[Abstract]

Yumuta tephra layers 1-9 (Yum 1-9) in ascending order are recognized in tephric loess between Aso-3 (110-123 ka) and K-Tz (90-95 ka) widespread tephras on the Yumuta plateau, west side of Yufudake volcano, Kyushu. Ata (95- 110 ka) widespread tephra is also seen between Yum2 and Yum3. Therefore, eruptive age of Yum3-9 is ca. 100 ka. Yum3, 7, 8 are correlated with Tsukahara 3, 2, 1 pumice layers (TP-3, TP-2, TP-1) at the north foot of Yufudake Volcano on the basis of shape of volcanic glass shards, the refractive indices of glass, orthopyroxene and hornblende. Mineral assemblage and refractive indices of minerals show that Yum8 is the tephra erupted from Kuju Volcano above Kuju-Shimosakata pyroclastic flow deposites and that Yum3 through 8 are correlated with a part of Aso-ABCD airfall pumice erupted from Aso Volcano.

e-mail:

furusawa@tephra.co.jp