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NA9 Tephra Tokuhashi, 1985

Abbr.: NA9

• Type locality: Nobe river, Ojiya city, Niigata prefecture
• Tephra
• Pliocene - Pleistocene (3.8, 2.72 Ma, FT)

• Lithofacies (Top): Pamice-bearing sandy siltstone
• Lithofacies (Upper): Rhyolite vitreous volcanic ash
• Lithofacies (Middle): Sandy volcanic ash
• Lithofacies (Lower): Pumiceous sandy volcanic ash

• Host: Minagawa Formation
• Thickness (Upper): 65 cm
• Thickness (Middle): 20 cm
• Thickness (Lower): 21 cm

• Distribution: Nobe river, Ojiya city, Niigata pref.; Shiroiwa, Nagaoka city, Niigata pref.

• Kobayashi et al. (1991) Geology of the Nagaoka District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 132p. (in Japanese with English abstract 6p.)
• Yanagisawa et al. (1986) Geology of the Ojiya District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 177p. (in Japanese with English abstract 6p.)