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Hr-FA Tephra

Abbr.: Hr-FA

Invalid synonym: Hr-S

• Type locality: Kurosawa river, Ono, Shibukawa city, Gunma prefecture
• Type locality: Takizawa river, Uenohara, Yoshioka city, Kitagunma county, Gunma prefecture
• Tephra
• Holocene (end of 5th century; 489 cal AD, Wiggle matching)

• Sedimentary facies (Upper): Pyroclastic surge
• Sedimentary facies (Middle): Pyroclastic flow deposit
• Sedimentary facies (Lower): Pyroclastic fall deposit
• Lithofacies: Orthopyroxene hornblende andesite
• Lithofacies (Upper): Lapilli, Volcanic sands
• Sedimentary structures (Upper): Parallel stratification

• Source: Haruna volcano
• Mode of eruption: Phreatomagmatic
• Thickness (Upper): ca. 20 - 40 cm
• Lower limit: Unconformity (Somayama Lava)

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

• Distribution: Kurosawa river, Ono, Shibukawa city, Gunma pref.; Takizawa river, Uenohara, Yoshioka city, Kitagunma county, Gunma pref.

• Geshi and Takeuchi (2012) Geology of the Haruna San District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 79p. (in Japanese with English abstract 3p.)