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Tsutsuishi Alternation of Sandstone and Mudstone Member (Fujimoto, 1951) Akahane and Kato, 1989

• Type locality: Tsutsuishi - Hamatokuai, Itoigawa city, Niigata prefecture
• Coherent formation
• Rift basin sediments
• Pliocene
• Interfingered: Iwaobashi Sandstone Member, Tsunako Conglomerate Member
• Contemporaneous heterotopic facies: Nagahama Mudstone Member

• Sedimentary facies: Marine
• Lithofacies: Sandstone-dominant interbedded sandstone and mudstone, Mudstone
• Lithofacies (Minor): Conglomerate, Gravel-bearing mudstone, Sandstone, Andesite lava, Tuff breccia

• Thickness: 150 - 400 m
• Upper limit: Conformity (Nadachi Formation), Unconformity (Eboshiyama Volcanic Rocks)
• Lower limit: Conformity (Seto Tuff Member, Iwaobashi Sandstone Member)

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

• Distribution: Tsutsuishi - Hamatokuai - Kawazume - Takakura, Itoigawa city, Niigata pref.; Doguchi, Joetsu city, Niigata pref.
• Fossils: Sponges (Makiyama chitanii)
• Fossils (Shellfishes): Acila sp., Anadara amicula elongata, Clinocaridum sp., Conchocele bisseeta, Cryptonatica sp., Glycymeris yessoensis, Mizuhopecten yessoensis, Nuculana (Testyleda) yokoyamai, Turritella sp.

• Akahane and Kato (1989) Geology of the Takada-Seibu District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 89p. (in Japanese with English abstract 3p.)