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OM1-OK III Tephra (Yanagisawa et al., 1985)

Abbr.: OM1-OK III

Invalid synonym: SR

• Type locality: Tagawa river, Tokamachi city, Niigata prefecture
• Type locality (MY): Matsubeyamada, Katsuura city, Chiba prefecture
• Tephra
• Pleistocene (2.15 Ma)
• Correlation: MY, Ogy (Takayama, Gifu), OM1 (Kanazawa, Ishikawa), OikeIII (Tokamachi, Niigata), Se

• Lithofacies (Upper): Volcanic ash
• Lithofacies (Lower): Interbedded volcanic ash and vitreous volcanic ash
• Sedimentary structures (Upper): Cross stratificaiton

• Source: Chubu mountains, Japan
• Host: Uonuma Formation, Namihana Formation
• Thickness (MY): 5 - 6 cm

• Distribution: Tagawa river, Tokamachi city, Niigata pref.

• Tamura et al. (2019) Jour. Geol. Soc. Japan, vol.125, no.1, pp.23-39 DOI
• Yanagisawa et al. (1985) Geology of the Tokamachi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 104p. (in Japanese with English abstract 6p.)