Application Of Black Carbon Purification With HydroPyrolysis In Determining The Lower Limit Of Liangzhu Culture

Located at the middle and lower reaches of the Yangtze River around the Lake Tai, Liangzhu Culture is one of the most important Neolithic cultures of China. As a representative of the dawn of Chinese civilization, it provides significant evidence with which to trace the multiple sources of Chinese civilization. However, the controversy on the lower limit of Liangzhu age damages the reading of the upper limit and definition of the prehistoric culture. In order to obtain an accurate lower limit of Liangzhu Culture, in this study, buried ancient charcoals and wooden stakes were collected from the continuous sedimentary profile of Bianjiashan wharf in Hangzhou City, Zhejiang Province, Eastern China. According to the proof of culture characters and AMS I4C data, the timescale of the late Liangzhu Culture has been finally determined. In consideration of the high purity requirement on the AMS dating materials, the wooden stakes were preprocessed by standard acid-alkali-acid procedure and the charcoals were pretreated by HydroPyrolysis (HyPy) technique to get rid of even trace amounts of contamination. From the dating results of wooden stakes and charcoal HyPy residues in the bottom layer, the wharf is confirmed to be built no later than4770±30yrBP, which is proximate to the formation of river sediments.14C age of charcoal HyPy residues in the top layer suggests that the collapse of the Laingzhu Culture should date back to no earlier than4420±30yrBP, and this is the same time with the end of river evolvement. So the lower age span of Liangzhu Culture is from4770±30yrBP to4420±30yrBP. According to further molecular characterization on the HyPy products and the relevant DCM extractable oil by GC-MS, it can be deduced that the main source of pollution may be from the terrigenous higher plants degradation. HyPy is a robust approach not only for isolation of dating target BC with stable thermal-chemical structure but also in characterization of removed contaminations. It definitely has further popularization values. In this study, HyPy pretreatment is firstly attempted in the current domestic archeology.