New chronology of the Chinese loess-paleosol sequence by leaf wax delta D records during the past 800 k.y.

The Chinese loess-paleosol sequences provide important archives for studying paleoenvironmental changes. However, the lack of independent and accurate time scales hinders the study between loess and other records. Asian stalagmite delta O-18 records indicate synchronous patterns of paleoprecipitation delta O-18 over large geographic regions. The record of hydrogen isotopic composition of plant wax (delta D-wax) in Chinese loess is also controlled by rainwater delta D. Both share a common origin. The linear relationship between rainfall delta O-18 and delta D variance provides the basis to tie together chronologies of the same climate event in different records. Here, we show a new loess chronology by correlating chronologies of marker boundaries of the prominent climate chronozones in stalagmite delta O-18 and summer insolation to the equivalent climate stratigraphy in the loess delta D-wax sequence. We first developed and tested this novel methodology with data since the last interglacial on a millennial scale, and then applied this approach to the loess delta D-wax sequence for the past 800 k.y. to improve the traditional chronology based on magnetic susceptibility and grain size. The new delta D-wax time series provides not only an improved chronology for studying paleoclimate changes during interglacial intervals, it also represents a unique database with which to better understand the links between the Asian monsoon changes in the Chinese loess and other global climate events, especially for the periods prior to 640 ka, for which stalagmite records are not available