QUANTITATIVE ESTIMATES OF PALAEOPRECIPITATION AT XIFENG, IN THE LOESS PLATEAU OF CHINA

Using Be-10, recent studies (Heller et al., 1993; Beer et al., 1993) have tried to reconstruct palaeoclimatic records by separating the secondary (pedogenic) and primary (aeolian; detrital) contributions to the magnetic susceptibility of Chinese loess. Here we use a technique, which monitors the temperature dependence of magnetic remanence, to estimate the magnetisation and relative contribution of the superparamagnetic (SP), single-domain (SD) and multidomain (MD) ferrimagnetic components in the Xifeng loess section. On the assumption that the SP ferrimagnetic component is dominantly of pedogenic origin, the magnetisation of this component has also been determined for samples taken from the topmost palaeosol (SO), at six sites over the Loess Plateau, and directly correlated with present day precipitation at these sites. This correlation is then used to estimate quantitatively palaeoprecipitation for the topmost 16 m of the Xifeng section, which covers about the last 140,000 years. The data indicate a considerably reduced precipitation during the glacial, loess-forming periods and a significantly higher level of precipitation than today during the last interglacial period.