[ Top ] [ Japanese ]

Oa Unit Kawamura, 2010

• Type locality: Nakao, Ochi, Shimonoseki city, Yamaguchi prefecture
• Coherent formation
• Middle Jurassic, Bathonian - Callovian (Plants)
• Contemporaneous heterotopic facies: Ob Unit

• Sedimentary facies: Marine
• Sedimentary facies: Prodelta slope a the outer margin of a fan delta in a inner bay
• Sedimentary facies: Debris flow, Turbidite
• Lithofacies (Oa4-6): Mudstone-dominant interbedded sandstone and mudstone, Mudstone, Siltstone, Sandy mudstone
• Lithofacies (Oa4-6, Minor): Sandstone, Breccia
• Lithofacies (Oa3): Conglomerate, Sandstone
• Lithofacies (Oa3, Minor): Mudstone, Siltstone
• Lithofacies (Oa2): Mudstone-dominant interbedded sandstone and mudstone, Mudstone
• Lithofacies (Oa2, Minor): Sandstone
• Lithofacies (Oa1): Conglomerate
• Sedimentary structures (Oa4-6): Parallel stratification, Cross stratification, Graded bedding
• Sedimentary structures (Oa3): Planar cross-stratificationP
• Paleocurrent: Northwest

• Thickness (Oa1): 7 - 8 m
• 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 (Oa4-6): Phycosiphon isp., Plants
• Fossils (Oa3): Gleichenites? spp., Onychiopsis elongata
• Fossils (Oa2): Phycosiphon isp.

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