9:30 AM - 9:45 AM
[HQR05-03] Climatic and vegetational changes during and before the period of the Hemudu Culture, China in the Yaojiang plain shown by biomarker compositions
Keywords:Hemudu , rice cultivation, archaeology, biomarker
Ancient people of neolithic cultures in lower Yangtze, China accomplished rice domestication by 5000 BP. Especially, rice domestication greatly progressed in Hemudu culture(ca 7000 to 5000 BP) which emerged at the same time of forming Yaojiang plain. Many studies that focused on the relationship between this domestication process and environmental changes are performed. But reliably dated reconstruction of paleoclimate and paleovegetation are unavailable. This problem hinders progress of Hemudu culture study. In this study, we obtained high temporal resolution paleoenvironmental records from sediments of boreholes near two archaeological sites using biomarkers and compared microfossil assemblage. The detail linkage between climate changes, paleovegetation and life history of Hemudu culture people was comprehensively discussed.
The present study shows biomarker results from the core named TK(obtained from neighborhood Tianluoshan Site) and the core named HK(obtained from plain located northern Hemudu Site). We investigated 14C ages of plant fragments and shells, pentacyclic triterpene methyl ethers (PTMEs) of Gramineae origin, glycerol dialkyl glycerol tetraethers (GDGTs), polycyclic aromatic hydrocarbons (PAHs), δD, and δ13C both from long-chain fatty acids, in order to reconstruct paleoenvironment and climate of the Yaojiang Plain during and before the Hemudu Culture. And also, we compared phytolith(Udatsu et al.), pollen and diatom (Kanahara et al.) assemblage from the same cores.
The ratio of Arundoin and Cylindrin to the total PTME was high in the rice paddy layer of both site(TK: 7000-6400BP, After 6200BP; HK: 6800-6700BP). The value of [Cylindrin] / [Arundoin] in the underlying layer (8200 - 7400 BP) was similar to that of HK paddy layer. Arundoin and Cylindrin are detected from Oryza by previous studies. Recent stadies showed oryza pollen and phytolith record before culture pirod, and we could obtain new Oryza vegetation record by biomarker.
The amount of GDGT - 0,1,2,3 and the ratio of them to GDGTs were high in core HK paddy layer. Methanogen produce GDGT-0 and ANME produce GDGT-0,1,2,3, and they thrive in flooded paddy fields. This result supports the idea that there were waterlogged paddy field.
In Core HK paddy layer, the amount of Reten was high. The value of DMP - x was low in lower part of the layer and high in upper part of that. Reten derives from conifer combustion. DMP - x index shows low value when hardwood were combusted and high value in the case of leaves and straw. The ratio of Phenanthrene/Anthanthrene, Benz[a]anthracene/Chrysene were similar to the value of burnig rice straw experiments limited to paddy layer. Woods combustion episode relates to fire clearing. Our buring rice straw record is older than that of Majiabang culture study.
The high resolution wax δD value showed low value in lower parts of two paddy layers(ca 7 Ka, and 6 Ka). The δD value of recipitation in this area is low when climate is humid. At the beginning of rice farming, climate was humid. It is consistent with rough resolution climate reconstruction by pollen records from lower Yangtze. Our conclusion is opposite to Patalano et al.(2015) that drying event made it possible to farm rice.
The above results are high resolution paleoenvironmental reconstruction during and before Hemudu culture in Yaojiang plain, and help us to understand domestication process of rice and neolithic culture.
References
Li, J., Dodson, J., Yan, H., Wang, W., Innes, J. B., Zong, Y., Zhang, X., Xu, Q., Ni, J., & Lu, F. (2018). Quantitative Holocene climatic reconstructions for the lower Yangtze region of China. Climate Dynamics, 50(3-4), 1101-1113. https://doi.org/10.1007/s00382-017-3664-3
Patalano, R., Wang, Z., Leng, Q., Liu, W., Zheng, Y., Sun, G., & Yang, H. (2015). Hydrological changes facilitated early rice farming in the lower Yangtze River Valley in China: A molecular isotope analysis. Geology, 43(7), 639-642. https://doi.org/10.1130/G36783.1
The present study shows biomarker results from the core named TK(obtained from neighborhood Tianluoshan Site) and the core named HK(obtained from plain located northern Hemudu Site). We investigated 14C ages of plant fragments and shells, pentacyclic triterpene methyl ethers (PTMEs) of Gramineae origin, glycerol dialkyl glycerol tetraethers (GDGTs), polycyclic aromatic hydrocarbons (PAHs), δD, and δ13C both from long-chain fatty acids, in order to reconstruct paleoenvironment and climate of the Yaojiang Plain during and before the Hemudu Culture. And also, we compared phytolith(Udatsu et al.), pollen and diatom (Kanahara et al.) assemblage from the same cores.
The ratio of Arundoin and Cylindrin to the total PTME was high in the rice paddy layer of both site(TK: 7000-6400BP, After 6200BP; HK: 6800-6700BP). The value of [Cylindrin] / [Arundoin] in the underlying layer (8200 - 7400 BP) was similar to that of HK paddy layer. Arundoin and Cylindrin are detected from Oryza by previous studies. Recent stadies showed oryza pollen and phytolith record before culture pirod, and we could obtain new Oryza vegetation record by biomarker.
The amount of GDGT - 0,1,2,3 and the ratio of them to GDGTs were high in core HK paddy layer. Methanogen produce GDGT-0 and ANME produce GDGT-0,1,2,3, and they thrive in flooded paddy fields. This result supports the idea that there were waterlogged paddy field.
In Core HK paddy layer, the amount of Reten was high. The value of DMP - x was low in lower part of the layer and high in upper part of that. Reten derives from conifer combustion. DMP - x index shows low value when hardwood were combusted and high value in the case of leaves and straw. The ratio of Phenanthrene/Anthanthrene, Benz[a]anthracene/Chrysene were similar to the value of burnig rice straw experiments limited to paddy layer. Woods combustion episode relates to fire clearing. Our buring rice straw record is older than that of Majiabang culture study.
The high resolution wax δD value showed low value in lower parts of two paddy layers(ca 7 Ka, and 6 Ka). The δD value of recipitation in this area is low when climate is humid. At the beginning of rice farming, climate was humid. It is consistent with rough resolution climate reconstruction by pollen records from lower Yangtze. Our conclusion is opposite to Patalano et al.(2015) that drying event made it possible to farm rice.
The above results are high resolution paleoenvironmental reconstruction during and before Hemudu culture in Yaojiang plain, and help us to understand domestication process of rice and neolithic culture.
References
Li, J., Dodson, J., Yan, H., Wang, W., Innes, J. B., Zong, Y., Zhang, X., Xu, Q., Ni, J., & Lu, F. (2018). Quantitative Holocene climatic reconstructions for the lower Yangtze region of China. Climate Dynamics, 50(3-4), 1101-1113. https://doi.org/10.1007/s00382-017-3664-3
Patalano, R., Wang, Z., Leng, Q., Liu, W., Zheng, Y., Sun, G., & Yang, H. (2015). Hydrological changes facilitated early rice farming in the lower Yangtze River Valley in China: A molecular isotope analysis. Geology, 43(7), 639-642. https://doi.org/10.1130/G36783.1