HIGH-RESOLUTION CLIMATIC RECORDS OF THE LAST TWO GLACIATIONS:EVIDENCE FROM LOESS-SOIL SEQUENCES,NORTH-CENTRAL CHINA
最后两个冰期旋回季风-沙漠系统不稳定性的高分辨率黄土记录

The Xinzhuangyuan and Lijiayuan loess sections in the northwestem part of the Chinese Loess Plateau were studied down to the paleosol tnt S2, which was formed during the marine oxygen isotopic stage 7. The thickness of the loess-soil sequence above S, is about 63 m at Xinzhuangyuan and 43 m at Lijiayuan. Samples were taken at 2 cm intervals from both of the sections. TIs sample spacing yields a mean depositional resolution of 50-80 years for the last and Penultimare glacial loess layers of L, and Li, and about 200 years for the last interglacial soil unit S1, thus enabling us tO reconstruct high-resolution climatic changes during the last two glacialinterglacial cycles. Grain size was measured on a total of 5 300 samples. The grain-size records are regarded as a proxy of changes in the monsoon-desert system over northern China. ResultS show that frequent large-amplitude climatic oscillations on millennial bine scales occurred during the Penultimare glaciation in a manner similar to that during the last glaciation, suggesting that sub-orbital scale climatic variations may be a common featUre of the climate system during glacial periods of the late Pleistocene. The last interglacial soil S, is composed of three individual soils and tWo thin intervening loess horizons in both of the sections. Short-term variations in grain-size are not prominent within the soil complex, implying the absence of strong millennial -scale climatic oscillations during the last interglaciation in northern China.