Geochemistry Records of Palaeoenvironment from Sanfangwan Neolithic Site in Jianghan Plain, Central China

The culture of Qujialing (5100-4500 cal. a BP) is a representative of Chinese civilization in the Jianghan Plain, middle reaches of the Yangtze River. Nevertheless, limited geochemical data are available on this prehistoric culture in relation to environment in this region. In this study, geochemical records on TOC, TN, C/N ratio and δ 13C extracted from sludge sediments of unit T1610 profile at the Sanfangwan Neolithic site of late Qujialing period (4800-4500 cal. a BP) were integrated to clarify the palaeoenvironment, palaeoecology and human activities during the late Holocene in the Jianghan Plain. The results suggest that palaeo-environment changes in the Sanfangwan site went through three stages (i.e. warm and humid → mild and slightly wet → relatively warm and humid) during the late Qujialing period. C3 plants occupied most parts around the studied area. An overall warm and humid climate around the Sanfangwan site resulted in the establishment of a more stable and predominantly C3 plant forest ecosystems, which have provided effective protections against human impact and climate change and substantively push the development of agriculture that led to the Qujialing culture flourishing. During this period, the emergence of rammed earthen walls and moats of the Sanfangwan site might mark the inception of the Chinese civilization in the Jianghan Plain, middle reaches of the Yangtze River. The geochemical records of palaeoenvironment evolution from the Sanfangwan Neolithic site are in good accordance with those of adjacent area. It responded to regional environmental change of the middle Yangtze River.