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Ryugamine Lavas

• Type locality: Mount Ryugamine, Hakkano, Ashida, Tateshina city, Kitasaku county, Nagano prefecture
• Volcanic rocks
• early Pleistocene (1.02 - 0.95 Ma, K-Ar)

• Lithofacies: Hypersthene augite andesite lavas (7 flow units), Pyroclastic rocks

• Source: West of Mount Tateshina, uppermost reaches of Kakuma river
• Eruptive volume: 4.1 km³
• Thickness (Overall): 30 - 200 m
• Thickness (A unit): 10 - 30 m
• Distribution (Width): 3.5 km
• Running distance: 7 km or more
• Upper limit: Unconformity (Maetateshinayama Lava)
• Lower limit: Unconformity (Uyamasegi Lava, Amazakai Pyroclastic Flow Deposit, Hosokojigawa Lava)

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

• Distribution: Mount Ryugamine - Amazakai - Uyamazeki - Akanumadaira, Tateshina city, Kitasaku county, Nagano pref.; Omozawa river, Nagawa city, Chiisagawa county, Nagano pref.; Ogawara pass, Saku city, Nagano pref.

• Nishiki and Takahashi (2012) Jour. Geol. Soc. Japan, vol.118, no.8, pp.499-515 DOI
• Kawachi and Aramaki (1979) Geology of the Komoro District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 39p. (in Japanese with English abstract 2p.)
• Kawachi (1974) Geology of the Tateshinayama District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 114p. (in Japanese with English abstract 5p.)