Zhang, Xiaoyu and Huang, Dasong and Han Deng, Han and Snape, Colin and Meredith, Will and Zhao, Ye and Du, Yong and Chen, Xin and Sun, Yongge
Determining the lower limit of Liangzhu culture based on black carbon purification with hydropyrolysis technique.
Quaternary Geochronology, 30
Located in the middle and lower reaches of the Yangtze River, the Liangzhu Culture was one of the most important Neolithic cultures at the dawn of Chinese civilization. However, uncertainty over the lower age limit ending the Liangzhu Culture has resulted in a lack of consensus in defining its timespan. In order to establish the lower age limit, a representative site of late Liangzhu Culture, the Bianjiashan wharf, located in Hangzhou City, Zhejiang Province, Eastern China, was selected for investigation. Wooden stakes in the wharf and charcoals in the sediment profile near to the wharf site were collected for 14C AMS dating. To remove any contaminants, the charcoals were pre-treated by catalytic hydropyrolysis (HyPy) to isolate black carbon fractions (BCHyPy).
The continuous charcoal age distribution along the vertical profile of the silt core suggests the continual occupation of the Bianjiashan Site and that the site was developed soon after the river formed. The end of river sedimentation indicates that the demise of the Bianjiashan Site occurred no later than Cal BC 2470 (95% probability). The mean age of the more recent calendar calibrated age range BC 2525 for the BCHyPy residue is consistent with earlier evidence. The wharf, as a typical structure of the late Liangzhu Culture, was established between Cal BC 2635 and 2890 (95% probability). The start of the river charcoal sedimentation was found to have a very similar overall age span and, therefore, the river existed at the Bianjiasha Site for no more than a maximum of just over 400 years, which is taken as the maximum period, it was occupied by the Liangzhu population. In comparison to the fresh charcoal samples, the BCHyPy fractions and products were generally found to have similar probability age distributions. GC-MS analysis of the products (non-BCHyPy fractions) released by HyPy indicated that . Tthe exogenous carbon from plants in the charcoal is present as both covalently bonded and adsorbed species, and was deposited at the same time as the charcoal, suggesting that the sediments have been preserved in a closed environment without disturbance as soon as the river ceased to exist. Thus, HyPy has confirms that there was no significant bias in the charcoal radiocarbon ages from more recent sedimentary organic matter.
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