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Happyakudani Unit (Watabe et al., 1958) Hara et al., 2010

Invalid synonym: Happyakudani Formation, Mameyakizawa Formation, Idosawa Formation, Sogoya Formation, Aoiwatani Formation, Kosode Formation

• Accretionary complex
• Submarine landslide deposit of Chichibu Belt
• Deposition (Chert): Permian - Triassic; Middle - Late Jurassic
• Deposition (Limestone): Late Jurassic - Early Cretaceous
• Deposition (Shale): Late Cretaceous, Coniacian - Campanian (Radiolarians)
• Accretion: Late Cretaceous, Coniacian - Campanian
• Correlation (Limestone): Torinosu Group

• Sedimentary facies: Marine
• Lithofacies: Shale, Mélange facies
• Lithofacies (Minor): Sandstone, Siliceous shale, Tuffaceous shale, Chert, Limestone, Basalt
• Sedimentary structures: Graded bedding

• Thickness: ca. 1,700 m
• Upper limit: Thrust fault (Kumotoriyama Unit)
• Lower limit: Thrust fault (Koreisan Unit)

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

• Distribution: Aoiwadani valley - Minetani river, Okutama city, Nishitama county, Tokyo; Happyakudani valley - Kanayamazawa creek - Mameyakizawa creek - Shinnosawa - Okamidaira, Otaki, Chichibu city, Saitama pref.; Aoiwadani valley, Tabayama city, Kitatsuru county, Yamanashi pref.
• Fossils (Radiolarians): Acaeniotyle cf. umbilicata, Alievium spp., Amphipyndax stocki, Archaeodictyomitra lacrimula, Archaeodictyomitra simplex, Archaeodictyomitra sliteri, Archaeodictyomitra vulgaris, Archaeospongoprunum bipartitum, Archaeospongoprunum imlayi, Artostrobium cf. tina, Artostrobium cf. urna, Cornutella cf. californica, Diacanthocapsa sp., Dictyomitra cf. andersoni, Dictyomitra formosa, Dictyomitra koslovae, Emiluvia orea, Eucyrtidiellum cf. ptyctum, Eucyrtis tenuis, Hemicryptocapsa cf. polyhedra, Holocryptocanium barbui, Hsuum spp., Pantanellium spp., Pantellula planoconvexa, Parvicingula dhimenaensis, Praeconocaryomma universa, Protunuma cf. japonicus, Pseudoaulophacus lenticulatus, Pseudoaulophacus cf. praefloresensis, Pseudodictyomitra cf. carpatica, Pseudodictyomitra pentacoleensis, Pseudodictyomitra pseudomacrocephale, Pseudodictyomitra cf. vestalensis, Pyramispongia glascockensis, Rhopalosyringium cf. majuroensis, Sethocapsa sp., Stichocapsa sp., Stylocapsa cf. oblongula, Syringocapsa sp., Thanarla conica, Thanarla cf. praeveneta, Tricolocapsa spp., Unuma cf. typicus, Vitorfus cf. brustolensis, Xitus cf. plenus
• Fossils (Aoiwatani Formation, Radiolarians): Afens liriodes, Alievium gallowayi, Amphipyndax alamedaensis, Amphipyndax cf. plousios, Archacodictyomitra sp., Carpocanapsis costatum, Cryptamphorella macropora, Cryptamphorella sphaerica, Diacanthocapsa umbilicata, Dictyomitra formosa, Dictyomitra kaslovae, Mirifusus baileyi, Pantanellium cf. fisheri, Paronaella sp., Parvicingula sp., Patulibrackium sp., Pseudoaulophacus florensis, Pseudoaulophacus lenticulalus, Pseudodictyomitra sp., Stichomitra sp.
• Fossils (Chert, Conodonts): Anchignathodus sp., Crypridodella mediocris, Epigondolella cf. primittia, Neogondolella bulgarica, Neogondolella excelsa, Neogondolella polygnathiformis, Neohindeodella multihamata, Neospathodus dieneri
• Fossils (Torinosu-type limestone): Stromatolite, Bryozoans, Foraminifera, Brachiopods, Crinoids, Calcareous algae (Pycnoporidium lobatum)
• Fossils (Torinosu-type limestone, Stromatoporoids): Stromatopora japonica, Tosastroma tokunagai
• Fossils (Torinosu-type limestone, Corals): Actinastrea? sp., Calamophyllia sp., Chaetetoposis crinita, Dimorphoseries tabayamensis, Enallhelia sp., Isastrea? sp., Spongiomorpha asiatica, Stylina kantoensis, Thamnasteria huzimotoi, Trocharea sp.

• Hara et al. (2010) Geology of the Mitsumine District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 110p. (in Japanese with English abstract 4p.)
• Sakai (1987) Geology of the Itsukaichi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 75p. (in Japanese with English abstract 5p.)