Sandy Loess Records of Precipitation Changes and Monsoon Migrations in the Hunshandake Sandy Land Since the Last Glacial Maximum

Abstract

The Hunshandake Sandy Land (Hunshandake) in central Inner Mongolia, China, is located within the fringe of the East Asian summer monsoon (EASM) domains. Precipitation records in Hunshandake are essential to studying the migrations of the EASM. This work reproduced the precipitation changes since the Last Glacial Maximum (LGM) by measuring the magnetic susceptibility and carbonate content through optically stimulated luminescence dating of two sandy loess profiles within the sandy land to obtain a high‐resolution sedimentary chronological sequence. In addition, eolian topsoil samples were collected along the modern precipitation gradient and their magnetic susceptibility values were compared among the monsoon region, the monsoon marginal region, and the nonmonsoon region. The results demonstrate the following: (1) from 25 to 15 ka, precipitation was low in Hunshandake and exhibited no substantial variability or trend; from 15 to 6 ka, precipitation increased gradually and reached its maximum at approximately 6 ka; and after 6 ka, precipitation decreased again; (2) precipitation changes in Hunshandake since the LGM were mainly determined by the migration of the EASM; and (3) changes in the monsoon migrations in Hunshandake since the LGM are primarily driven by the changes in global ice volume and subordinately by solar radiation.

Magnetoclimatological Record of Late Pleistocene Loess in the Southern Hunshandake Sandy Land, Inner Mongolia: A Threshold Response to the East Asian Summer Monsoon Variations

“…The Hunshandake Sandy Land (HSL), covering an area of about 52,000 km 2 , is one of the four largest sandy lands in central and eastern Inner Mongolia (Figure 1). Quite a few paleoclimatic studies have been conducted on lake sediments and aeolian sand‐paleosol sequences within and surrounding the HSL since the Last Glacial Maximum, focusing on the timing of the Holocene climatic optimum (S. Z. Liu et al., 2015; Mason et al., 2009; Tang et al., 2015; X. P. Yang et al., 2013), moisture variations during the middle–late Holocene (W. Y. Jiang et al., 2006; H. Y. Lu et al., 2011; Xiao et al., 2006), and their forcing mechanisms (S. Z. Liu et al., 2016; Xiao et al., 2006; Y. W. Zhou et al., 2018). However, there is lack of research on the advance and retreat of the EASM on the glacial–interglacial time scales, especially for loess deposits from the monsoonal margin, which are important for improving our understanding of the spatial variability and forcing mechanisms of the EASM on orbital‐to‐millennial‐scale timescales.…”

“…Y. Lu et al, 2011;Xiao et al, 2006), and their forcing mechanisms (S. Z. Liu et al, 2016;Xiao et al, 2006;Y. W. Zhou et al, 2018).…”