[ Top ] [ Japanese ]

Asahiyama Formation Umino, 1985

• Type locality: Mount Asahiyama, Chichijima, Ogasawara city, Tokyo
• Volcanic rocks
• Eocene

• Lithofacies: Quartz-bearing dacite - Rhyolite lava, Tuff breccia, Hyaloclastite
• Lithofacies (Lower): Interbedded sandstone and conglomerate, Tuff breccia

• Thickness: 200 m or thicker
• Upper limit: Abut unconformity (Mikazukiyama Formation)
• Lower limit: Unconformity (Maruberiwan Formation)

• Distribution: Mount Asahiyama - Sakaiura - Kiyose - Tennoura - Tatsumizaki - Mount Tsuitateyama - Mount Akahatayama - Nakayama pass - Mount Tsutsujiyama, Chichijima, Ogasawara city, Tokyo; Mount Togariyama - Cape Futamata, Anijima, Ogasawara city, Tokyo

• Umino and Nakano (2007) Geology of the Chichijima Retto District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 71p. (in Japanese with English abstract 3p.)