Chinese deserts and sand fields in Last Glacial Maximum and Holocene Optimum

Abstract

The Last Glacial Maximum (LGM, and the Holocene Optimum (HO, c. 9-5 ka) were characterized by cold-dry and warm-wet climates respectively in the recently geological Earth. How Chinese deserts and sand fields responded to these distinctive climatic changes is still not clear, however. To reconstruct environments of the deserts and sand fields during the LGM and HO is helpful to understand the forcing mechanisms of environment change in this arid region, and to test paleoclimatic modeling results. Through our long-term field and laboratory investigations, 400 optically stimulated luminescence (OSL) ages and more than 100 depositional records in the Chinese deserts and sand fields were obtained; on the basis of these data, we reconstruct spatial distributions of the deserts and sand fields during the LGM and HO. Our results show that the sand fields of Mu Us, Hunshandake, Horqin and Hulun Buir in northern and northeastern China had expanded 25%, 37%, 38% and 270%, respectively, during the LGM; the sand fields of Gonghe in the northeastern Qinghai-Tibetan Plateau had expanded 20%, and the deserts of Badain Jaran, Tengger in central northern China had expanded 39% and 29% separately during the LGM; the deserts of Taklimakan, Gurbantünggüt and Kumtag in northwestern China had expanded 10%-20% respectively, compared to their modern areas. On the other hand, all of the sand fields were nearly completely covered by vegetation during the HO; the deserts in northwestern and central northern China were reduced by around 5%-20% in area during this time. Lakes in this arid region were probably expanded during the HO but this conclusion needs more investigation. Compared with the geological distributions of deserts and sand fields, human activity has clearly changed (expanded) the area of active sand dunes at the present time. Our observations show that environmental conditions of Chinese deserts and sand fields are controlled by regional climate together with human activity. deserts and sand fields in China, Last Glacial Maximum, Holocene Optimum, OSL dating, active sand dunes Citation:

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

“…However, our results suggest that the desert shifted northwestward to near the present-day 300 mm isohyet (bold red line in Figure 4), which suggests a degree of retreat which differs to that proposed by Dong et al [1997], Jin et al [2001], Zhou et al [2002], and Lu et al [2013].…”

“…Third, we suggest that our study represents a significant advance in that vegetation records that were combined with sedimentary facies records in order to reconstruct the spatial distribution of desert. In contrast, previous studies have focused mainly on sedimentary facies [Dong et al, 1997;Jin et al, 2001;Zhou et al, 2002;Lu et al, 2013]. Therefore, we suggest that our reconstruction provides a more comprehensive spatial distribution of desert in northern China during the mid-Holocene.…”

“…We compared our reconstruction of the distribution of deserts during the mid-Holocene with the results of previous studies [Dong et al, 1997;Jin et al, 2001;Zhou et al, 2002;Lu et al, 2013] (Figure 4). There is a general agreement that the deserts exhibited a major northwestward contraction compared to their modern distribution.…”

“…First, there is a lack of consistency in previous studies in the definition of the mid-Holocene. For example, it was defined as 7.5-3 Ka B.P by Jin et al [2001], 7.5-4 Ka B.P by Dong et al [1997], and 9-5 Ka B.P by Lu et al [2013]. This relatively broad range would have encompassed a significant amount of climatic variability resulting in corresponding differences in the location of the desert boundaries.…”

“…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. 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.…”