Orbital tuned time scale for loess deposit in Luochuan of central Chinese Loess Plateau

The loess-paleosol profile in Luochuan of central Chinese Loess Plateau was sampled every 5cm in loess layers and 3cm in palaeosol layers, all samples were measured for magnetic susceptibility which is regarded as an excellent proxy index of East Asian summer monsoon variations during the Quaternary. On the basis of astronomical theory of Pleistocene climatic changes, we calibrated this loess palaeosol sequence by tuned to the orbital records calculated by Berger and Loutre (1991) under the control of major magnetic reversals. The results show that the age of Brunhes/Matuyama boundary is 772ka B.P.; The age of boundary between Lishi and Wucheng loess deposit is 1 348 ka B.P. and loess has deposited since 2 471ka B.P. This new time scale is tested by comparing the ages of magnetic reversals estimated from our time scale with the ages determined by Cande and Kent (1992) and the cross spectral analysis of two time series. The results show that the new time scale is reliable.