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

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 15ka, precipitation was low in Hunshandake and exhibited no substantial variability or trend; from 15 to 6ka, precipitation increased gradually and reached its maximum at approximately 6ka; and after 6ka, 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.