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Nirasaki Debris Avalanche Deposits
Invalid synonym: Nirasaki Mudflow Deposit
- Type locality: Shichiriiwa, Nirasaki city, Yamanashi prefecture
- Coherent formation
- Sector collapse deposit of Yatsugatake volcano
- middle Pleistocene
- Sedimentary facies: Mudflow hills (more than 100 hills), Low temperature debris avalanche deposit
- Lithofacies: Breccia
- Source: Mount Gongendake of Yatsugatake volcano
- Thickness: 250 m or thicker
- Volume: ca. 9 km3
- Distribution (Mudflow hills, Diameter): 100 - 500 m
- Distribution (Mudflow hills, Height): 20 - 80 m
- Running distance: 40 km or more
- Upper limit: Unconformity (Hinoharu Formation, Kobozaka Pyroclastic Rocks, Shinanosakai Lava, Otakisha Lava, Kobuchizawa Formation, Higher Terrace Deposit, Middle Terrace Deposit)
- Lower limit: Unconformity (Kyoraishi Formation, Okkoto Lava, Southern Chichibu Belt)
------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown
- Distribution: Fujimi city - Kamanashi river - Hodokubo river - Takechi river, Suwa county, Nagano pref.; Sutama river, Hokuto city, Yamanashi pref.; Shichiriiwa, Nirasaki city, Yamanashi pref.; Mitsugigawa river, Kofu city, Yamanashi pref.
- Makimoto et al. (1996) Geology of the Takato District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 114p. (in Japanese with English abstract 6p.)
- Mimura et al. (1984) Geology of the Mitake-Shosenkyo District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 61p. (in Japanese with English abstract 4p.)
- Kawachi (1977) Geology of the Yatsugatake District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 92p. (in Japanese with English abstract 4p.)