Radiocarbon in 9th to 5th Century BC Tree-Ring Samples from the Ouban 1 Archaeological Site, Hiroshima, Japan

In order to investigate the regional atmospheric radiocarbon offset, accelerator mass spectrometry (AMS) 14 C measurements were made on 5-yr increments of a Japanese wood sample dendrochronologically dated to 820–436 BC. The 14 C data from the Japanese tree-ring samples were compared with the IntCal04 calibration curve (Reimer et al. 2004). In most parts, the differences between IntCal04 and 14 C dates in the Japanese tree-ring samples were within experimental statistical errors. At around 680 BC, however, significant differences of up to 100 14 C yr were observed. These differences may indicate either regional offsets in Japan or the short-term fluctuation of a subdecadal timescale in atmospheric 14 C variations.