[ Top ] [ Japanese ]

Hachiryuzan Formation (Matsumoto and Kanmera, 1952) Tanaka et al., 1998

• Type locality: Mount Hachiryu, Sakamoto village, Yatsushiro city, Kumamoto prefecture
• Coherent formation
• Deposition: Early Cretaceous, early - middle Barremian

• Sedimentary facies: Marine
• Depth of water: Shallow
• Lithofacies (Main): Mudstone, Siltstone with calcareous nodules
• Lithofacies (Bottom): Well-sorted conglomerate including chert, Interbedded sandstone and mudstone

• Thickness: 80 - 350 m
• Upper limit: Conformity (Kesado Formation), Disconformity (Imaizumigawa Formation)
• Lower limit: Conformity (Kawaguchi Formation)

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

• Distribution: Sakamoto village, Yatsushiro city, Kumamoto pref. - Zare, Toyo village, Yatsushiro city, Kumamoto pref.
• Fossils: Crinoids, Ammonoids (Pulchellia (Heinzia) sp. cf. H. Provincialis)
• Fossils (Bivalves): Nipponitorigonia plicata, Cosmetodon sp., Nemodon sp., Glycymeris sp., Gervillaria sp., Entolium sp., Neithea (Neithea) atava, Neithea (Neithea) sp. aff. N. (N.) amanoi, Neithea matsumotoi, Chlamys shikokuensis, Aequipecten sp., Limatula sp., Rutitrigonia sanchensis, Pterotrigonia hokkaidoana, Pterotrigonia yokoyamai, Xenocardita amanoi, Ptycomya sp. aff. densicostata, Globocardium sphaeroideum

• Miyake et al. (2015) Jour. Geol. Soc. Japan, vol.121, no.12, pp.447-462, DOI