Abstracts of Symposium 55 and some papers from other related Symposia.

Pleistocene Chronology and Climatology Based on Grainsize Analysis of a Classic Loess Sequence (China)

Jef VANDENBERGHE & Govert NUGTEREN, Inst. Earth Sciences, Free University, De Boelelaan 1085, 1081 HV Amsterdam, Netherlands,
AN ZHISHENG & LU HUAYU, Xian Laboratory of Loess and Quaternary Geology, P.B. 17, 710061 Xian, China

It is shown that the grainsize characteristics of the loess sequence at Luochuan on the Chinese Loess Plateau are a direct function of climate. After elimination of weathering effects, carefully selected grainsize parameters reflect more specifically the speed of the northerly winter winds (associated with the 'Siberian High'). Grainsize boundaries in the vertical section coincide with known climatic changes for the youngest 250 ka. Given the absolute ages of these boundaries allows to determine sedimentation ratios of the loess. It appears that these sedimentation ratios correspond tightly to the selected grainsize parameters. Since in the Luochuan section, which covers the whole Pleistocene, hiatuses appear to be absent, the established relationship between grainsize parameters and sedimentation ratio allows to calculate the age of any particular layer and to derive its climatic conditions. Furthermore, the characteristics of the summer monsoon, in terms of precipitation and temperature, may be qualitatively estimated from the soil characteristics and the magnitude of the magnetic susceptibility.

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