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Tanosawa Formation Shibayama, 1929 ex Hanzawa et al.

Invalid synonym: Oirase Formation, Fukaura Formation

The host of bedded Mn deposits

• Type locality: Tanosawa - Kairagi - river mouth of Oirase river, Fukaura city, Nishitsugaru county, Aomori prefecture
• Coherent formation
• middle Miocene (17 - 16 Ma, Diatoms)
• Intruded by: Andesite dike, Rhyolite dike
• Correlation: Kurosaki Formation?

• Sedimentary facies: Shallow marine (Shellfishes, Diatoms, Foraminifera)
• Sedimentary facies: Lagoon, Bay, Open sea
• Sedimentary facies: Widely open bay
• Sedimentary facies: Transgressive
• Sedimentary facies: Submarine pyroclastic flow
• Water temperature: Warm (Foraminifera)
• Lithofacies: Conglomerate, Sandstone, Mudstone
• Lithofacies (Bottom): Basal conglomerate
• Lithofacies (Minor): Limestone, Rhyolitic - andesitic lapilli tuff, Pumice tuff, Tuffaceous sandstone

• Thickness: 100 - 1,000 m
• Upper limit: Conformity, partly unconformity (Odoji Formation), Conformity (Akaishi Formation)
• Lower limit: Unconformity (Kohamadatezawa Andesite Member, Azumagawa Rhyolite Member)

