Timing and spatial distribution of mid-Holocene drying over northern China: Response to a southeastward retreat of the East Asian Monsoon

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Abstract

[1] To determine the timing and spatial distribution of mid-Holocene drying over northern China, the mineralogical and oxygen isotopic composition of authigenic carbonate from a closed lake at Bayanchagan, southern Inner Mongolia, were measured. Further analysis and synthesis of the spatial geological data were performed. Results from Lake Bayanchagan show a significant drying at 6000 calendar years (cal years) B.P., indicated by dolomite precipitation and a striking rise in δ18O values. The synthesis of spatial data reveals a zonal distribution for timing of drying over northern China in the mid-Holocene, which began at 9000–7000 cal years B.P. in deserts of north-central China. At 7000–5500 cal years B.P., drying extended into the desert-steppe transitional zone and at ∼4500 cal years B.P. into northeastern and south-central China. This pattern indicates that the east Asian summer monsoon has significantly retreated southeastward since the mid-Holocene, which may be related to orbitally induced Northern Hemisphere insolation changes. A retreat of ∼400–550 km is inferred for the front of the summer monsoon from 6500 to 4500 cal years B.P.

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