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Utto Formation Inoue, 1951
Invalid synonym: middle Aniai Formation, Koya Mudstone and Sandstone Member
- Type locality: Utto river, Hadachi, Nagahatake, Ani, Kitaakit city, Akita prefecture
- Volcanic rocks
- early Miocene (20 - 16 Ma; 19.8, 17.9, 16.4 Ma, FT; 18.2 Ma, K-Ar)
- Correlation: Makibuchi Formation
- Intruded by: Houzukiyama Dacite
- Lithofacies: Conglomerate, Sandstone, Mudstone
- Lithofacies (Minor): Dacite pumice volcanic lapilli tuff, Tuff, Basaltic andesite - andesite lava, Pyroclastic rocks
- Sedimentary structures: Parallel stratification
------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown
- Distribution: Utto river - Tsuyukuma creek - Nekko river - Arase river, Ani, Kitaakita city, Akita pref.; Iwanome creek - Shirasaki creek, Torisaka river, Ani, Kitaakita city, Akita pref.
- Fossils: Shellfishes (Unio? sp.)
- Fossils (Utto flora): Acer rotundatum, Actinodaphne oishii, Alangium aequalifolium, Alnus protomaximowiczii, Betula kamigoensis, Betula uzenensis, Buxus protojaponica, Calocedrus notoensis, Carpinus praejaponica, Castanea miomollissima, Castanea ungeri, Castanopsis miocuspidata, Cephalotaxus akitaensis, Cinnamomum lanceolatum, Cinnamomum miocenum, Cladrastis aniensis, Comptonia naumanni, Cyclobalanopsis mandraliscae, Cyclocarya ezoana, Cyclobalanopsis cfr. stuxbergi, Diospyros miokaki, Ehretia akitana, Fagus ferruginea, Fagus hayatae, Gleditsia miosinensis, Glyptostrobus europaeus, Ilex heeri, Ilex ohashii, Juglans shanwangensis, Lindera sp., Liquidambar formosana, Liquidambar miosinica, Machilus ugoana, Magnolia uttoensis, Marlea aequalifolia, Metasequoia occidentalis (= Metasequoia japonica), Paliurus miosinica, Parrotia fagifolia, Pinus sp., Podocarpus sp., Osmanthus sp., Picea sp., Pinus miocenica, Pseudotsuga cf. ezoana, Pterocarya sp., Quercus (Cyclobalanopsis) mandraliscae, Quercus miovariabilis, Quercus (Cyclobalanopsis) nathorstii, Quercus (Cyclobalanopsis) praegilva, Quercus subvariabilis, Smilax minor, Tripetaleia almqisti, Ulmus carpinoides, Ulmus longifolia, Ulmus protoparvifolia, Vibumum sp., Vitis sp., Wisteria fallax, Zelkova ungeri
- Kano (2018) Jour. Geol. Soc. Japan, vol.124, no.10, pp.781-803 DOI
- Kano et al. (2012) Geology of the Aniai District, 2nd Edition, 1:50,000 Quadrangle Series, Geological Survey of Japan, AIST, 59p. (in Japanese with English abstract 4p.)
- Ozawa and Sumi (1957) Moriyoshiyama, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 42p. (in Japanese with English abstract 5p.)