Out-of-phase evolution between summer and winter East Asian monsoons during the Holocene as recorded by Chinese loess deposits

Abstract

We analyzed climate proxies from loessic-soil sections of the southern Chinese Loess Plateau. The early Holocene paleosol, S0, is 3.2 m thick and contains six sub-soil units. Co-eval soils from the central Loess Plateau are thinner (~ 1 m). Consequently higher-resolution stratigraphic analyses can be made on our new sections and provide more insight into Holocene temporal variation of the East Asian monsoon. Both summer and winter monsoon evolution signals are recorded in the same sections, enabling the study of phase relationships between the signals. Our analyses consist of (i) measurements of magnetic properties sensitive to the production of fine-grained magnetic minerals which reflect precipitation intensity and summer monsoon strength; and (ii) grain-size analyses which reflect winter monsoon strength. Our results indicate that the Holocene precipitation maximum occurred in the mid-Holocene, ~ 7.8–3.5 cal ka BP, with an arid interval at 6.3–5.3 cal ka BP. The winter monsoon intensity declined to a minimum during 5.0–3.4 cal ka BP. These results suggest that the East Asian summer and winter monsoons were out of phase during the Holocene, possibly due to their different sensitivities to ice and snow coverage at high latitudes and to sea-surface temperature at low latitudes.

Long-term weakening of the East Asian summer and winter monsoons during the mid- to late Holocene recorded by aeolian deposits at the eastern edge of the Mu Us Desert

“…The thick palaeosol developed during the mid-Holocene of the Jinjie section agrees well with the previously-documented widespread palaeosol development in the Mu Us Desert(Sun et al, 2006a;Xu et al, 2013;Jia et al, 2015) and in the eastern sandy lands of China(Lu et al, 2005(Lu et al, , 2013bMason et al, 2009;Li et al, 2014) (Figure 7j). Widespread palaeosol development in the sandy lands of northern China, and on the CLP during the mid-Holocene, in contrast with sand or loess deposits during the late Holocene indicates a stronger EASM in the mid-Holocene than in the late Holocene(Li et al, 2014;Wang et al, 2014). Aeolian sand deposited prior to 7.5 ka for the Jinjie section is in accord with the prevalent early Holocene dune mobility and aridity in the sandy lands (Mu Us, Otindag, Horqin and Hulun Buir) of northern China(Lu et al, 2005;Mason et al, 2009;Li et al, 2014).…”

“…But, there are also some studies showed that the two monsoon systems were neither in-phase nor anti-phase during the Holocene. Based on variations in magnetic properties and grain-size of loess deposits on the CLP, Xia et al (2014) suggested that the EASM and EAWM were out-of-phase during the Holocene, and that the EASM maximum preceded the EAWM minimum by about 2.8 ka. Research on Hongyuan swamp in the…”

“…However, the environmental significance of stalagmite oxygen isotope is debated (Maher, 2008;Clemens et al, 2010;Wang et al, 2014;Liu et al, 2015) and in fact numerous other EASM records are in disagreement with the stalagmite oxygen isotope records. For example, pedogenesis in the CLP (Wang et al, 2014) and in the sandy lands in northern China (Lu et al, 2005(Lu et al, , 2013bSun et al, 2006a;Mason et al, 2009;Xu et al, 2013;Li et al, 2014) documents an EASM maximum during the mid-Holocene, while stalagmite oxygen isotope records (e.g. Dykoski et al, 2005) record a strongest EASM during the early Holocene.…”

“…On glacial-interglacial time scales, the EAWM is thought to have been linked to Northern Hemisphere ice volume via the influence of the Siberian High (Ding et al, 1995), while the EASM was greatly influenced by sea level via its effect on moisture transport distance from the sea (Hao et al, 2012;Li et al, 2014), and that the role of direct local insolation was less important. However, because the glacial boundary conditions can be regarded as similar to the modern state, and both the Northern…”

“…cal ka BP (Xia et al, 2014). A synthesis of grain-size data from well-dated loess sections on the CLP suggests a stronger EAWM during the early Holocene than during the late Holocene (Stevens et al, 2007).…”