[HCG30-03] Radiocarbon dating of shell accumulations of the Late Shell Midden Period excavated at Okinawa.
Keywords:Shell Midden Period, radiocarbon age, shell accumulation
In the MEXT Grants-in-Aid for Scientific Research on Innovative Areas "Deciphering Origin and Establishment of Yaponesians mainly based on Genome Sequences" (Head Investigator: Saitou Naruya, National Institute of Genetics), the basic section "Elucidating the History of Yaponesian based on Archaeological Data" (Principal Investigator: Fujio Shin’ichiro, National Museum of Japanese History) is advancing the reexamination of the prehistoric age of Japan based on the high-precise numerical age by radiocarbon dating and dendrochronology, etc.. Interdisciplinary research with molecular anthropology in which genome research is rapidly advancing is performed, and the way of transfer and exchange of people who meet in the Yayoi period is being investigated.
What notices is the age of shell accumulation excavated in Okinawa. Shell accumulation is the remain of large snails such as Strombus latissimus and Conidae inhabiting coral reef, and it is often detected in the remains in the first stage of the Late Shell Midden period (from 5c BC to AD 5c) in Okinawa Islands. Yayoi earthenware from Kyushu is often found in the remains along with the local earthenware. Strombus latissimus collected in the remains include the roughly processed bracelets used by the Yayoi people of the same period in northern Kyushu. Therefore, the remains are considered to have been involved in the continuous shell trading between the Yayoi society and the shell mound society in Okinawa.
Since earthenware in this period has a bad residue of adhering carbides, the chronology by radiocarbon dating is not sufficient. On the other hand, the oceanic reservoir effect may affect the radiocarbon dating of seashells, and systematic measurement has not been performed until now. In this study, the authors received the offer of shells with the understanding of local boards of education and buried cultural property centers, etc., and carried out radiocarbon dating of 46 shells in the 2018 fiscal year.
The radiocarbon ages obtained seemed to be gathered in each shell accumulation. It is necessary to reflect the local reservoir effect (ΔR) in the calculation of calibration age, and the effect of old carbon derived from the coral reef is also should be taken into account. However, this time, the age was calibrated by Marine13 calibration curve, ignoring the effect (ΔR = 0), and the time was classified.
This research was supported by MEXT KAKENHI Grant Number JP18H05509.
What notices is the age of shell accumulation excavated in Okinawa. Shell accumulation is the remain of large snails such as Strombus latissimus and Conidae inhabiting coral reef, and it is often detected in the remains in the first stage of the Late Shell Midden period (from 5c BC to AD 5c) in Okinawa Islands. Yayoi earthenware from Kyushu is often found in the remains along with the local earthenware. Strombus latissimus collected in the remains include the roughly processed bracelets used by the Yayoi people of the same period in northern Kyushu. Therefore, the remains are considered to have been involved in the continuous shell trading between the Yayoi society and the shell mound society in Okinawa.
Since earthenware in this period has a bad residue of adhering carbides, the chronology by radiocarbon dating is not sufficient. On the other hand, the oceanic reservoir effect may affect the radiocarbon dating of seashells, and systematic measurement has not been performed until now. In this study, the authors received the offer of shells with the understanding of local boards of education and buried cultural property centers, etc., and carried out radiocarbon dating of 46 shells in the 2018 fiscal year.
The radiocarbon ages obtained seemed to be gathered in each shell accumulation. It is necessary to reflect the local reservoir effect (ΔR) in the calculation of calibration age, and the effect of old carbon derived from the coral reef is also should be taken into account. However, this time, the age was calibrated by Marine13 calibration curve, ignoring the effect (ΔR = 0), and the time was classified.
This research was supported by MEXT KAKENHI Grant Number JP18H05509.