Single-year radiocarbon dating of Japanese tree rings of the 9-10th century including the 946CE eruption of the Baitoushan Volcano.
Dr. Minoru Sakamoto1,2, Dr. Takumi Mitsutani3, Dr. Fuyuki Tokanai4
1National Museum of Japanese History, Sakura, Japan, 2The Graduate University for Advanced Studies, Sakura, Japan, 3Nara National Research Institute for Cultural Properties, Nara, Japan, 4Yamagata University, Kaminoyama, Japan
After the discovery of the rapid increase in atmospheric ¹⁴C concentration at 775CE, known as the Miyake event, radiocarbon dating of tree rings is intensively promoted to certify the event and to find similar behaviors. As a result, a large amount of single-year radiocarbon ages of the 8th-century corresponding to the 775CE event and of around 1000CE corresponding to the subsequent 993CE event were accumulated. The IntCal20 calibration curve contains these data, however, single-year radiocarbon data of the 10th century still seems to be inadequate. Therefore we conducted single-year radiocarbon dating of Japanese tree rings of the 9-10th century to confirm the fine structure of ¹⁴C concentration.
The wood of Japanese cypress (Chamaecyparis obtusa) was provided by Iida City, Nagano, Japan. Dendrochronological age determination resulted in the range of 795-1055CE (t=9.2) matching with the master chronology for central Japan. Plate-like bleaching of the butt end of the tree rings was carried out to obtain cellulose of single-year. Graphitization and AMS radiocarbon measurement was performed by YU-AMS.
The radiocarbon ages of the single-year cellulose were mainly located above the IntCal20 calibration curve. The period includes the 946CE eruption of the Baitoushan (Changbaishan) volcano located on the border between China and North Korea, as determined by ¹⁴C spike matching based on the Miyake event. Previous attempts of ¹⁴C wiggle matching for this eruption had not been very successful, suggesting instability in the calibration curve. Additional accumulation of the radiocarbon ages of tree rings of this period is also needed.
Profile: Investigating historic materials with scientific approaches, especially dating.
Education: The Graduate University of the University of Tokyo — Ph. D., 2003.
Skills: Chemistry, stable isotope analysis, AMS radiocarbon dating.