Gyodosan Complex

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Gyodosan Complex Ito, 2021

Type locality: Mount Gyodosan, Ashikaga city, Tochigi prefecture
Accretionary complex
Deposition (Chert): Permian, Triassic, Jurassic (Radiolarians)
Deposition (Mudstone): Middle Jurassic, Bajocian - early Bathonian (Radiolarians)
Accretion: Middle Jurassic

Sedimentary facies: Marine
Lithofacies: Mélange facies
Lithofacies: Chert
Exotic blocks (Crusts): Siliceous mudstone, Mudstone, Sandstone
Lithofacies (Upper): Mélange dominant
Lithofacies (Lower): Chert dominant

Thickness: 1 km
Upper limit: Unconformity (Kanayama Welded Tuff, Hirosawa Conglomerate, Yabuzuka Formation)
Lower limit: Oiwa Fault

Ashio Belt (Ashio Mountains)
[ Upper ]
/--/--/--/--/-
Gyodosan Complex
/--/--/--/--/-
Kuzu Complex, Unit 3
/--/--/--/--/-
Kuzu Complex, Unit 2
/--/--/--/--/-
Omama Complex
/--/--/--/--/-
Kuzu Complex, Unit 1
/--/--/--/--/-
Kurohone-Kiryu Complex
/--/--/--/--/-
[ Lower ]

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

Distribution: Mount Gyodosan, Ashikaga city, Tochigi pref.; Yoshizawa town, Ota city, Gunma pref.; Hirosawa town, Kiryu city, Gunma pref.

Ito et al. (2022) Geology of the Kiryu and Ashikaga District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 101p. (in Japanese with English abstract 4p.)