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Yabashirazawa Lavas (Kawachi, 1974-75) Nishiki et al., 2007

Abbr.: YZ

• Type locality: 1,500 m above sea level of Yabashira creek, Sakuho city, Minamisaku county, Nagano prefecture
• Volcanic rocks
• early Pleistocene (1.00 Ma, K-Ar)

• Lithofacies: Hornblende orthopyroxene clinopyroxene dacite
• Lithofacies: Lavas (3 flow units)
• Lithofacies (Minor): Scoria, Agglomerate, Volcanic breccia

• Source: Mount Yabashira
• Eruptive volume: 0.4 km³
• Thickness: ca. 100 m
• Thickness (A unit): 20 m or thicker
• Lower limit: Yagori Volcaniclastics, Odakegawa Lavas
• Lower limit: Unconformity (Kasuga Volcanic Rocks)

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

• Distribution: Yabashira creek - Otakegawa river, Yuzawa creek, Sakuho city, Minamisaku county, Nagano pref.; Hacchochigawa river, Saku city, Nagano pref.

• Nishiki and Takahashi (2012) Jour. Geol. Soc. Japan, vol.118, no.8, pp.499-515 DOI
• Nishiki et al. (2007) Jour. Geol. Soc. Japan, vol.113, no.5, pp.193-211 DOI
• Kawachi (1974) Geology of the Tateshinayama District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 114p. (in Japanese with English abstract 5p.)