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Hiwada Formation Yamamoto, 1992
Invalid synonym: Hiwada Conglomerate Member, Mikuizawa? Formation, Nakayashiki Sandstone, Mudstone and Conglomerate Member
- Type locality: Higashiomata river, Hiwada, Aizumisato city, Onuma county, Fukushima prefecture
- Volcanic rocks
- Collapse caldera-fill deposit
- Pliocene
- Tonalite: Miocene (3.5 Ma, K-Ar)
- Sedimentary facies: Lacustrine
- Lithofacies (Lacustrine): Sandstone, Conglomerate, Siltstone, Dacite pumice lapilli tuff
- Lithofacies (Intrusive rocks): Biotite hornblende tonalite, Rhyolite, Diolite porphyry, Granodiorite porphyry
- Lithofacies (Debris avalanche): Breccia
- Sedimentary structures (Lacustrine): Graded bedding, Reversed graded bedding, Parallel stratification
- Hiwada Formation
- [ Upper ]
- ~~~~~~~~~~~~~~
- Lacustrine deposit / Intrusive rocks = Post-caldera stage
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- Hotokezawa Pyroclastic Flow Deposit / Debris avalanche deposit = Caldera-forming stage
- ~~~~~~~~~~~~~~
- [ Lower ]
- Hiwada caldera
- [ Upper ]
- ~~~~~~~~~~~~~~
- Hiwada Formation
- ~~~~~~~~~~~~~~
- [ Lower ]
------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown
- Distribution: Higashiomata river, Hiwada, Aizumisato city, Onuma county, Fukushima pref.; Kuwatobi - Yokoyama, Shimogo city, Minamiaizu county, Fukushima pref.; Miyagawa dam, Aizumisato city, Onuma county, Fukushima pref.
- Fossils (Plants): Berchemia miofloribunda, Cladrastis aniensis, Ostrya cfr. aizuana, Rhus protoambingua
- Yamamoto (1999) Geology of the Tajima District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 85p. (in Japanese with English abstract 8p.)
- Yamamoto and Yoshioka (1992) Geology of the Wakamatsu District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 73p. (in Japanese with English abstract 5p.)