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Aso-4 Tephra

Abbr.: Aso-4

Synonym: Aso-4 Pyroclastic Flow Deposits, Aso-4B (pyroclastic flow deposit at the top)

• Volcanic rocks
• late Pleistocene (89 ka, K-Ar; 80 ka, U-Th; 86 - 90 ka, ¹⁸O)

• Lithofacies: Pyroclastic flow deposits

• Source: Aso caldera, Kumamoto pref., Japan
• Host: Katanishi Formation, Anden Sand Member, Kamiyama Loam, Sakayachi Formation, Shimosueyoshi Loam
• Thickness: 4 cm
• Upper limit: Unconformity (Yanagisawa Tuff)

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

• Distribution: all over Japan
• Distribution: Mashiki city, Kamimashiki county, Kumamoto pref.; Anden seashore, Oga city, Akita pref.; Futamata forest road, Tenei city, Iwase county, Fukushima pref.

• Ito et al. (2022) Geology of the Kiryu and Ashikaga District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 101p. (in Japanese with English abstract 4p.)
• Okuno (2019) Jour. Geol. Soc. Japan, vol.125, no.1, pp.41-53 DOI
• Nakazawa et al. (2018) Jour. Geol. Soc. Japan, vol.124, no.5, pp.347-359 DOI
• Ueki et al. (2013) Geology of the Hachioji District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 137p. (in Japanese with English abstract 6p.)
• Takagi et al. (2007) Jour. Geol. Soc. Japan, vol.113, no.1, pp.1-14 DOI
• Yamamoto (1999) Geology of the Tajima District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 85p. (in Japanese with English abstract 8p.)