Multi-proxy evidence for paleoclimate evolution performed on a paleolake sediment core in the East Asian Monsoon Region

Abstract

A sediment succession from a paleolake in the Hangjiahu Plain, Southeast China, covering the period 11.4–5.0 cal ka BP was studied using grain size, total organic carbon (TOC), organic carbon isotope (δ13Corg), C/N ratio, pollen, carbonate and its carbon and oxygen isotopes (δ18Ocarb and δ13Ccarb) analysis to reconstruct climate changes. The methods of redundancy analysis (RDA) ordination and correlation analysis (CA) were employed to quantify the influence of geochemical indexes on the biological index (the pollen) and to explain the environmental significance of each proxy more scientifically and accurately, so as to provide more reliable indication for the reconstruction of the paleoclimate. The reconstruction, supported by the AMS 14C age modelling, indicates climatic evolution during the Early–Middle Holocene period, at least, experienced four stages: (1) a period of gradual warm and humid during the early Holocene (11.4–8.7 cal ka BP). (2) A middle continuous cold–dry stage (8.7–8.0 cal ka BP), precipitation and temperature declined revealed by the proxies. (3) 8.0–6.6 cal ka BP, which was the wettest and warmest stages in the climate change sequence, precipitation, and temperature increased markedly, and this stage was consistent with the Holocene Climate Optimum. (4) A cold–dry period during the middle Holocene (6.6–5.0 cal ka BP), and particularly worth mentioning was that a large number of Oryza pollens were found which indicated the rice-based agriculture developed. In particular, the Liangzhu Culture in this region appeared at this time.