Geochemical research on prehistorical culture of Yuchisi Site in Mengcheng Ⅱ — Reconstruction of climatic changes and discussion on proxy selection

Application of the new methods of palynology, geochemistry and so on can help researches based on the archaeological profile to break free from the disciplinary limitations that beset cultural relic researches, and provide meaningful information for archaeological research. 230 samples were collected from a 460 cm deep sediment profile named YC1 in the Yuchisi Site in Mengcheng, Anhui Province at an interval of 2 cm. The site contains cultural layers of the Dawenkou Culture and Longshan Culture, aged from 5 050 cal.aB.P. to 4 000 cal.aB.P. Based on the statistical analysis of elements and grain size in the cultural layers of Yuchisi Site in Mengcheng of Anhui, the extent of every index responding to human activities and climate was obtained, and the climatic change of Yuchisi Site from 5 050 cal.aB.P. to 4 000 cal.aB.P. was reconstructed using climatic impacting indexes, such as factor2 from Principle component analysis, Al2O3/SiO2 and clay concentration. Results show that the climate in the Dawenkou Culture (from 5 050 cal.aB.P. to 4 400 cal.aB.P.) was quite warm and wet, but in the Longshan Culture (from 4 400 cal.aB.P. to 4 000 cal.aB.P.) it was quite cold and dry. From the comparison with classical Asian monsoon index (Stalagmitic δ8O records in Dongge Cave) and solar activity, the reasons for climatic change, and the correlation between climatic change and cultures in primitive society were discussed. Based on this study, it is recommended that the climatic proxy that is heavily influenced by human activities should be avoided.