Sedimentary facies and radiocarbon ages of the alluvial-fan toes at the eastern foot of the Yoro Mountain

Hori, Kazuaki*; Nakanishi, Toshimichi; Hong, W.*; Nakashima, Rei*

Event sediments by debris flows were evaluated based on the sedimentary facies and radiocarbon ages of four sediment cores from the eastern foot of the alluvial fan toes at the eastern foot of the Yoro Mountains. In addition, the marine reservoir effect (MRE) in the Holocene was measured by the offset of radiocarbon ages between terrestrial plant fragments and marine shell fragments found in the same stratum in the core sediments. On the results, nine coarse sediment were observed after 4070 cal BP in three cores. The average of MRE, ca 400 years (n = 13) and ca 330 years (n = 12), were identified on two cores.