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Mugurazawa Formation Chihara et al., 1981

• Type locality: Kiyotsu river, Mugurazawa Nakasato, Tokamachi city, Niigata prefecture
• Coherent formation
• Miocene (13.6, 12.7 Ma, FT)
• Intruded by: Basalt dikes
• Correlation: Shiiya Formation?, Akiyamago Formation?
• Correlation (Upper): Kakuma Sandstone and Mudstone Member
• Correlation (Middle): Tsuchikura Tuff Member = Tsuchikura Lapilli Tuff?
• Correlation (Lower): Koide Sandstone and Shale Member

• Sedimentary facies: Marine
• Lithofacies (Upper): Interbedded sandstone and shale, Lapilli tuff
• Lithofacies (Upper, Minor): Sandy tuff
• Lithofacies (Middle): Dacite tuff
• Lithofacies (Middle, Minor): Conglomerate, Sandstone, Siltstone
• Lithofacies (Lower): Sandstone-dominant interbedded tuffaceous sandstone and shale
• Lithofacies (Lower, Minor): Sand-bearing tuff, Conglomerate
• Sedimentary structures (Upper): Parallel stratification
• Sedimentary structures (Middle): Cross stratification
• Sedimentary structures (Lower): Parallel stratification

• Thickness: ca. 300 - 610 m or thicker
• Upper limit: Conformity (Nishitajiri Formation), Unconformity (Uonuma Formation)
• Lower limit: Conformity (Osawa Formation)

------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown

• Distribution: Kiyotsu river, Mugurazawa Nakasato, Tokamachi city, Niigata pref.; Mount Toma - Kama river - Shibakura creek - Mount Mitako - Kurashita, Tokamachi city, Niigata pref.

• Takeuchi et al. (2000) Geology of the Matsunoyama Onsen District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 76p. (in Japanese with English abstract 5p.)
• Shimazu and Tateishi (1993) Geology of the Naebasan District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 90p. (in Japanese with English abstract 5p.)
• 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.)
• Chihara et al. (1981) Geology of the Echigo-Yuzawa District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 108p. (in Japanese with English abstract 8p.)