[ Top ] [ Japanese ]

Izuhara Unit (Ishida, 1998) Hara et al., 2014

Invalid synonym: Izuhara Formation, Furuya Formation, Nishikawa Formation, Hayama Formation

• Type locality: Izuhara, Naka city, Naka county, Tokushima prefecture
• Accretionary complex
• Deposition (Chert): Late Triassic - Early Jurassic (Radiolarians, Conodonts)
• Deposition (Limestone): Late Jurassic, Oxfordian - Tithonian (Radiolarians)
• Deposition (Mudstone): Early Cretaceous, Aptian - Albian (Radiolarians)
• Early Cretaceous, Aptian - Albian
• Correlation (Limestone): Torinosu Group

• Sedimentary facies: Marine
• Lithofacies: Mélange facies, Broken facies
• Matrix: Sandstone, Interbedded sandstone and mudstone
• Exotic blocks (Crusts): Chert, Limestone (Micrite, Biomicrite), Mudstone
• Sedimentary structures: Graded bedding, Convolute stratification

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

• Distribution: Izuhara - Nishiu - Hirano - Tochitaniguchi - Ishidatami - Oriu - Kitagawa - Naro - Hodono, Naka city, Naka county, Tokushima, Tokushima pref.
• Fossils: Conodonts
• Fossils (Shellfishes): Astarte cf. semicostata, Glauconia neumayri, Natica (Amaruropsis) sanchuensis
• Fossils (Radiolarians): Archaeodictyomitra vulgaris, Holocryptocanium japonicum, Thanarla conica, Thanarla elegantissima, Thanarla praeveneta
• Fossils (Limestone): Corals (Aplosmilia? sp.), Echinoids, Sponges (Spongiomorpha cf. globosa), Foraminifera, Stromatoporoids (Milleporidium fasciculatum, Parastromatopora sp.), Radiolarians

• Hara et al. (2014) Geology of the Kitagawa District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 72p. (in Japanese with English abstract 4p.)
• Kiminami and Toda (2007) Jour. Geol. Soc. Japan, vol.113, no.4, pp.158-167 DOI