Mid-Pleistocene environmental reconstruction based on Xiashu loess deposits in the Yangtze Delta, China

A 5.67-m-thick section in loess-like sediments at Xiashu was exposed during archaeological excavation of the Fangniushan Paleolithic site. ESR dating and grain-size analysis suggested that the sediments are wind-blown in origin and were deposited within a period of about 400 kyr. Environmental proxy indicators, including magnetic susceptibility, frequency-dependent magnetism, Kd, median grain size and clay grade percentage show that five warm and humid climatic periods occurred in the study region in the mid-Pleistocene, namely at 130-90, 192, 195-198, 203-230 and 345-357 ka. These five periods roughly correspond to the S1, S2, S3, S4 and S5 paleosols in the Chinese Loess Plateau stratigraphy and also to the deep-sea oxygen isotope stages 5, 7, 9, 11, and 13-15. The upper four climatic periods are comparable to the four warm climatic periods recorded in the Laohushan Xiashu loess section. Discovery of stone implements from the sixth and the seventh layers during the archaeological excavation indicates human activities at that time, and the environmental proxies suggest that the environment was suitable for human activities.