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Susobana Formation (Yamazaki, 1896) Saito, 1961
Invalid synonym: Susobana Tuff Member
It had been treated as a member of Ogawa Formation.
- Type locality: Susobana river, Minaminagano - Hirose, Nagano city, Nagano prefecture
- Volcanic rocks
- late Miocene (6.3 Ma, K-Ar; 7.5, 6.3, 6.1 Ma, FT)
- Correlation: Kinasa Tuff 10, Kinasa Tuff 20, Koso Tuff, Ndp Tephra, Kanaya Tuff Member
- Intruded by: Porphyrite, Augite-bearing hornblende hypersthene andesite (Mount Goroyama), Andesite dykes
- Sedimentary facies: Marine
- Sedimentary facies (Minor): Terrestrial
- Sedimentary facies (Upper): Volcaniclastic flow deposit
- Sedimentary facies (Lower): Lava dome, Reworked deposit
- Lithofacies (Top): Cummingtonite-bearing biotite hornblende rhyolite tuff
- Lithofacies (Upper): Cummingtonite-bearing biotite hornblende rhyolite pumice lapilli tuff
- Lithofacies (Middle): Sandstone, Conglomerate, Mudstone
- Lithofacies (Lower): Biotite rhyolite lava
- Lithofacies (Lower, Minor): Biotite rhyolite tuff breccia, Lapilli tuff
- Lithofacies (Minor): Mudstone
- Sedimentary structures (Top): Parallel stratification, Low-angle cross-stratification
- Source: In the vicinity of Shiozawa pass?
- Thickness: 0 - ca. 2,000 m
- Thickness (Upper): 700 - 800 m
- Thickness (Middle): 50 - 80 m
- Thickness (Lower): 1,000 - 1,100 m
- Upper limit: Conformity (Komiji Formation), Abut unconformity (Ronji Formation, Nishigawara Formation, Shinomiya Formation), Unconformity (Ogikubo Formation, Sarumaru Formation, Toyono Formation, Minamigo Formation, Kuwabara Volcanics, Hijiriyama Andesite, Kamuriki Formation, Mitsumineyama Volcanics, Akada Formation, Yanagisawa Mudflow Deposit, Older Obasute Mudflow Deposit)
- Lower limit: Conformity (Asakawa Formation, Aoki Formation, Shige Member)
------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown
- Distribution: Susobana river, Minaminagano - Hirose, Nagano city, Nagano pref.; Susobana river, Shinonoi, Nagano city, Nagano pref.; Momose, Konabe, Nagano city, Nagano pref.; Yubuku river - Komazawa river - Mount Katsurayama - Mount Motodoriyama, Nagano city, Nagano pref.; Saigawa river, Koichi - Hodama, Nagano city, Nagano pref.; Mosuge - Mount Chausu - Ishikawa - Shinomiya - Kosaka - Sano - Kori - Mine - Ubasute - Mount Fujinoto, Nagano city, Nagano pref.; Sasakyu - Ashinoshiri - Shiraisawa - Nakagome - Iriyama - Tsukudami, Ooka, Nagano city, Nagano pref.; Mount Kamuriki - Mount Azumayasan, Chikuhoku city, Higashichikuma county, Nagano pref.; Shijuhachimagari pass - Ichigosawa - Dorodaira, Omi city, Higashichikuma county, Nagano pref.; Sanseiji, Ikusaka city, Higashichikuma county, Nagano pref.
- Fossils: Silicified woods (Castanopsis makinoi)
- Tanabe (2015) Jour. Geol. Soc. Japan, vol.121, no.8, pp.265-278, DOI
- Sugito et al. (2015) Jour. Geol. Soc. Japan, vol.121, no.7, pp.217-232, DOI
- Nagamori et al. (2003) Geology of the Togakushi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 109p. (in Japanese with English abstract 3p.)
- Akahane et al. (1992) Geology of the Nakano District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 106p. (in Japanese with English abstract 4p.)
- Kato and Akahane (1986) Geology of the Nagano District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 120p. (in Japanese with English abstract 5p.)
- Kato and Sato (1983) Geology of the Shinano-Ikeda District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 93p. (in Japanese with English abstract 7p.)
- Kato (1980) Geology of the Sakaki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 57p. (in Japanese with English abstract 5p.)