Haruna-Futatsudake-Shibukawa Pyroclastic Flow Deposit

[ Top ] [ Japanese ]

Haruna-Futatsudake-Shibukawa Pyroclastic Flow Deposit Geshi and Takeuchi, 2012

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: Pyroclastic flow deposit (Multiple flow units)
Lithofacies: Orthopyroxene hornblende andesite
Lithofacies: Pumiceous lapilli, Volcanic sands, Volcanic breccia
Sedimentary structures: Reversed graded bedding

Source: Haruna volcano
Thickness: ca. 1 - 5 m or thicker
Thickness (A unit): 2 - 3 m
Volume: ca. 0.5 km³

Hr-FA Tephra
[ Upper ]
~~~~~~~~~~~~~~
Haruna-Futatsudake-Shibukawa Pyroclastic Flow Deposit
--------------
Haruna-Futatsudake-Shibukawa Fall Tephra
~~~~~~~~~~~~~~
[ Lower ]

Younger Haruna volcano
[ Upper ]
~~~~~~~~~~~~~~
Futatsudake Lava
~~~~~~~~~~~~~~
Hr-FP Tephra
~~~~~~~~~~~~~~
Hr-FA Tephra
~~~~~~~~~~~~~~
Younger Haruna Volcanic Fan Deposit
~~~~~~~~~~~~~~
Mizusawayama Lava / Mizusawayama Pyroclastic Flow Deposit and Talus Deposit
~~~~~~~~~~~~~~
Somayama Lava
~~~~~~~~~~~~~~
Jagatake Lava
~~~~~~~~~~~~~~
Harunafuji Lava
~~~~~~~~~~~~~~
Hr-HP Tephra
~~~~~~~~~~~~~~
[ Lower ]

Haruna volcano
[ Upper ]
~~~~~~~~~~~~~~
Younger Haruna volcano
~~~~~~~~~~~~~~
Older Haruna volcano
~~~~~~~~~~~~~~
[ Lower ]

------ 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.; Irisawa - Arima - Ubashima, Shibukawa city, Gunma pref.; Mizusawa, Ikaho town, Shibukawa city, 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.)