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Sogo Formation (Shiida and Shibata, 1968)
Invalid synonym: upper Oyamado Formation, Sotonohashi Member, Shizumi Member
- Type locality: Sogo, Tsuge, Nara city, Nara prefecture
- Coherent formation
- Miocene (17.7 Ma, FT)
- Sedimentary facies: Marine
- Sedimentary facies: Coastal
- Depth of water: Upper sublittoral
- Lithofacies (Upper): Interbedded sandstone and siltstone
- Lithofacies (Upper, Minor): Dacite tuff
- Lithofacies (Middle): Conglomerate
- Lithofacies (Middle, Minor): Sandstone
- Lithofacies (Lower): Sandstone
- Lithofacies (Lower, Minor): Conglomerate
- Sedimentary structures (Upper): Parallel stratification, Cross stratifiction
- Sedimentary structures (Middle): Imbricate structure
- Sedimentary structures (Lower): Parallel stratification, Cross stratifiction
- Paleocurrent: to South-southeast
- Thickness: ca. 100 - 120 m
- Thickness (Upper): 40 m
- Thickness (Middle): 20 - 50 m
- Thickness (Lower): 0 - 40 m
- Upper limit: Transitional (Hayama Formation)
- Lower limit: Transitional (Iu Formation), Unconformity
------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown
- Distribution: Sogo - Hayama - Oyamato - Nagano - Minaminosho - Shiraichi, Tsuge, Nara city, Nara pref.; Iu town, Nara city, Nara pref.; Kaminyuda - Minoda - Inoichi, Tenri city, Nara pref.; Mukoji - Okubo - Nukai - Tenmadai, Uda city, Nara pref.; Mount Mahirayama - Mount Kaigahirayama, Sakurai city, Nara pref.
- Fossils: Bryozoans
- Fossils (Shellfishes): Cavolina sp., Chlamys sp., Dosinia (Phacosoma) kawagensis, Glycymeris cisshuensis, Lucinoma acutilineatum, Macoma izurensis, Macoma optiva, Mytilus sp., Ostrea (Crassostrea) gigas, Siphonalia minuts, Tectonatica sp., Thyasira sp., Turritella sagai
- Fossils: Ophiomorpha isp.
- Sato et al. (2012) Jour. Geol. Soc. Japan, vol.118, Supplement, pp.53-69 DOI
- Nishioka et al. (2001) Geology of the Sakurai District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 141p. (in Japanese with English abstract 5p.)
- Nishioka et al. (1998) Geology of the Nabari District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 72p. (in Japanese with English abstract 5p.)