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Numazawa Formation (Morita, 1930 ex Yabe and Hatai, 1941) Yanagisawa and Yamamoto, 1998

Invalid synonym: Rokutozawa Formation, Ohanayama Andesites, Taruguchi Formation, Arao Formation, Maze Shale and Tuff Member, Kusaitoge Formation, Tsunakigawa Formation, Onogawa Formation

• Type locality: Shirakozawa - Osogoshi, Numazawa, Oguni city, Nishiokitama county, Yamagata prefecture
• Coherent formation
• middle Miocene (Foraminifera, Calcareous nannofossils)
• Contemporaneous heterotopic facies (Upper): Tsuchiyutoge Formation, Ninosawa Formation
• Correlation: Nanatani Formation, Nishikurosawa Formation, Funato Formation, Oishigawa Formation, Shimoseki Formation
• Intruded by: Andesite dike, Dolerite dike
• Intruded by (Lower): Rhyolite dike

• Sedimentary facies: Marine
• Sedimentary facies: Shallow marine in the open sea, Inner bay (Shellfishes)
• Sedimentary facies (Bottom): Shallow marine
• Sedimentary facies (Lower): Lava domes
• Depth of water: ca. 60 m, at least deeper than 30 m
• Lithofacies (Upper): Mudstone
• Lithofacies (Upper, Minor): Andesite - Basalt lava, Pyroclastic rocks, Rhyolite pyroclastic rocks
• Lithofacies (Lower): Interbedded mudstone and sandstone, Mudstone
• Lithofacies (Lower, Minor): Rhyolite lava, Volcanic conglomerate, Volcanic sandstone, Lapilli tuff, Tuff breccia, Basalt scoria, Lapilli stone
• Lithofacies (Bottom): Volcanic sandstone
• Sedimentary structures (Lower): Parallel stratification, Low angle cross stratification

• Thickness: ca. 400 - 1,150 m
• Upper limit: Bottom of the horizon composed of dark black mudstone, Top of the rhyolitic pyroclastic rocks.
• Upper limit: Transitional (Yugoya Formation)
• Lower limit: Bottom of shellfish fossil-bearing calcareous sandstone or tuffaceous sandstone showing cross stratification
• Lower limit: Conformity (Myozawabashi Formation)

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

• Distribution: Numazawa - Kanomizu - Kotaru river, Oguni city, Nishiokitama county, Yamagata pref.
• Fossils: Brachiopods (Coptothyris grayi), Barnacles, Plants, Foraminifera, Calcareous nannnofossils, Bryozoans
• Fossils (Shellfishes): Anadara (Scapharca) sp., Barbatia? sp., Batillaria sp., Certhideopsilla sp., Chlamys cf. arakawai, Chlamys cf. nisataiensis, Clementia sp., Crassostrea gravitesta, Euspira sp., Kotorapecten kagamianus permirus, Mizuhopecten kimurai murayamai, Ostrea gravitesta, Panopea nomurae, Patinopecten sp., Phacosoma akaishiana, Placopecten nomurai
• Fossils (Foraminifera): Globigerina concinna, Globigerina praebulloides, Globigerina woodi, Globigerinita glutinata, Globigerinoides quadrilobatus immaturus, Globigerinoides trilobus, Globoquadrina altispira altispira, Globoquadrina dehiscens advena, Globoquadrina dehiscens dehiscens, Globoquadrina venezuelana, Globorotalia birnageae, Globorotalia conoidea, Globorotalia peripheroacuta, Globorotalia quinifalcata, Globorotalia siakensis, Orbulina suturalis, Orbulina universa, Sphaeroidinellopsis seminulina, Velapertina cingulata
• Fossils (Calcareous nannofossils): Calcidiscus leptoporus, Calcidiscus macintyrei, Coccolithus miopelagicus, Coccolithus pelagicus, Coronocyclus nitescens, Cyclicargolithus floridanus, Discoaster adamanteus, Discoaster deflandrei, Discoaster exilis, Discoaster intercalaris, Discoaster variabilis, Helicosphaera carteri, Helicosphaera euphratis, Reticulofenestra gartneri, Reticulofenestra heslandii, Reticulofenestra pseudoumbilica, Sphenolithus abies, Sphenolithus heteromorphus, Sphenolithus moriformis, Sphenolithus neoabies, Thoracosphaera deflandrei

• Furukawa et al. (2018) Geology of the Azuma Yama District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 74p. (in Japanese with English abstract 3p.)
• Yamanoi et al. (2008) Jour. Geol. Soc. Japan, vol.114, no.5, pp.262-266 DOI
• Yanagisawa and Yamamoto (1998) Geology of the Tamaniwa District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 94p. (in Japanese with English abstract 4p.)
• Takahashi et al. (1996) Geology of the Iidesan District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 52p. (in Japanese with English abstract 3p.)