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Sanbagawa Metamorphic Rocks

Synonym: Sanbagawa Belt, Sanbagawa Metamorphic Complex

Aoki 2019 divided to three units: Oboke Unit, Asemigawa Unit, Besshi Unit by the ages of protolith.

• Type locality: Sanbagawa, Onishi, Fujioka city, Gunma prefecture
• High P/T metamorphic rocks (Chlorite zone): 0.4 - 0.6 GPa, 240 - 300 degree C
• High P/T metamorphic rocks (Oligoclase-Biotite zone): 0.9 - 1.1 GPa, 585 - 635 degree C
• Protolith: Shimanto Belt
• Deposition: Early - Late Cretaceous (140 - 80 Ma, U-Pb; 100 Ma or later, FT)
• Accretion: Early Cretaceous - Paleogene (120 - 60 Ma, U-Pb)
• Metamorphism (Peak, Oligoclase-Biotite zone): Late Cretaceous (85.6 Ma, U-Pb)
• Metamorphism (Greenschist facies, Retrogressive): Late Cretaceous - Paleocene (82.0 - 58.0 Ma, K-Ar)
• Correlation: Yoshimi Metamorphic Rocks?
• Intruded by: Kifune Granodiorite

• Sedimentary facies: Trench-fill deposits, Hemi-pelagic sediments
• Metamorphic facies: Pumpellyite-Actinolite, Glaucophane, Epidote-Amphibolite, Eclogite
• Lithofacies (Protolith): Mudstone, Basalt volcanic sands, Reworked hyaloclastite, Lava, Dolerite, Chert
• Lithofacies: Pelitic schist, Green schist, Siliceous schist
• Lithofacies (Minor): Psammitic schist, Calcareous schist, Serpentinite

• Thickness: ca. 2,000 m
• Distribution (Length): ca. 800 km
• Distribution (Width): ca. 1 - 3 km
• Upper limit: Todai Tectonic Line (Nagano), Aridagawa Tectonic Line (Wakayama) (Chichibu Belt)

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

• Distribution: Gunma - Saitama - Nagano - Tokai region - Kii peninsula - Shikoku - Saganoseki peninsula, Kyushu
• Distribution (Chlorite zone): Kiraidani river - Kitadani river - Jintsudani river, Kamiyama city, Myozai county, Tokushima pref.; Mima city, Tokushima pref.

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