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Ob Unit Kawamura, 2010

• Type locality: southeast of Takaji pass, Shimonoseki city, Yamaguchi prefecture
• Coherent formation
• Middle Jurassic, Bathonian - Callovian (Plants)
• Contemporaneous heterotopic facies: Oa Unit

• Sedimentary facies: Marine
• Sedimentary facies: Lower slope of fan delta in a inner bay
• Sedimentary facies: Turbidite
• Depth of water: Shallow (shallower than fair-weather wave base)
• Lithofacies: Sandstone
• Lithofacies (Ob7): Mudstone-dominant interbedded sandstone and mudstone, Siltstone
• Lithofacies (Ob7, Minor): Sandstone, Gravelly sandstone, Conglomerate
• Lithofacies (Ob2-6): Sandstone-dominant interbedded sandstone and mudstone, Sandstone
• Lithofacies (Ob2-6, Minor): Interbedded sandstone and mudstone
• Lithofacies (Ob1): Mudstone-dominant interbedded sandstone and mudstone, Siltstone
• Lithofacies (Ob1, Minor): Sandy mudstone, Sandstone
• Sedimentary structures (Ob2-6): Erosional channels, Wave-formed ripples, Flame structures

• Thickness (Ob7): 55 m or thicker
• Thickness (Ob2-6): 66.2 m
• Thickness (Ob1): 40.3 m or thicker
• Upper limit: bottom of acidic tuff bed or sandstone bed of Oc Unit

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

• Distribution: Nakao - Oka, Ochi, Shimonoseki city, Yamaguchi pref.; Kamitabe, Shimonoseki city, Yamaguchi pref.
• Fossils (Ob7): Plants
• Fossils (Ob1): Plants

• Kawamura (2010) Jour. Geol. Soc. Japan, vol.116, no.1, pp.27-44 DOI