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Iwai Formation Nishioka et al., 2001

Invalid synonym: lower Iwabuchi Formation

• Type locality: Iwaigawa river, Nara city, Nara prefecture
• Coherent formation
• Miocene

• Lithofacies: Conglomerate
• Lithofacies (Minor): Breccia, Siltstone, Sandstone, Lignite

• Thickness: ca. 20 - 100 m
• Upper limit: Conformity (Kokuzo Formation)
• Lower limit: Unconformity (Ryoke Metamorphic Rocks, Granite)

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

• Distribution: Iwaigawa river - Rokuyaon town - Fujiwara town - Takahi town - Kokuzo town - Yashima town - Bodaisen town, Nara city, Nara pref.; Shirakawa dam - Iwaya town - Toyoda town - Isonokami shrine - Furu town, Tenri city, Nara pref.

• 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.)