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

• Distribution: Tanosawa - Kairagi - river mouth of Oirase river, Fukaura city, Nishitsugaru county, Aomori pref.; Kitakanegasawa - Kodoji river - Odoji river, Fukaura city, Nishitsugaru county, Aomori pref.; Ojikari - Matsudai, Ajigasawa city, Nishitsugaru county, Aomori pref.; Hotate creek, Iwasaki, Fukaura city, Nishitsugaru county, Aomori pref.
• Fossils: Corals (Dendrophyllia koiwai), Silicified woods, Plants, Brachiopods, Sharks (Teeth)
• Fossils (Echinoids): Moira obesa, Astriclypeus ambigenus, Ehinolampas yoshiwara
• Fossils (Shellfishes): Acila yanagawaensis, Acmaea sp., Anadara kakehataensis, Anadara kurosedaniensis, Anadara cf. ninohensis, Anadara ogawai, Anadara sp., Anisocorbula? sp., Anomia cfr. cytaeum, Arca (Arca) sp., Calyptoraea tokunagai, Cancellaria spengleriana, Cardita sp., Cardium (Cerastoderma) shinjiense, Cardium (Trachycardium) sp., Cerithidea sp., Chama sp., Chicoreus sp., Chione? sp., Chlamys akitana, Chlamys arakawai, Chlamys cosibensis, Chlamys hataii, Chlamys heteroglyptus, Chlamys cf kaneharai, Chlamys cfr. islandious, Chlamys nisataiensis, Chlamys sp., Clementia brevitesta, Clementia cf. iizukai, Clinocardium cf. shinjiense, Dentalium tigillum, Dentalium weinkaufii, Dentalium yokoyamai, Dosinia akaishiana, Dosinia nomurai, Dosinia odosensis, Dosinia sp., Euspira meisensis, Glycymeris oinouyei, Glycymeris cfr. cisshuensis, Glycymeris vestitoides, Lima sp., Limopsis sp., Lucinoma acutilineatum (= Lucina (Myrtea) acutilineata), Lucinoma otukai, Lucinisca k-hataii, Macoma aomoriensis, Macoma incongrua, Macoma oinomikadoi, Macoma optiva, Macoma tokyoensis, Mactra (Spisula) sp., Mercenaria? sp., Mitra? sp., Mizuhopencten kimurai murayamai (= Patinopecten kimurai murayamai), Mizuhopecten kimurai ugoensis, Mizuhopecten yamazakii iwasakiensis, Murex tiganourana, Mya arenaria, Mya cuneiformis, Mya urushikuboana, Nassarius kometubus, Nassarius cf. notoensis, Natica (Tectonatica) janthostoma, Neilonella? sp., Nuculana confusa, Ostrea gravitesta, Ostrea musashiana, Ostrea rosacea, Ostrea sp., Panope japonica, Panope cf. kanomatazawaensis, Panomya simotomensis, Paphia hirabayashi, Patinopecten akihoensis, Patinopecten kimurai, Patinopecten nakajimai, Patinopecten cfr. paraplebejus, Patinopecten protomallitus, Pecten (Pallium) turpiculvs, Pecten (Pallium) swiftii, Pecten (Patinopecten) kimurai, Pecten (Patiopecten) yamasakii, Pecten (Pecten) arakawai, Pecten (Pecten) imasakiensis, Pecten ingeniosa, Pecten (Pecten) porotomollitus, Pedalion tugaruense, Pitar itoi, Placopecten nomurai, Placopecten protomollites, Pododesmus macroshisma, Protothaca tateiwai, Sakidomus giganteus, Saccella kongiensis, Serripes cf. shiobaraensis, Siliqua sp., Sinum yabei, Solen tanosawaensis, Tapes siratoriensis, Tellina? sp., Terebra sp., Thracia pertrapezoidea, Thracia sp., Thyasira nipponica, Turritella tanaguraensis, Venericardia ferruginea, Venericardia siogamensis, Venus (Chione) securis, Vicarya cf. callosa japonica, Yoldia (Cnesterium) sp.
• Fossils (Foraminifera): Operculina complanata, Operculina complanata japonica, Miogypsina kotoi, Robulus calcar, Nodosaria raphanus, Vaginulina bradyi, Vaginulina yoshihamaensis, Nonion kidoharaense, Nonion japonicum, Nonion nakosoensis, Nonion nicobarense, Rotalia cf. beccarii, Rotalia tochigiensis, Rotalia tanosawaensis, Rotalia beccarii hatatatensis, Rotalia japonica, Rotalia takanabenensis, Bolivina marginata, Bolivina robusta, Cassidulina laeirgata carinata, Cassidulina margareta, Cassidulina yabei, Cibicides aknerianus, Cibicides lobatulus, Cibicides pseudoungerianus, Cibicides cf. refulgens, Dentalina emaclata, Dentalina hyugaensis, Discopulirnulina bradyi, Discopulirnulina cf. nitida, Discopulirnulina sp., Discorbis? sp., Ellipsonodosaria hayasakai, Elphidiella momiyamaensis, Epistominella japonica, Eponides haidingeri, Eponides tanai, Eponides umbonatus, Globulina gibba, Guttulina baileyi, Gyroidina nipponica, Gyroidina orbicularis, Hanzawaia nipponica, Lagenodosaria fukushimaensis, Lagenodosaria scalaris sagamiensis, Marginnlina aculeata, Marginnlina sendaiensis, Planulina nipponica, Robulus iotus, Robulus pseudo-rotulatus, Sigmomorphina sp., Stilostomella cf. lepidula, Globigerina angustumbilicata, Globigerina bulloides, Globigerina concinna, Globigerina cf. diplostoma, Globigerina druryi, Globigerina juveniles, Globigerina praebulloides, Globigerina woodi, Globigerina sp. Globigerinella sp., Globigerinoides cyclostomus, Globigerinoides trilobus, Globorotalia fohsi barisanensis, Globorotalia scitula praescitula, Globorotaliloides variabilis
• Fossils (Diatoms, Marine): Actinocyclus ingens, Actinoptychus senarius, Amphora sp., Arachnoidiscus sp., Biddulphia cfr. pulchella, Clavicula polymorpha, Cocconeis scutellum, Cocconeis sp., Coscinodiscus nitidus, Coscinodiscus symbolophorus, Coscinodiscus sp., Cymatosira sp., Endictya aceanica, Diploneis smithii, Diploneis sp., Isthmia sp., Hyalodiscus obsoletus, Hyalodiscus ukaiensis, Kisseleviella carina, Mastogloia splendida, Melosira sol, Navicula spp., Paralia sulcata, Rhaphoneis, miocenica, Rhaphoneis spp., Rhizosolenia miocenica, Rhizosolenia spp., Rossiella sp., Stephanogonia cfr. hanzawae, Stephanopyxis sp., Synedra jouseana, Thalassionema nitzschioides, Thalassiothrix longissima, Trachyneis aspera
• Fossils (Diatoms, Freshwater): Aulacosira granulata, Cymbella sp., Surirella sp.

• Sakai et al. (2019) Jour. Geol. Soc. Japan, vol.125, no.4, pp.297-305 DOI
• Hirayama and Uemura (1985) Geology of the Ajigasawa District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 86p. (in Japanese with English abstract 6p.)
• Moritani (1968) Geology of the Fukaura District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 57p. (in Japanese with English abstract 5p.)