stratification, Low angle cross-stratification
• Sedimentary structures (Lower): Platy joints, Columnar joints
• Sedimentary structures (Lower, Minor): Large-scale low angle cross-stratification, Bomb sag structure

• Mode of eruption (Lower, Minor): Phreatomagmatic
• Thickness: 80 - 1,200 m
• Thickness (Lower, Minor): 100 m or thicker
• Upper limit: Conformity (Fujina Formation)
• Lower limit: Unconformity (Kuri Formation, Kawai Formation)

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

• Distribution: Gotsu city - Oda city, Shimane pref.; Omori - Mount Kasenzan - Mount Wanoyama, Matsue city, Shimane pref.
• Fossils: Dicrocerus aff. furcatus, Paleoparadoxia tabatai, Sharks (Carcharodon megalodon), Foraminifera
• Fossils (Shellfishes): Anadara sp., Calliostoma simane, Clementia papyracea, Clinocardium shinjiense, Conchocele sp., Euspira sp., Fissidentalium yokoyamai, Glycymeris sp., Macoma sp., Mercenaria yokoyamai, Sinum yabei, Vasticardium sp.

• 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
• 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.)