Radiocarbon dating of charred human bone remains preserved in urns excavated from medieval Buddhist cemetery in Japan

摘要

For a preliminary test of ~(14)C dating of cremated human remains, we have collected charred bone and wood-charcoal fragments from cremated remains contained in cinerary urns that had been excavated from medieval Buddhist cemetery at the Hoenji temple in Aichi prefecture, central Japan. More than 230 urn vessels were discovered from the excavated area of ca. 14 m wide and 14 m long. The identification of charred bone or charcoal fragments among the remains was performed by observation of surface appearance, inspection of fine structures by a microscope, bubble formation during the HC1 treatments in preparing target material for AMS ~(14)C dating, carbon and nitrogen contents, δ~(13)C and δ~(15)N values of the fragments. All ~(14)C ages obtained for the samples that were identified as charred bone remains were almost consistent with the archeological age estimated based on typological analysis of respective urns. On the other hand, some ~(14)C ages for the remains identified as wood charcoal, which had been produced from firewood or a wooden coffin during the cremation, were not consistent with archeological estimation, shifting toward older ~(14)C ages, most probably as the result of old wood effect.