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Tenmyozan Volcanic Rocks Yanagisawa et al., 1996

Some researchers suggest that Kaneyama Formation should be included in Natori Group.

Former Tenmyozan Formation was divided and the upper Ryozen Formation was separated.

Invalid synonym: Tenmyosan Agglomerate, Tenmyosan Formation

• Type locality: Kijio river, northeast of Mount Tenmyosan, Marumori city, Igu county, Miyagi prefecture
• Volcanic rocks
• Monogenetic volcanoes
• early Miocene
• Interfingered: Lower Member of Kaneyama Formation
• Correlation: Ryozen Formation
• Correlation (Lower): Lower Member of Kaneyama Formation, Shiote Formation

• Sedimentary facies: High-alkaline tholeiite
• Sedimentary facies (Top): Crater-fill
• Sedimentary facies: Pyroclastic cone
• Sedimentary facies (Minor): Vent-fill breccia
• Lithofacies (Top): Aa lava
• Lithofacies: Basalt, Andesite pyroclastic fall deposit, Pyroclastic surge deposit
• Lithofacies: Lapilli tuff, Volcanic breccia, Lapillistone
• Lithofacies (Minor): Sandstone, Mudstone
• Lithofacies (Basal): Sandstone, Conglomerate
• Sedimentary structures: Parallel stratification, Sandwave ripples

• Source: Mount Tateyama (Marumori city, Igu county, Miyagi pref.) and others
• Mode of eruption (Upper): Phreatomagmatic
• Mode of eruption (Lower): Magmatic
• Thickness: ca. 25 - 180 m
• Upper limit: Conformity (Upper Member of Kaneyama Formation), Unconformity (Ryozen Formation), Abut unconformity (Hazama Formation)
• Lower limit: Conformity/Interfingered (Shiote Formation), Abut unconformity (Granite)

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

• Distribution: Mount Tenmyosan - Sano - Kurosano - Minamidaira - Kaneyama - Shinmachi - Odate - Basen pass - Ouchi, Marumori city, Igu county, Miyagi pref.; Nakaizuka, Yamakami, Soma city, Fukushima pref.; Yubune, Iidate city, Soma county, Fukushima pref.; Katakura - Kitayashiki, Haramachi ward, Minamisoma city, Fukushima pref.

• Yanagisawa et al. (1996) Geology of the Somanakamura District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 114p. (in Japanese with English abstract 9p.)
• Kubo et al. (1990) Geology of the Haramachi and Omika District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 138p. (in Japanese with English abstract 7p.)
• Fujita et al. (1988) Geology of the Kakuda District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 99p. (in Japanese with English abstract 9p.)