[ Top ] [ Japanese ]

Oshi Pyroclastic Flow Deposit

Invalid synonum: Shirane Pumice Flow Deposit

• Tephra
• Pleistocene

• Lithofacies: Pyroclastic flow deposit
• Lithofacies: Andesite pumice tuff, Welded tuff

• Eruptive volume: 8 km³
• Thickness: 200 - 400 m
• Upper limit: Unconformity (Agatsuma Clay, Imai Gravels, Tsumagoi Pyroclastic Flow Deposit)
• Lower limit: Conformity or parallel unconformity (Kadokai Formation), Unconformity (Horaguchi Lava, Nittazawa Lavas, Kaminokai Lavas, Shirane Tuff Breccia)

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

• Distribution: Horaguchi, Naganohara city, Agatsuma county, Gunma pref.; Ogura - Tashirohara - Shinaki - Oshi - Namasu, Nakanojo city, Agatsuma county, Gunma pref.; Manza river - Akagawa river, Tsumagoi city, Agatsuma county, Gunma pref.

• Terada (2018) Jour. Geol. Soc. Japan, vol.124, no.4, pp.251-270 DOI
• Ota (1957) Kusatsu, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 75p. (in Japanese with English abstract 8p.)