Geochemical evidence for changes in provenance and paleoclimate during the Holocene obtained from a fluvial–eolian sequence in the southern Mu Us Desert, north-central China

• Published in: Geoderma 2024-04, Vol.444, p.116860, Article 116860
• Main Authors: Ding, Zhiyong, Lu, Ruijie, Fan, Xuanmei, Liu, Xiaokang, Pu, Jia, Shen, Yaping, Zhang, Jianpeng
• Format: Article
• Language: English
• Subjects: Fluvial–lacustrine–aeolian sequences; Geochemistry; Holocene; Mu Us Desert; Paleoenvironment
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/j.geoderma.2024.116860

•New geomorphological and geochemical records from the southern Mu Us Desert (MUD), northern China.•The sources of southern MUD sediments have evident temporal variation.•Early–Mid-Holocene southern MUD sediments are mainly derived from a local source.•The maximum CIA occurs at 8.4–6.4 ka BP and is related to enhanced monsoonal rainfall.•Late-Holocene mixed sources in the southern MUD are associated with an enhanced winter monsoon.•Summer and winter monsoons alternate in controlling the sediment source and geomorphic evolution in the southern MUD. Identifying the sources and weathering degree of sediments in the northern deserts of China is crucial to understand the evolution of the Asian monsoon system and corresponding induced changes in surface processes. Great progress has been made in the reconstruction of paleoclimate and paleoenvironment from the Early Holocene onwards based on chronostratigraphy and proxies of aeolian sedimentary sequences in the Mu Us Desert (MUD). However, previous studies have given rise to some controversial over the timing of the Holocene optimum period, and there is a scarcity of studies on the sediment provenance evolution of the desert during the Holocene and its internal relationship with the East Asian summer (EASM) and winter (EAWM) monsoons. Here, we provide new elemental geochemical data from a fluvial–aeolian sedimentary sequence in the southern MUD; we then combine these data with other available elemental data and hydroclimatology information to investigate the characteristics of sediment source evolution and their possible connection with the EASM and EAWM on the southern margin of the MUD-desert/loess transition zone since the latter part of the Early-Holocene. The elemental composition and geochemical characteristics of the studied sedimentary sequence differed markedly in the periods before and after 6.4 ka BP, suggesting a change in the source of the sediments across this boundary. From the late Early-Holocene (10.6 cal. ka BP), sediments were dominated by the chemical weathering products of local source material, with a gradual increase in chemical weathering over time, indicating a gradual strengthening of the EASM; the EASM reached its peak Holocene strength at 8.4–6.4 ka BP, accompanied by a moderate level of chemical weathering. After 6.4 ka BP, with the weakening of monsoon precipitation, the EAWM began to strengthen, and long-distance transport of source material from the west and northwest increased; ho