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 p aleoclimatic reconstructions, but also permit the establishment of a r eliable absolute time scale for the Quaternary, An empirical relations hip is developed between the grain size of the loess and the sedimenta tion rate in a short, well-dated reference section (step 1). This rela tionship is extrapolated to the complete Quaternary section (step 2). After derivation of the sedimentation rate (by measuring the grain siz e) in all the lavers of the sequence, the duration of deposition of ea ch 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 wa y is independent of dates provided by other methods and may also be ch ecked by them.