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Hikoma Formation Ito et al., 2022

• Type locality: Terasawa creek - Takarakurasawa creek, Hikoma town, Sano city, Tochigi prefecture
• Volcanic rocks
• Caldera-fill deposit
• middle Miocene (12.3 Ma, FT)

• Sedimentary facies (Top): Terrestrial
• Sedimentary facies: Lacustrine, Talus deposit
• Lithofacies (Top): Rhyolite lava
• Lithofacies: Breccia, Interbedded tuffaceous sandstone and tuffaceous mudstone

• Thickness: ca. 100 m
• Lower limit: Abut unconformity (Kurohone-Kiryu Complex)

• Distribution: Terasawa creek - Takarakurasawa creek, Hikoma town, Sano city, Tochigi 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.)