Holocene water-level changes inferred from a section of fluvio-lacustrine sediments in the southeastern Mu Us Desert, China

Abstract

A natural exposure of fluvio-lacustrine sediments (the DSGL section) on the left bank of Salawusu River, located at the southeastern margin of the Mu Us Desert in North China, was studied in order to reconstruct Holocene water-level changes. A chronology was established based on 11 AMS 14C dates, and variations in the lithology and grain-size C-M variations were used to assess the forcing factors of local hydrological changes during the Holocene. A lake-swamp environment with high hydrodynamic energy occurred from 9.6 to 9.2 ka cal yr BP, which was succeeded by a full lake environment at around 9.6 ka cal yr BP; however, an interval of sand deposits and peat sediments from 9.2 to 8.6 ka cal yr BP indicates unstable hydrodynamic conditions. The Salawusu paleo-lake reached its maximum level between 8.4 and 6.5 ka cal yr BP and gradually shrank thereafter. After 1.2 ka cal yr BP a shallow lake environment returned, indicating a humid phase which may be correlative with the relatively warm and moist Medieval Warm Period (MWP). After 0.68 ka cal yr BP, broadly coeval with the Little Ice Age (LIA), a fluvial environment appeared. The variations in water level were mainly triggered by the East Asian monsoon; however, site-specific factors may have also have been important.