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Sarumaru Formation (Suzuki, 1938) Nagamori et al., 2003

Invalid Synonym: Sarumaru Sandstone Conglomerate Formation, Kawatani Formation, Kawatani Mudstone Formation

• Type locality: Ogikubo - Sarumaru, Togakushi, Nagano city, Nagano prefecture
• Coherent formation
• late Pliocene - early Pleistocene (1.7 - 1.6 Ma, FT)
• Correlation: Ogawa Formation, Hikage Formation, Joshita Member, Akada Formation
• Correlation (Upper): Minochi Formation
• Intruded by: Hornblende hypersthene augite Porphyrite

• Sedimentary facies (Upper): Braided river
• Sedimentary facies (Lower): Marine
• Lithofacies (Upper): Conglomerate
• Lithofacies (Upper, Minor): Sandstone, Mudstone, Felsic tuff
• Lithofacies (Lower): Sandstone
• Lithofacies (Lower, Minor): Conglomerate, Dacite - Rhyolite tuff
• Sedimentary structures (Upper): Cross stratification, Plant roots
• Sedimentary structures (Lower): Foreset cross-stratification, Wave ripples, Current ripples, Channel structure

• Thickness: ca. 40 - 750 m or thicker
• Thickness (Upper): 100 - 150 m
• Thickness (Lower): 100 - 150 m
• Upper limit: Unconformity (Hiderida Formation, Mure Debris Avalanche Deposit, Toyono Formation)
• Lower limit: Conformity (Takafu Formation, Minochi Formation, Tanogashira Formation), Conformity, partly unconformity (Ogikubo Formation), Abut unconformity (Susobana Formation, Arakurayama Formation)

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

• Distribution: Ogikubo - Osawa, Togakushi, Nagano city, Nagano pref.; Sarumaru - Nakagumi - Kamigumi, Togakushi, Nagano city, Nagano pref.; Kawatani, Toyono, Nagano city, Nagano pref.
• Fossils: Sirenia (Hydrodamaris sp.), Elephants (Stegodon shinshuensis), Foraminifera, Diatoms
• Fossils (Shellfishes): Crassostrea gigas, Cyclina sinensis, Macoma incongrua, Mya arenaria oonogai, Mya japonica, Natica sp., Tellina (Moerella) sp.
• Fossils (Plants): Metasequoia sp., Picea sp.
• Fossils (Pollen): Abies sp., Alunus sp., Betula sp., Carpinus sp., Carya sp., Fagus sp., Liquidambar sp., Ostrya sp., Pinus sp., Tsuga sp., Ulmus sp., Zelkova sp.
• Fossils (Trace fossils): Ophiomorpha isp.
• Tephra: T1, T2, T3, T3.5, T4, T5

• 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 et al. (1989) Geology of the Omachi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 111p. (in Japanese with English abstract 7p.)
• 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.)