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Okaburi Formation (Fujimoto et al., 1957) Adachi et al., 1999

Invalid synonym: Okamuri Formation

• Volcanic rocks
• Volcanic collapse basin deposit
• late Miocene (6.8, 6.2 Ma, FT)
• Correlation: Konarayama Volcanic Rock
• Intruded by: Dacite dykes

• Lithofacies (Upper): Andesitic tuff breccia
• Lithofacies (Lower): Conglomerate
• Lithofacies (Minor): Andesitic Welded tuff

• Distribution: ca. 500 x 500 km²
• Lower limit: Abut unconformity (Nakatsugawa Group)

• Distribution: Okanmuri - confluence of the Nakatsugawa river and Mujinazawa creek - confluence of the Nakatsugawa river and Koshinzawa creek, Nakatsugawa, Chichibu city, Saitama pref.

• Hara et al. (2010) Geology of the Mitsumine District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 110p. (in Japanese with English abstract 4p.)