10:45 〜 11:00
[SGC46-01] 放射起源・安定Sr同位体分析により明らかになった出土人骨の続成変質作用
キーワード：Sr同位体、考古科学、続成変質、アパタイト、火葬人骨
Hydroxyapatite, a main inorganic component in bones, contains Sr at high concentration up to the order of several hundreds of ppm. Radiogenic strontium isotope ratio (87Sr/86Sr) of bone hydroxyapatites has been used to study residential mobility of ancient humans and mammals in archeological fields. Strontium in human body is derived from the background geological system via foods such as plants and animals. Therefore, 87Sr/86Sr value of bone hydroxyapatite directly reflects 87Sr/86Sr value of the bedrocks in the region where the foods came from.
Archeological human remains have been buried in soils for hundreds of years or more. There is a strong possibility that the buried human bones have been affected by diagenetic process and the original 87Sr/86Sr values of the bone hydroxyapatites have been changed by such secondary alteration. Although evaluation of the effect of possible diagenetic alteration is essential in reconstructing the residential mobility of ancient humans from the bone hydroxyapatite 87Sr/86Sr data, reactivity of bone hydroxyapatite during diagenetic processes is not well understood.
In this study, we attempt to make a quantitative evaluation of secondary alteration effect on the bone hydroxyapatite 87Sr/86Sr during diagenesis. Hydroxyapatite fractions were extracted from a cremated human remain of a Buddhist priest Jokei (AD1155-1213) and three different cremated bodies excavated from Middle age sites in Binman-ji, Shiga, Japan. Bulk soil samples from the excavation sites as well as exchangeable phases of these soils were also prepared. Both the radiogenic (87Sr/86Sr) and stable (δ88Sr/86Sr) isotope ratios were analyzed for these samples. The results will be discussed in the presentation.
Archeological human remains have been buried in soils for hundreds of years or more. There is a strong possibility that the buried human bones have been affected by diagenetic process and the original 87Sr/86Sr values of the bone hydroxyapatites have been changed by such secondary alteration. Although evaluation of the effect of possible diagenetic alteration is essential in reconstructing the residential mobility of ancient humans from the bone hydroxyapatite 87Sr/86Sr data, reactivity of bone hydroxyapatite during diagenetic processes is not well understood.
In this study, we attempt to make a quantitative evaluation of secondary alteration effect on the bone hydroxyapatite 87Sr/86Sr during diagenesis. Hydroxyapatite fractions were extracted from a cremated human remain of a Buddhist priest Jokei (AD1155-1213) and three different cremated bodies excavated from Middle age sites in Binman-ji, Shiga, Japan. Bulk soil samples from the excavation sites as well as exchangeable phases of these soils were also prepared. Both the radiogenic (87Sr/86Sr) and stable (δ88Sr/86Sr) isotope ratios were analyzed for these samples. The results will be discussed in the presentation.