[U-06] Evolution of New Seamless Science: From Space, Sun to the Earth Surface

[U06-P08] An attempt on 14C dating of carbonate hydroxyapatite in a cremated bone

*Hikari MUKUMOTO¹, Masayo MINAMI², Toshio NAKAMURA², Hiroyuki KAGI³ (1.Department of Earth & Planetary Sciences, Nagoya University, 2.Center for Chronological Research, Nagoya University, 3.Geochemical Research Center, Graduate School of Science, The University of Tokyo)

Keywords:bone, carbonate hydroxyapatite, radiocarbon dating

Bones are one of the most important materials for archaeological and paleo-environmental dating because they can directly provide absolute dates themselves. Bone collagen, which contains bone protein that is less susceptible to chemical weathering, is commonly used for ¹⁴C dating, but it sometimes has lost organic protein due to post-depositional chemical alternation and diagenesis, resulting in impossibility of ¹⁴C dating. For the bones remaining no organic component, carbonate hydroxyapatite, an inorganic component, is useful for ¹⁴C-measurement. However, the inorganic component in bones can easily be altered by acidic soil, and it has been considered to be unsuitable for ¹⁴C dating. Recently, meanwhile, it is reported that ¹⁴C dating using carbonate hydroxyapatite is possible for cremation bones heated at a high temperature (>600℃). The objective of this study is to examine the possibility of ¹⁴C dating using carbonate hydroxyapatite in cremated bones. The samples used were cremated bones in a funerary urn, which are considered to be remains of Jokei, a Buddhist monk (AD 1155-1213). The bones had been confirmed to be burned at high temperature, judged from the IR spectra and XRD patterns. The carbonate hydroxyapatite in six bone fragments showed ¹⁴C dates of 1155-1280 cal AD, which is similar with the supposed age. The result indicates that ¹⁴C dating using carbonate hydroxyapatite is effective when the bone sample was enough heated and well-preserved after deposition.