Late Quaternary aeolian activity in the Mu Us and Otindag dune fields (north China) and lagged response to insolation forcing

Abstract

[1] Dune fields in parts of northern China contain important stratigraphic records of late Quaternary change in the East Asian monsoon. In this study, 33 new optically stimulated luminescence (OSL) ages and other measurements from aeolian sediment sections are used to reconstruct the timing of wet-dry climate variation in the Mu Us and Otindag dune fields of north China. The results indicate dune activity and dry climate in the last few hundred years, 14 ka to about 7 -8 ka, and 50 ka to 60 ka. The dunes were mainly stable, implying a wetter climate, between about 7 -8 ka and 2.4 ka. These results imply a lag of several thousand years between peak summer insolation at 10-11 ka and high summer monsoon rainfall after 7 -8 ka. In the investigated regions, the monsoon climate may not respond directly to orbital forcing over millennial time scales. Land surface feedbacks may account for lagged dune field response.

Distribution and vegetation reconstruction of the deserts of northern China during the mid‐Holocene

“…The principles underlying our approach are as follows: First, the reconstructed vegetation is an effective tool for understanding the expansion and contraction of deserts. The desert becomes stabilized or contracts when the vegetation cover is enhanced and becomes mobile or expands when the vegetation cover deteriorates [Lu et al, 2005]. For example, the change from desert to steppe vegetation, or from steppe to forest steppe, implies desert contraction, while a change to desert-type vegetation implies desert expansion.…”

“…Episodes of weakened monsoonal circulation would have reduced moisture availability and consequently vegetation cover, resulting in the expansion of broad dune fields and desert [Lu et al, 2005;Qiang et al, 2013].…”

“…However, because most of this work is confined to certain regions with limited availability of sedimentary records and accurate dates, the distribution of desert boundaries varies between different studies, and this needs to be more thoroughly investigated. In addition, little is known about the nature of vegetation change in the deserts of northern China, although this has a dramatic effect on sand mobility [Lu et al, 2005;Qiang et al, 2013] and desertification [Sun, 2000]. Although there are many vegetation reconstructions based on pollen analysis of individual sites in the dry lands of northern China [Gao et al, 1992[Gao et al, , 1993Jiang et al, 2006;Yang et al, 2012;Sun and Feng, 2013], most of these studies focus on climate change over time rather than on spatial patterns.…”

“…The deserts in northern China extend from central Asia and include most of the dry lands located in the marginal zone of the East Asian summer monsoon (EASM), where the vegetation ecosystem and the desert distribution are highly sensitive to climate changes [Lu et al, 2005;Sun et al, 2006]. There are several reconstructions of the desert distribution in China during the mid-Holocene [i.e., Dong et al, 1997;Sun et al, 1998;Jin et al, 2001;Lu et al, 2013;Yang et al, 2013], and they generally agree that the deserts underwent a sharp contraction during the mid-Holocene compared to the present day.…”

Long-term Pleistocene aridification and possible linkage to high-latitude forcing: New evidence from grain size and magnetic susceptibility proxies from loess-paleosol record in northeastern China

“…Thus, the variation of the sand-sized particle fraction in loess deposits near the desert margin is closely linked to the expansion and contraction of areas of sand dune mobility in northern China. Moreover, because the migration of the desert margin is primarily controlled by the amount of monsoon precipitation (Lu et al, 2005;Mason et al, 2009;Sun et al, 1998), the sand-sized particle content in the loess deposits near the desert margin can serve as a useful proxy for the aridity of the dust source areas (Ding et al, 2005).…”