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Shiramizu Group (Watanabe, 1926) Otuka, 1939

Invalid synonym: Uchigo Group

• Type locality: Uchigoshiramizu town, Iwaki city, Fukushima prefecture
• Coherent formation
• southern Yezo Forearc basin (Jobanoki basin)
• late Eocene - early Oligocene (Diatoms, Nannofossils, Pollen, Mammalia, Shellfishes)

• Sedimentary facies (Upper): Marine
• Sedimentary facies (Lower): Fluvial
• Sedimentary facies: Marine transgression sediments

• Thickness: ca. 350 - 600 m
• Upper limit: Unconformity (Yunagaya Group, Taga Group, Sodetamayama Formation)
• Lower limit: Unconformity (Asamigawa Member, Obisagawa Member, Kasamatsu Formation, Kohisagawa Member, Irimazawa Member, Seitarozawa Formation, Metamorphic rocks, Granitic rocks)

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

• Distribution: Kitazawa - Kamagasaki, Hirono city, Futaba county, Fukushima pref.; Itagizawa - Yamanota, Ohisa village, Iwaki city, Fukushima pref.; Uchigoshiramizu town, Iwaki city, Fukushima pref.

• Ando et al. (2011) Jour. Geol. Soc. Japan, vol.117, Supplement, pp.49-67 DOI
• Kubo et al. (2002) Geology of the Kawamae and Ide District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 136p. (in Japanese with English abstract 6p.)
• Kubo et al. (1994) Geology of the Namie and Iwaki-Tomioka District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 104p. (in Japanese with English abstract 7p.)
• Iwao and Matsui (1961) Taira and Kawamae, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 103p. (in Japanese with English abstract 17p.)