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Bonborigawa Unit (Sakai, 1987) Ueki et al., 2013

Invalid synonym: Bonborigawa Formation, Bomborigawa Unit, Bomborigawa Formation, Sasano Formation

• Type locality: Bonborigawa river, Akiruno city, Tokyo
• Accretionary complex
• Deposition: Late Cretaceous, Santonian - Campanian

• Sedimentary facies: Marine
• Lithofacies: Coherent facies
• Lithofacies (Minor): Broken facies
• Lithofacies: Sandstone, Interbedded sandstone and mudstone
• Lithofacies (Minor): Conglomerate, Phyllitic shale, Tuff
• Sedimentary structures: Groove cast, Imbrication
• Paleocurrent: North to South, West to East

• Thickness: ca. 1,500 m or thicker
• Upper: Unconformity (Ongata Formation)

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

• Distribution: Bonborigawa river, Akiruno city, Tokyo; Wada pass, Tokyo - Kanagawa pref.; Kazuma, Hinohara city, Nishitama county, Tokyo; Tama river - Onagasakuzawa creek, Kosuge city, Kitatsuru county, Yamanashi pref.; Yamairigawa river - Daigo river - Otsu town, Hachioji city, Tokyo; Takizawa river, Ongata, Hachioji city, Tokyo
• Fossils (Radiolarians): Alievium gallowayi, Amphipyndax cf. enesseffi, Amphipyndax stocki, Archaeodictyomitra cf. simplex, Archaeodictyomitra cf. sliteri, Archaeospongoprunum nishiyamae, Cryptamphorella sp., Dictyomitra duodesimcostata, Dictyomitra koslovae, Kuppelella sp., Orbiculiformia sp., Patellula sp., Protoxiphotractrus spp., Pseudoaulophacus lenticulatus, Stichomitra asymbatos, Tanarla sp., Theocampe tina, Theocampe urna, Zifondium spp.

• Ueki et al. (2013) Geology of the Hachioji District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 137p. (in Japanese with English abstract 6p.)
• Ueki and Sakai (2007) Geology of the Ome District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 189p. (in Japanese with English abstract 5p.)
• Sakai (1987) Geology of the Itsukaichi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 75p. (in Japanese with English abstract 5p.)