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Nanatani Formation (Watanabe, 1928) Kudo et al., 2011

Invalid synonym: Kannonji Formation

• Type locality (Previous): Otani, Kamo city (previous Nanatani village), Niigata prefecture
• Type locality (Re-defined): Komade river - Harai river, Kitaimogawa, Shitada, Sanjo city, Niigata prefecture
• Coherent formation
• middle Miocene (ca. 15.2 - 12.3 Ma; 14.6, 12.8 Ma, FT; 14.7 - 14.2 Ma, Nannofossils)
• Correlation: Numazawa Formation, Awashima Shale Member, Hanzogane Formation, Nishimyo Formation, Jyunitoge Green Tuff Member, Ketto Formation
• Intruded by: Rhyolite, Dolerite, Basalt, Andesite

• Sedimentary facies: Marine
• Water temperature: Warm ocean current
• Depth of water: Bathyal (Benthonic foraminifera)
• Lithofacies (Top): Glauconite sandstone
• Lithofacies (Upper): Mudstone, Shale
• Lithofacies (Lower): Basalt - Andesite tuff breccia, Lapilli tuff, Rhyolite volcanic breccia, Tuff breccia, Lapilli tuff, Tuff
• Lithofacies (Lower, Minor): Mudstone

• Thickness: ca. 300 - ca. 800 m
• Upper limit: Top of the glauconite sandstone bed
• Upper limit: Conformity (Teradomari Formation, Nambayama Formation, Minamiimogawa Formation)
• Lower limit: Conformity (Otani Formation), Unconformity (Basement)

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

• Distribution: Komade river - Harai river, Kitaimogawa, Shitada, Sanjo city, Niigata pref.; Shionobuchi, Sanjo city, Niigata pref.; Otani - Nanatani, Kamo city, Niigata pref.; Mount Kugami, Tsubame city, Niigata pref.; Kamitokura, Gosen city, Niigata pref.
• Fossils: Foraminifera, Calcareous nannofossils, Dinoflagellates
• Fossils (Radiolarians): Cannartus violina, Cycladophora favosa, Stichocorys delmontensis
• Fossils (Diatoms): Actinocyclus inges f. nodus, Denticulopsis hyalina, Denticulopsis ichikawae, Denticulopsis lauta, Denticulopsis praedimorpha var. minor, Denticulopsis simonsenii, Denticulopsis vulgaris
• Tephra: Kws, Kbi, Kzi, Kkm, Khs, Kpp, Sbi

• Kudo et al. (2011) Geology of the Kamo District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 162p. (in Japanese with English abstract 4p.)
• Kudo et al. (2011) Jour. Geol. Soc. Japan, vol.117, no.5, pp.277-288 DOI
• Takano (2011) Jour. Geol. Soc. Japan, vol.117, no.4, pp.238-258 DOI
• Kobayashi et al. (2010) Jour. Geol. Soc. Japan, vol.116, no.11, pp.XVII-XVIII
• Hiranaka et al. (2009) Jour. Geol. Soc. Japan, vol.115, no.4, pp.177-186 DOI
• Kobayashi et al. (2002) Geology of the Sanjo District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 98p. (in Japanese with English abstract 4p.)
• Yanagisawa et al. (2000) Geology of the Iiyama District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 144p. (in Japanese with English abstract 6p.)