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Akashima Formation (Fujioka et al., 1954) Fujioka, 1959

• Type locality: near Akashima island, Toga, Oga city, Akita prefecture
• Caldera?
• Volcanic rocks
• Late Cretaceous (72.0 Ma, U-Pb; 65 - 59 Ma, FT)

• Sedimentary facies: Marine
• Lithofacies: Orthopyroxene-clinopyrocene dacite
• Lithofacies (Upper): Welded pyroclastic rocks
• Lithofacies (Lower, Main): Volcanic breccia
• Lithofacies (Lower, Minor): Granite blocks

• Thickness: 200 m or thicker
• Upper limit: Unconformity (Nishikurosawa Formation)
• Lower limit: Unconformity (Hornblende biotite granite)

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

• Distribution: Cape Nyudo - Hatake, Kitaura, Oga city, Akita pref.; Akashima island, Toga, Oga city, Akita pref.

• Kano (2018) Jour. Geol. Soc. Japan, vol.124, no.10, pp.781-803 DOI
• Kano et al. (2012) Jour. Geol. Soc. Japan, vol.118, no.6, pp.351-364 DOI
• Kano et al. (2011) Geology of the Toga and Funakawa District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 127p. (in Japanese with English abstract 4p.)
• Kobayashi et al. (2010) Jour. Geol. Soc. Japan, vol.116, no.10, pp.552-562 DOI
• Ohguchi et al. (2008) Jour. Geol. Soc. Japan, vol.114, Supplement, pp.17-32 DOI
• Fujimoto et al. (2008) Jour. Geol. Soc. Japan, vol.114, Supplement, pp.51-74 DOI