Out-of-Phase relationship between the summer and winter monsoon variations during the early Holocene

Great differences were observed in previous studies of the relationship between the East Asia summer monsoon (EASM) and winter monsoon (EAWM) due to the scarcity of winter monsoon geological archives. Here we present high-resolution elemental results together with twelve ¹⁴C dates of a 13.5-m terrace sediment on the western Chinese Loess Plateau to infer the monsoon variability since the last deglaciation. Our results indicate that the ratios of Rb/Sr and Zr/Rb are sensitive indicators of chemical weathering and winter wind intensity, respectively, exhibiting significant fluctuations since the last 16 kyr BP. During the last deglaciation, two cold intervals of the Heinrich event 1 and Younger Dryas were characterized by intensified winter monsoon and weakened weathering intensity. In the early Holocene, weakening of the winter monsoon was gradually weakened around 10.7 kyr BP, leading to the abrupt increasing of the chemical weathering around 9.7 kyr BP. The winter monsoon intensity was relatively strong during the early Holocene and decreased gradually afterwards, whereas the summer monsoon intensity reached a maximum during 8-4.5 kyr BP. Such a discrepancy is likely attributable to different impacts of solar insolation and the remnant Laurentide Ice Sheet on the wind and moisture changes.