Researchers from the Archaeometry Laboratory of the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences, collaborating with the Zhejiang Provincial Institute of Cultural Relics and Archaeology, carried out a chronological analysis of pottery, burnt clay, and sediments unearthed in the Beicun archaeological site. This result was published in Quaternary Geochronology.
Beicun site, a Neolithic site of the early Liangzhu culture (about 3000-2000 BC), was excavated by the Zhejiang Provincial Institute of Cultural Relics and Archaeology from 2020 to 2021. Some important jade articles and lithics have been unearthed, including dragon head bracelets, jade huang, jade cicadas, and stone broad-axe, which provided the latest information for the research of the social development, class divisions, and the rise of Liangzhu Ancient city.
The locations of the Beicun archaeological site and experimental samples.
Thermoluminescence (TL) and optically stimulated luminescence (OSL) dating techniques have gained extensive archaeological application since their first use in pottery by Oxford University in the 1950s and 1960s. Single-aliquot regenerative-dose (SAR) and single-grain protocols have been employed to date potteries, porcelain, lithics (heated flint), burnt clay, kilns, bricks, slags, and other archaeological materials. However, systematic research on the OSL characteristics of heated ores has not been carried out yet.
The study first found and confirmed the relationship between the medium component signal of quartz and the material’s thermal history, especially the history being in the temperature ranging from 600 to 1000 °C. This signal is increased by high-temperature annealing but would not affect the result for age determination in general.
With a designed luminescence dating procedure and an R language statistical model, the researchers figured out the luminescence ages of pottery sherds and burnt clay, using OSL-SAR and TL-SAR protocols. The age obtained with luminescence methods corresponds to the 14C age of carbon bits extracted from the burnt clay.
Results showed that with standardized sampling and targeted test conditions, OSL and TL dating ensure accuracy. Moreover, it is expected to precisely determine the age of the last archaeological heating events, such as sacrifice, burning, or cooking.
The luminescence dating experiment is accomplished on the TL/OSL instruments, Risø DA-20 (Denmark).
(Written by TU Bingxin, edited by JIANG Pengcen, USTC News Center)