Early Holocene multi-centennial moisture change reconstructed from lithology, grain-size and chemical composition data in the eastern Mu Us desert and potential driving forces

Abstract

The sequence of paleo-aeolian sands and sandy paleosols from the Shenmu section in the eastern Mu Us desert was used to reconstruct the history of moisture change during the early Holocene. Analyses of lithologies, grain-size distributions and elemental compositions revealed that the early Holocene climate in the eastern Mu Us desert experienced at least seven multi-centennial oscillations between humid and arid episodes. Four humid episodes occurred at 10,800 to 10,200cal. (calendar) yr BP, 9800 to 9400cal.yrBP, 8900 to 8300cal.yrBP and 8000 to 7700cal.yrBP. Three arid episodes occurred at 10,200 to 9800cal.yrBP, 9400 to 8900cal.yrBP, and 8300 to 8000cal.yrBP. These humid-arid oscillations were representative of multi-centennial fluctuations in the history of waxing and waning of the East Asian summer monsoon (EASM) and the East Asian winter monsoon (EAWM) in the eastern margin of the Mu Us desert. Comparisons with other climate records based on pollen-based annual precipitation (PANN) reconstructed from Gonghai Lake and the stalagmite δ18O records from Dongge cave, southern China, supported certain influences of the Indian summer monsoon on moisture variations in the eastern margin of the Mu Us desert. Our results also revealed a possible climatic connection between the variability of the East Asian winter monsoons and air temperature changes at high latitudes in the northern hemisphere and North Atlantic thermohaline circulation during the early Holocene. The similarity between early Holocene climate evolution in the eastern Mu Us desert and several proxies (∆14C residuals, sunspot numbers, spectral analysis of grain-size and elemental compositions) supports the hypothesis that variations in solar insolation are a major external force responsible for East Asian Monsoon variations at the multi-centennial scale during the early Holocene.