大分県稲積水中鍾乳洞と阿蘇巨大噴火

A submerged calcite speleothem sample from Inazumi Cave, Oita, was dated by TIMS. The speleothem became submerged by accumulation of the Aso welded-tuff. The age of the analysed portion of the sample was 170,000 years B.P., suggesting that it was deposited before the earlier Aso-2 and & -3 eruptions and has been drowned in the groundwater at least three times. Many speleothems are submerged for a period longer than over 85,000 years, and …