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Middle Unit

Abbr. So-OT pfd-m

A part of Shiobara-Shimogo Tephra Group

• Type locality: west Katamata, Yaita city, Tochigi prefecture
• Volcanic rocks
• Eruption products of a collapse caldera which formed Shiobara basin
• Pleistocene

• Lithofacies: Pumice flow deposit
• Lithofacies: Poorly sorted clast-supported pumiceous volcanic lapilli tuff
• Paleocurrent: West to East

• Source: Shiobara caldera
• Thickness (Tobanoyu hotspring): 36 m or thicker
• Thickness (Sawada): 30 m or thicker
• Thickness (Sekine, Kanawasaki): 20 m or thicker
• Thickness (Katamata): 10 m
• Thickness (Tobiyama): ca. 35 cm
• Thickness (Yanome): ca. 16 cm
• Lower limit: Conformity (Lower Unit)

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

• Distribution: Tobanoyu hotspring, Shioya city, Shioya county, Tochigi pref.; Katamata - Kanawasaki, Yaita city, Tochigi pref.; Sekine, Nasushiobara city, Tochigi pref.; Tobiyama, Takeshita town, Utsunomiya city, Tochigi pref.; Yanome, Toyohara-otsu, Nasu city, Nasu county, Tochigi pref.; Sawada, Shimogo city, Minamiaizu county, Fukushima pref.

• Yamada et al. (2018) Jour. Geol. Soc. Japan, vol.124, no.10, pp.837-855 DOI