Formation age of the fluvial terraces along the Kaburakawa River, Kanto, Japan

Tajikara, Masayoshi; Takada, Keita*; Furusawa, Akira*; Morita, Yoshimune*; Sugai, Toshihiko*

We investigated fluvial terraces along the Kaburakawa River, in order to clarify the model of fluvial terrace development. Based on air photo analysis, fluvial terraces in the study area were classified into four categories (Q1-Q4). Existing papers reported that Q3 was formed in Marin Oxygen Isotope Stage (MIS) 2. In this study, we found a fragment of tree which is identified as or . This fact indicates that Q3 was formed in relatively cold age. Q2 is distributed at higher level than Q3. We found Iizuna-Kamitaru Tephra (Iz-Kt) at the lowermost part of aeolian deposits or uppermost part of overbank deposits in some outcrops of Q2 deposits. Since Iz-Kt is believed to fall at boundary of MIS 5 and 6, we concluded that Q2 deposits was accumulated in MIS 6 and that Q2 was incised in MIS 5.