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Nakawatari Formation (Hanzawa et al., 1958) Moriya et al., 2008

Invalid synonym: Ashizawa Formation

• Type locality: Nakawatari, Sakegawa city, Mogami county, Yamagata prefecture
• Coherent formation
• Pliocene (? - 4.3 Ma, FT)
• Correlation: Upper Tateyama Formation

• Sedimentary facies (North, Center): Marine
• Sedimentary facies (South): Fluvial
• Sedimentary facies (North): Outer shelf, Continental slope
• Sedimentary facies (Center): Fore shore, Inner shelf
• Lithofacies (North): Mudstone
• Lithofacies (Center): Sandstone
• Lithofacies (South): Interbedded sandstone and mudstone
• Lithofacies (South, Minor): Lignite
• Sedimentary structures: Cross stratification
• Paleocurrent: North - Northwest

• Thickness: ca. 200 - 300 m
• Upper limit: Conformity (Sakekawa Formation)
• Upper limit (North): Bottom of NG Tephra
• Upper limit (Center): Bottom of interbedded sandstone and mudstone beds
• Upper limit (North): Bottom of Sandstone bed
• Lower limit (North, Center, Southwest): Conformity (Noguchi Formation)
• Lower limit (South): Unconformity (Noguchi Formation)
• Lower limit (Center, Southwest): Bottom of sandstone bed
• Lower limit (South): Bottom of lignite bed

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

• Distribution: Nakawatari - Ashizawa - Kinonezaka, Sakegawa city, Mogami county, Yamagata pref.; Osawa, Mamurogawa city, Mogami county, Yamagata pref.
• Fossils: Diatoms, Plants, Barnacles, Echinoids (Linthia nipponica)
• Fossils: Omma-Manganji fauna: Acila (Truncacila) cf. nakazimai, Buccinum magarikawaensis, Bucciun cf. opisthoplectum, Chlamys cf. imanishii, Clinocardium chikagawaense, Clinocardium fastosum, Clinocardium cf. nuttalli, Conchocele bisecta, Fulgoraria magna, Fusitoriton sp., Glycymeris yessoensis, Limatula kurodai, Lucinoma acutilineata, Macoma calcarea, Macoma incongura, Macoma tokyoensis, Mercenaria stimpsoni, Mizuhopecten cf. yessoensis, Mya cuneiformis, Mya (Mya) japonica, Nemocardium (Keenaea) samarangae, Neptunea intersculpta, Neptunea nikkoensis, Neverita cf. didyma, Parancistrolepis cf. fujitai, Peronidia cf. lutea, Rectiplanes sanctiioannis, Serripes groenlandicus, Siphonaemea cf. oblongata, Solemya tokunagai, Solomon spectabilis, Tectonatica janthostomoides, Teredo sp., Thracia cf. kakumana, Turritella fortilirata, Vasticardium sp., Yabepecten tokunagai, Yoldia (Cnesterium) notabilis
• Fossils (Foraminifera): Anomalinoides globrata, Buccella sp., Cibicides aknerianus, Epistominella pulchella, Florilus sp., Guttulina yabei, Haplophragmoides sp., Islandiella californica, Islandiella norcrossi, Lenticulina sp., Melonis pompilioides, Nonionella sp., Orbulina universa, Polymorphina charlottensis, Pullenia salisburyi, Sigmomorphina sawanensis, Uvigerina peregrina, Uvigerina yabei
• Fossils (Nannofossils): Cocolithus pelagicus, Crenalithus doronicoides
• Tephra: TT-1

• Moriya et al. (2008) Jour. Geol. Soc. Japan, vol.114, no.8, pp.389-404 DOI
• Moriya et al. (2008) Jour. Geol. Soc. Japan, vol.114, no.1, pp.1-15 DOI
• Tsuchiya (1989) Geology of the Osawa District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 85p. (in Japanese with English abstract 6p.)