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Nishiura Formation Umino et al., 2016

• Type locality: Nishiura, Hahajima, Ogasawara city, Tokyo
• Volcanic rocks
• Eocene (ca. 43 - 41 Ma)
• Intruded by: Dykes

• Lithofacies: Calc-alkaline series
• Lithofacies (Top): Sandstone, Conglomerate
• Lithofacies: Andesite hyaloclastite, Conglomerate
• Lithofacies (Minor): Basalt hyaloclastite
• Lithofacies (Lower, Minor): Lithic pyroclastic flow deposit, Aa lava
• Lithofacies (Bottom): Conglomerate

• Thickness: 370 m or thicker
• Upper limit: Unconformity (Sekimon Formation)
• Lower limit: Unconformity (Higashidai Formation)

• Distribution: Nishiura - Higashizaki bay - Okuzure bay - Inokuma bay, Hahajima, Ogasawara city, Tokyo
• Fossils (Forminifera): Asterocyclina incisuricamerata, Asterocyclina pentagonalis, Asterocyclina stella, Daviesina boninensis, Discocyclina augustae, Discocyclina dispansa, Nummulites aturicus, Nummulites gizehensis, Nummulites millecaput, Nummulites pengaronensis, Nummulites perforatus, Operculina schwageri, Orbitoclypeus kimurai

• Umino et al. (2016) Geology of the Hahajima Retto District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 46p. (in Japanese with English abstract 2p.)