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Tokurayama Formation (Ishibashi, 1986) Nagamori et al., 2010

Invalid synonym: Tokurayama Welded Tuff Member

• Type locality: Mount Tokurayama, Itoigawa city, Niigata prefecture
• Volcanic rocks
• Terrestrial felsic volcano
• Miocene (18.5 Ma, FT)
• Correlation: Shiraizawa Formation

• Sedimentary facies: Terrestrial
• Lithofacies: Rhyolite welded lapilli tuff, Lava
• Lithofacies (Basal): Tuffaceous volcanic conglomerate, Tuffaceous sandstone

• Thickness: ca. 100 - 700 m or thicker
• Thickness (Basal): 5 m or thicker
• Lower limit: Unconformity (Ishizaka Formation)

• Distribution: Mount Tokurayama - Downstream of Himekawa river - Mount Zenkojiyama - Mount Kamakurayama - Nakajoho, Itoigawa city, Niigata pref.

• Nagamori et al. (2010) Geology of the Kotaki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 130p. (in Japanese with English abstract 4p.)
• Takeuchi et al. (2010) Jour. Geol. Soc. Japan, vol.116, Supplement, pp.123-142 DOI