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Sugawa Formation Niigata University Reseach Group of Geology in Higashikubiki District, 1987

Takeuchi et al. considered Sugawa Formation is a part of Takegahana Formation.

Invalid synonym: Yokozumi Formation, Kiwadahara Formation

• Type locality: Sugawa river, Shinanozaka - Sugawa, Yasuzuka ward, Joetsu city, Niigata prefecture
• Coherent formation
• Rift basin sediments
• late Miocene - early Pliocene (ca. 6 - 5 Ma)
• Contemporaneous heterotopic facies (Lower): upper Taruda Formation
• Correlation: Shiiya Formation, Kakuma Formation, Tomikura Formation
• Intruded by: Augite hypersthene andesite, Hypersthene andesite

• Sedimentary facies: Marine
• Depth of water: Deeper
• Lithofacies: Mudstone
• Lithofacies (Lower): Mudstone-dominant interbedded mudstone and sandstone, Acidic tuff

• Thickness: 300 - 2,000 m
• Upper limit: Bottom of interbedded sandstone and mudstone overlying mudstone bed
• Upper limit: Transitional (Tamugigawa Formation), Unconformity (Saruhashi Conglomerate Member)
• Lower limit: Transitional (Taruda Formation)

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

• Distribution: Sugawa river - Funakura river, Yasuzuka ward, Joetsu city, Niigata pref.; Ishidani, Yoshikawa ward, Joetsu city, Niigata pref.; Uragawara ward, Joetsu city, Niigata pref.; Mine, Oshima ward, Joetsu city, Niigata pref.; Ono, Takayanagi town, Kashiwazaki city, Niigata pref.; Hokura river, Joetsu city, Niigata pref.; Murono, Tokamachi city, Niigata pref.
• Fossils: Baleen whales, Echinoids, Sponges (Makiyama chitanii)
• Fossils (Shellfishes): Calyptogena sp., Conchocele bisecta, Mizuhopecten yokoyamai, Mya sp.
• Fossils (Foraminifera): Alabamina? sp., Ammodiscus sp., Baggina totomiensis, , Bolivina decussata, Bolivinita quadrilatera, Buccella inusitata, Bulimina striata, Cassidulina japonica, Cassidulina norcrossi, Cassidulina norvangi, Cassidulinoides sp., Chilostoniella oolina, Cibicides aknerianus, Cibicides pseudoungerianus, Cribroelphidium yabei, Cribrononion clavatum, Cribrononion subglanulosum, Cribrostomoides renzi, Cribrostomoides cf. subglobosum, Cyclammina pusilla, Discammina sp., Discorbis sp., Eilohedra nipponica, Elphidium sp., Epistominella exiqua, Epistominella levicula, Epistominella naraensis, Epistominella pulchella, Fissurina marginata, Fissurina orbignyana, Furusenkoina complanata, Gavelinopsis cf. peregrina, Glandulina sp., Globigerina bulloides, Globigerina cf. falconensis, Globigerina praebulloides, Globigerina quinqueloba, Globigerinita glutinata, Globigerinita uvula, Globigerinoides ruber, Globobulimina auriculata, Globocassidulina depressa, Globocassidulina subglobosa, Globorotalia orientalis, Globorotalia praeinflata, Guttina sp., Haplophragmoides compressum, Islandiella norvangi,Islandiella aff. sublimbata, Islandiella yabei, Karreriella japonica, Lagena sp., Loxostoma bradyi, Martinottiella communis, Melonis cf. nicobarense, Melonis pompilioides, Miliammina echigoensis, Neogloboquadrina aff. acostaensis, Neogloboquadrina cf. asanoi, Neogloboquadrina blowi, Neogloboquadrina eggeri, Neogloboquadrina cf. himiensis, Neogloboquadrina cf. kagaensis, Neogloboquadrina pachyderma, Nodosaria sp., Nonion sp., Nonionella stella, Nonionellina labradricum, Oolina hexsagana, Orbulina universa, Oridosalis tenerus, Oridosalis umbonatus, Pseudoparrella takayanagii, Pullenia apertula, Quinqueloculina sp., Rosalina sp., Saccammina sp., Sigmodopsis sp., Silicosigmoilinella sp., Sphaeroidinella bulloides, Sphaeroidinella cf. japonica, Trifarina kokozuraensis, Triloclina tricarinata, Trochammina spp., Uvigerina akitaensis, Uvigerina cf. subperegina, Valvulineria sadonica
• Fossils (Diatoms): Actinocyclus octonarius, Actinoptychus senarius, Arachnoidiscus sp., Aulacoseira spp., Cocconeis costata, Cocconeis scutellum, Cocconeis vitrea, Coscinodiscus marginatus, Coscinodiscus radiatus, Cyclotella striata, Delphineis surirella, Diploneis smithii, Grammatophora spp., Navicula sp., Paralia sulcata, Plagiogramma starophorum, Stellarima microtrias, Stephanopyxis spp., Thalassionema nitzschioidees, Thalassiosira marujamica, Thalassiosira nidulus, Thalassiosira temperei
• Tephra: Kiwadahara Tuff, Takatoko Tuff, Tt4, Tani Tuff, Amamizukoshi Tuff

• Kakizaki et al. (2018) Jour. Geol. Soc. Japan, vol.124, no.2, pp.127-140 DOI
• Takano (2011) Jour. Geol. Soc. Japan, vol.117, no.4, pp.238-258 DOI
• Takeuchi et al. (2000) Geology of the Matsunoyama Onsen District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 76p. (in Japanese with English abstract 5p.)
• Takeuchi and Kato (1994) Geology of the Takada-tobu District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 67p. (in Japanese with English abstract 5p.)
• Kobayashi et al. (1989) Geology of the Okanomachi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 112p. (in Japanese with English abstract 5p.)