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Nk-MA Tephra Akutsu, 1957

Abbr.: Nk-MA

• Tephra
• late Pleistocene (ca. 0.1 Ma)

• Lithofacies (Upper): Volcanic ash
• Lithofacies (Lower): Scoriaceous lapilli

• Source: Nikko volcanos
• Mode of eruption: Plinian
• Host: Shimotsuke-Osawa Terrace Deposit, Shirasawa Terrace Deposit, Kamikake Terrace Deposit, Hoshakuji Loam, Kanuma Terrace Deposit
• Thickness: 13 - 60 cm or thinner

• Distribution: Lake Tsurugaike, Shimogo city, Minamiaizu county, Fukushima pref.; Nagano, Tajima, Minamiaizu city, Minamiaizu county, Fukushima pref.; Omuro - Noguchi, Nikko city, Tochigi pref.; Imaichi alluvial fan, Imaichi city, Tochigi pref.; Ishinada town, Utsunomiya city, Tochigi pref.

• Yoshikawa et al. (2010) Geology of the Utsunomiya District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 79p. (in Japanese with English abstract 6p.)
• Yamamoto (1999) Geology of the Tajima District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 85p. (in Japanese with English abstract 8p.)