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Aoki Formation Honma, 1931
In the Togakushi region, Redefined by dividing into Nishikyo Formation and Asakawa Formation in ascending order.
- Type locality: Kido - Shunara pass, Aoki city, Chiisagawa county, Nagano prefecture
- Coherent formation
- Miocene
- Correlation: Nishikyo Formation, upper Asakawa Formation
- Intruded by: Quartz diorite, Quartz porphyry
- Sedimentary facies: Marine
- Lithofacies (Top): Interbedded sandy mudstone and sandstone
- Lithofacies (Upper): Sandy mudstone
- Lithofacies (Upper, Minor): Sandy mudstone-dominant interbedded sandstone and mudstone
- Lithofacies (Middle): Sandstone, Conglomerate, Sandstone-dominant interbedded sandstone and mudstone
- Lithofacies (Lower): Sandy mudstone, Interbedded sandy mudstone and sandstone, Sandstone
- Lithofacies (Bottom): Conglomerate, Sandstone
- Sedimentary structures (Top): Load cast, Ripple marks, Slump structure, Cross stratification
- Sedimentary structures (Lower): Slump structure, Sole marks, Cross stratification
- Sedimentary structures (Bottom): Clastic dykes
- Thickness (Top): ca. 120 - 200 m
- Thickness (Upper): ca. 150 - 700 m
- Thickness (Middle): ca. 10 - 120 m
- Thickness (Lower): ca. 180 - 350 m
- Thickness (Bottom): ca. 100 - 300 m
- Upper limit: Lithofacies boundary (6.7 Ma)
- Upper limit: Conformity (Susobana Formation, Sashikiri Member), Unconformity (Older Josho Lake Deposit)
- Lower limit: Lithofacies boundary
- Lower limit: Conformity (Bessho Formation)
------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown
- Distribution: Kido - Shunara pass, Aoki city, Chiisagawa county, Nagano; Hitoeyama, Yashiro, Chikuma city, Nagano pref.; Kamiyamada - Tokura, Chikuma city, Nagano pref.; Shinkoji, Asakawa, Nagano city, Nagano pref.; Kawakamizawa, Ogawa city, Kamiminochi county, Nagano pref.; Kawanishi - Mount Okamiyama, Ueda city, Nagano pref.; Omigawa river, Omicity, Chikuma county, Nagano pref.; Akamatsu - Imai - Omigawa river, Chikuhoku city, Higashichikuma county, Nagano pref.; Kai, Ikusaka city, Higashichikuma county, Nagano pref.; Ishihara - Higashiotsuka, Yasaka, Omachi city, Nagano pref.
- Fossils: Sharks (Carcharhinus sp.), Echinoids (Sismondia naganoensis), Foraminifera
- Fossils (Trace fossils): Teredo sp.
- Fossils (Shellfishes): Acila divaricata, Acila submirabilis, Anadara amicula tazawensis, Anadara kurodai, Anadara makiyamai, Anadara minohensis, Anadara cf. setoensis, Anadara watanabei, Callista sp., Calyptraea tokunagai, Canceralia akashinensis, Cardium? sp., Chlamys sp., Coptothyris grayi, Cultellus asoensis, Cultellus otukai, Dentalium (Fissidentalium) yokoyamai, Diplodonta sp., Dosinia akaishiana, Dosinia chikuzenensis, Dosinia (Kaneharaia) kaneharai, Dosinia ovata, Felaniella usta, Fusinus sp., Fusitriton sp., Glycymeris k-suzukii, Glycymeris cf. vestitoides, Glycymeris yamazakii, Laevicardium angustum, Lucinoma acutilineata, Macoma incongrua, Macoma (Psammacoma) nipponica, Macoma tukyoensis, Margarites kurodai, Mercenaria shigaramiensis, Mercenaria y-iizukai, Nassarius nakamurai, Nassarius (Zeuxis) caelatus, Neptunea eos, Neptunea modesta, Neptunea paucicostatus, Neverita didyma, Neverita fissuratus, Nucula (Ennucula) akitana, Ocenebra kamabutensis, Ostrea sp., Palliolum (Delectopecten) peckhami, Panope japonica, Peronidea venulosa, Pitar okadana, Portlandia (Megayoldia) aokii, Portlandia (Megayoldia) yokouchii, Portlandia (Megayoldia) yotsukurensis, Portlandia (Portlandella) watasei, Protothaca sp., Sinum sp., Saccella confusa kongiensis, Saccella omorii, Siphonalia cf. s-nomurai, Solen tanosawaensis, Soletellina minoensis, Tectonatica janthostomoides, Tectura cf. asmiiformis, Tellina? sp., Trachycardium shiobarense, Trophonopsis sp., Yoldia uranoi
- Seki and Hoyanagi (2015) Jour. Geol. Soc. Japan, vol.121, no.8, pp.279-292, DOI
- Tanabe (2015) Jour. Geol. Soc. Japan, vol.121, no.8, pp.265-278, DOI
- Harayama et al. (2009) Geology of the Matsumoto District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 63p. (in Japanese with English abstract 3p.)
- Kato et al. (1989) Geology of the Omachi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 111p. (in Japanese with English abstract 7p.)
- Kato and Akahane (1986) Geology of the Nagano District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 120p. (in Japanese with English abstract 5p.)
- Kato and Sato (1983) Geology of the Shinano-Ikeda District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 93p. (in Japanese with English abstract 7p.)
- Kato (1980) Geology of the Sakaki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 57p. (in Japanese with English abstract 5p.)