b Member

[ Top ] [ Japanese ]

b Member

Synonym: U-IIb

Coherent formation
Late Cretaceous, early - middle Campanian (Bivalves)

Sedimentary facies: Marine
Sedimentary facies: Outer shelf
Lithofacies: Mudstone, Sandstone, Sandy mudstone
Sedimentary structures: Cross-stratification, Parallel stratification

Thickness: 250 m or thicker
Upper limit: Conformity
Lower limit: Conformity

b Member
[ Upper ]
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b3 Member
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b2 Member
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b1 Member
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[ Lower ]

U-II Formation
[ Upper ]
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b Member
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a Member
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[ Lower ]

Himenoura Group (Koshikijima islands)
[ Upper ]
~~~~~~~~~~~~~~
U-IV Formation
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U-III Formation
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U-II Formation
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U-I Formation
?--?--?--?--?-
[ Lower ]

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

Distribution: Tsuburazaki seashore, Shimokoshikijima island, Koshikijima islands, Satsumasendai city, Kagoshima pref.
Fossils: Nautilus, Echinoids, Sharks (Teeth), Bryozoa, Corals
Fossils (Ammonoids): Glyptoxoceras sp., Texanites sp., Eupachydiscus haradai
Fossils (Bivalves): Sphenoceramus schmidti, Inoceramus toyajoanus (Inoceramus balticus subsp. toyajoanus), Inoceramus ezoensis, Loxo japonica, Glycymeris amakusensis, Apiotrigonia crassoradiata, Apiotrigonia amanoi, Nanonavis. sachalinensis, Ezonuculana mactraeformis, Malletia himenourensis, Nippononectes tamurai, Protocardia koshikijimensis, Fenestricardita densigranulata, Peripromya nagaoi, Eriphyla sp.
Fossils (Radiolarians): Amphipyndax pseudoconulus, Dictyomitra koslovae, Dictyomitra formosa

Komatsu et al. (2014) Jour. Geol. Soc. Japan, vol.120, Supplement, pp.19-39 DOI
Tonai et al. (2008) Jour. Geol. Soc. Japan, vol.114, no.11, pp.547-559 DOI