MID-HOLOCENE SOIL FORMATION AND THE IMPACT OF DUST INPUT IN THE MIDDLE REACHES OF THE YELLOW RIVER, NORTHERN CHINA

Loess-paleosol sequences of the Chinese Loess Plateau provide important records of the late Pleistocene through Holocene climate change. The mid-Holocene paleosol S0 in the sequence has had limited study. During the Holocene Megathermal between 8500 and 3100 years B.P., there was a warm-wet climate in both the middle reaches of the Yellow River and the middle-lower reaches of the Yangtze River in China. Luvisols (Cinnamon soils) developed in the loess region in the middle reaches of the Yellow River, whereas Ferric-Luvisols (Yellow Brown Earth) formed in the middle-lower reaches of the Yangtze River. Our stratigraphic, micromorphological, and geochemical studies show that the mid-Holocene Luvisols in the middle reaches of the Yellow River developed on the contemporarily accumulated dust. The Ferric-Luvisol in the middle-lower reaches of the Yangtze River formed on the Xiashu Loess of the last glaciation. The difference in pedogenesis between the two regions during the mid-Holocene was caused by continuous eolian dust input into the soil body in the middle reaches of the Yellow River. The addition of the eolian dust caused the soil profile to extend both downward and upward simultaneously. Thus, the degree of pedogenesis was retarded between 8500 and 3100 years B.P. in the middle reaches of the Yellow River.