[ Top ] [ Japanese ]

Higashidai Formation Umino et al., 2016

• Type locality: Higashidai, Hahajima, Ogasawara city, Tokyo
• Volcanic rocks
• middle Eocene (45 - 43 Ma)
• Upper: Eocene (44.0 - 42.7 Ma, Ar-Ar)
• Lower: Eocene (45.3 Ma, Ar-Ar)

• Sedimentary facies (Upper): Terrestrial
• Sedimentary facies (Lower): Submarine eruption and subaqueous deposit
• Lithofacies: Calc-alkaline series
• Lithofacies (Upper): Andesite - Basalt water-chilled volcanic bomb, Scoria, Andesite hyaloclastite
• Lithofacies (Lower): Welded water-chilled volcanic bomb, Scoria, Andesite hyaloclastite
• Lithofacies (Minor): Volcanic ash, Volcanic conglomerate, Tuff breccia, Vent lava

• Thickness: 1,300 m or thicker
• Upper limit: Unconformity (Sekimon Formation, Nishiura Formation)

• Distribution: Higashidai - Nishidai - Nagahama - Kanzaki, Hahajima, Ogasawara city, Tokyo

• 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.)