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Chronology of loess-paleosol sequences at Weinan section, Central China

Jiaqi Liu, Sun Jimin, Chen Rui, Wang Wenyuan

Geologos

2000

Vol. 5

165--174

The loess profile at Weinan (34°12’N and 109°31’E), Central China, with good stratigraphic stability and well developed paleosols, was systematically sampled and dated by AMS radiocarbon and TL methods. The preliminary high-resolution time scale of this section has been tuned. Based on this time scale and other climatic proxies such as susceptibility curve and grain-size curve, the author summarizes several for the last 150,000 years age results regarding some important stratigraphic boundaries and established a time scale. According to this time scale, the basal age of S0, located at 143 cm below the top of section, corresponding to the boundary between S0/L1 is 11,980 yr cal BP, this is the age of the beginning of Holocene. The age of the boundary between L1 and S1 is dated 74,220 years B. P. at 854 cm, which shows the ending age of the last interglacial stage is about 74,000 cal BP. Si is highly pedogenised paleosol with dark brown color and 361 cm in thickness. It can be divided into three sub-layers, corresponding to the last interglacial stage, the real S1/L2 boundary is located in 1,180 cm depth and has an age of 128,870 years B. P. It may be correlated with the deep-sea oxygen-isotopic stage 5. The Last Glacial Maximum (LGM) reflected in Weinan loess section by grain size curve and susceptibility curve is from about 20,000 cal BP to 18,000 cal BP. A rapid deposit period from 300 cm to 196 cm lasted a time span from 20,200 cal BP to 19,800 cal BP. The deposit rate of this segment is over 20 times than the average deposit rate of Chinese loess.