Hiraki Welded Tuff

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Hiraki Welded Tuff Yoshida and Kawata, 1987

Invalid synonym: Saikojiyama Formation

Type locality (Upper): Kiyomizuji temple, Hiraki, Kato city, Hyogo prefecture
Type locality (Lower): Kuroishi dam, Konda town, Nishiwaki city, Hyogo prefecture
Volcanic rocks
Late Cretaceous
Correlation (Lower): Moshi Welded Tuff, Sakaino Welded Tuff, Tanjosan Tuff Breccia
Intruded by: Shitodani Granite, Granite porphyry dyke, Diorite porphyry dyke, Diorite dyke

Sedimentary facies (Middle): Lacustrine
Lithofacies (Upper): Biotite rhyolite welded tuff
Lithofacies (Middle): Tuffaceous sandstone, Mudstone
Lithofacies (Lower): Biotite rhyolite welded tuff
Lithofacies (Lower, Minor): Tuff breccia

Thickness (Upper): 700 m or thicker
Thickness (Lower): ca. 600 m
Distribution (Length): ca. 21 km
Distribution (Width): ca. 9 km
Upper limit: Unconformity (Mita Formation)
Lower limit: Unconformity (Kamogawa Formation)

Arima Group (Tanba, Hyogo pref.)
[ Upper ]
~~~~~~~~~~~~~~
Hiraki Welded Tuff
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Kamogawa Formation / Akusa Formation
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[ Lower ]

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

Distribution: Hiraki - Akitsu, Kato city, Hyogo pref.; Konda town - Nakahata, Nishiwaki city, Hyogo pref.; Ishido, Kaibara town, Tamba city, Hyogo pref.; Kitaota - Kanaya, Sannaan town, Tamba city, Hyogo pref.; Ajima, Tannan tonw, Tambasasayama city, Hyogo pref.; Shitodani, Konda town, Tambasasayama city, Hyogo pref.; Okawase, Mita city, Hyogo pref.

Kurimoto et al. (1993) Geology of the Sasayama District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 93p. (in Japanese with English abstract 5p.)