Ash-flow tuffs of the Chisulryoung volcanic formation and associated welded tuff instrusion, Weolseong district, Southern Korea

鵄述嶺 地域에 分布하는 火山岩은 Ash flow tuff, intrusive welded tuff 및 Diatreme으로 細分된다. 第三紀 初期에 噴出한 Ash flow tuff는 6個의 層(Member)으로 區分되고, 各層(Member)의 岩相 變化는 岩柱型의 Intrusive welded tuff가 火山 噴出 火口였음을 暗示한다.

The Chisulryoung Volcanic Formation comprises a thick sequence of pyroclastic flow deposits. Six members are distinguished, each representing separate flow units, comprising weakly to intensely welded acidic tuffs. A stock of welded acidic tuff, 1 km in diameter, intrudes hornblende granodiorite and sediments of Late Cretaceous age and the lower part of the Chisulryoung Volcanic Tuff Formation and may represent the vent through which the upper flows of the Chisulryoug Volcanic Formation were erupted.