Aeolian activity in the south margin of the Tengger Desert in northern China since the Late Glacial Period revealed by luminescence chronology

摘要

Aeolian sediments from deserts in northern China have been widely used in the study of aeolian sedimentology and its dynamic association with past climate conditions. The Tengger Desert, the fourth-largest desert in China, is sensitive to the waxing and waning of the Asian monsoonal system. Previous attempts to date aeolian deposits in the Tengger Desert concentrated solely on local scales, and only a limited number of dates have subsequently been made available. Accordingly, past sand dune activity in this desert remains poorly understood. The aim of this study was to conduct a detailed historical investigation of aeolian activity in this region since the late glacial period and potential forcing mechanisms that governed the desert's evolution. For this purpose, we collected and dated eighteen samples from different geological sections along a west-east transect in the desert's southern margin using optically stimulated luminescence (OSL). Our results, in combination with previous aeolian sediment chronologies, show that sand dune accumulation occurred before 10 ka, sandy loess developed between 10 and 6 ka when sand dunes stabilized as a result of increased effective moisture levels, and sand dunes again mobilized from 3 ka onwards as a result of increased aridity. Findings indicate that aeolian activity at the southern margin of the Tengger Desert was closely associated with Asian monsoon circulation. Moreover, the transition between mobilization and stabilization of sand dunes demonstrates the significance of effective moisture, which is influenced by both monsoon precipitation and local convection and evaporation effects, interacting together to control aeolian activity. (C) 2016 Elsevier B.V. All rights reserved.