Late Quaternary Tephras in the Southern Part of the tokachi Plain, Hokkaido

摘要

Kutcharo-Haboro tephra (Kc-Hb), Sinsei tephra (Sns: in this paper), and Azuma-4 tephra (Aafa4) are intercalated in the lower part of the fluvial-peaty sediments which were deposited succeeding the Last Interglacial (Oxygen Isotope Stage 5e) in the southern part of the Tokachi Plain. These three tephras are identified on the basis of petrographic pro- perties such as mineral compositions and re- fractive indices of volcanic glass, orthopy- roxene, and hornblende.