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I Alternation of Sandstone and Mudstone Akahane, 1975

• Type locality: Nadachi river, Nadachi ward, Joetsu city, Niigata prefecture
• Coherent formation
• Rift basin sediments
• Miocene (? - 10.0 or 9.5 Ma)

• Sedimentary facies: Marine
• Sedimentary facies: Submarine fan (Sandy radial fan type)
• Sedimentary facies: Upper part of the 4th marine regression - transgression sequences
• Sedimentary facies: Muddy turbidite
• Lithofacies: Interbedded sandstone and mudstone
• Lithofacies (Minor): Glendonite
• Sedimentary structures: Groove marks, Flute marks, Slump structure

• Thickness: 200 - 400 m
• Upper limit: Conformity (J Alternation of Sandstone and Mudstone, Yokobatake Alternation of Sandstone and Mudstone Member)
• Lower limit: Conformity (H Alternation of Sandstone and Mudstone)

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

• Distribution: Nadachi river, Nadachi ward, Joetsu city, Niigata pref.; Kuwatori river - Nogawa river - Mount Shigekura, Joetsu city, Niigata pref.; Mount Aota-Nanbayama - Mount Awadachi, Myoko city, Niigata pref.; Hanareyama, Itoigawa city, Niigata pref.
• Fossils: Trace fossils
• Fossils (Shellfishes): Anadara sp., Chlamys sp., Chlamys cf. kaneharai, Clinocardium sp., Conchocele sp., Dentalium sp., Dosinia sp., Glycymeris sp., Ostrea sp., Portlandia sp., Siratoria cf. siratoriensis, Solernya cf. tokunagai

• Takano (2011) Jour. Geol. Soc. Japan, vol.117, no.4, pp.238-258 DOI
• 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.)