New absolute time scale for the Quaternary climate in the Chinese loess region by grain-size analysis

Continuous loess sequences in China provide not only information for paleoclimatic reconstructions, but also permit the establishment of a reliable absolute time scale for the Quaternary. An empirical relationship is developed between the grain size of the loess and the sedimentation rate in a short, well-dated reference section (step 1). This relationship is extrapolated to the complete Quaternary section (step 2). After derivation of the sedimentation rate (by measuring the grain size) in all the layers of the sequence, the duration of deposition of each layer is obtained (by dividing thickness by sedimentation rate) and subsequently the age of each point in the sequence is calculated (by adding together all the duration values of the overlying layers). The chronology of the extrapolated part of the section obtained in this way is independent of dates provided by other methods and may also be checked by them.