Ichiibara Formation

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Ichiibara Formation

Type locality: Ichiibara, Kawamoto city, Ochi county, Shimane prefecture
Volcanic rocks
Late Cretaceous (92 Ma, FT)
Intruded by: Onbara Granite, Kawamoto Granodiorite

Lithofacies: Rhyolite welded tuff

Thickness: 1,100 m or thicker

Distribution (Northeast - Southwest): ca. 7 km

Distribution (Northwest - Southeast): ca. 3 km

Upper limit: Conformity (Yadani Formation), Unconformity (Sakurae Group)

Ochi Group
[ Upper ]
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Yadani Formation
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Ichiibara Formation
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[ Lower ]

Mochigase stage volcanic rocks
?--?--?--?--?-
Hikimi Group
?--?--?--?--?-
Abu Group
?--?--?--?--?-
Ochi Group
?--?--?--?--?-
Yakumo Volcanic Rocks
?--?--?--?--?-

Sanin Belt
[ Young ]
~~~~~~~~~~~~~~
Tamagawa stage volcanic rocks
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Younger Inbi stage intrusive rocks
?--?--?--?--?-
Older Inbi stage intrusiv rocks
?--?--?--?--?-
Inbi stage volcanic rocks
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Mochigase stage intrusive rocks
?--?--?--?--?-
Mochigase stage volcanic rocks
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[ Old ]

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

Distribution: Ichiibara - Hanbe - Kirobara - Mount Takahoriyama - Mount Ichinomaru - Inugaya, Kawamoto city, Ochi county, Shimane Shimane pref.; Shirinashigawa river - Somori - Takahata - Hongo - Hamahara dam - Motoyama - Mukatani, Misato city, Ochi county,

Kano et al. (2001) Geology of the Yunotsu and Gotsu District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 129p. (in Japanese with English abstract 5p.)
Matsuura (1990) Geology of the Akana District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 73p. (in Japanese with English abstract 5p.)
Hattori et al. (1983) Geology of the Sambesan District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 168p. (in Japanese with English abstract 7p.)