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Obg Tephra Kurokawa et al., 1987

Abbr.: Obg

• Type locality: Yamada, Teradomari, Nagaoka city, Niigata prefecture
• Tephra
• middle Miocene - early Pliocene

• Lithofacies (Upper): Silt-size vitreous tephra
• Lithofacies (Lower): Sand-size vitreous tephra
• Sedimentary structures: Graded bedding

• Thickness (Upper): 10 cm
• Thickness (Lower): 3 cm
• Host: Shiiya Formation

• Distribution: Yamada, Teradomari, Nagaoka city, Niigata pref.

• Kobayashi et al. (1993) Geology of the Izumozaki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 91p. (in Japanese with English abstract 4p.)