Abrupt environmental changes during the last 30 kyr in the southern margin of the Taklimakan Desert, a record from an oasis

Abstract

The Taklimakan Desert, the largest sand sea in China, is one of the most important sources of dust in the world. Millennial-scale abrupt climate changes during the last glacial and Holocene periods occurred in the region. However, these records remain poorly understood because dating eolian, lacustrine, and fluvial sediments and establishing reliable environmental proxies are challenging in this setting. Here, we use accelerator mass spectrometry (AMS), grain size, and Rb/Sr ratios of bulk sediments from an oasis sequence in the Taklimakan Desert. While some 14C dates results are not in the stratigraphic order, most of them can be grouped in four age groups during the Last Glacial. We infer that reversals of radiocarbon age based on total organic carbon (TOC) was controlled by organic carbon (OC) input from the regional carbon pool. We selected 14C dates from the four age groups, to develop an age-depth model for a basin-wide chronology. Peaks in a cumulative probability curve of radiocarbon dates, with high Rb/Sr ratios and fine mean grain sizes, reveal four wet periods during the Last Glaciation, and one wetter/warmer period during the Holocene. The regional moisture variability appears to be influenced by the Asian summer monsoon and mid-latitude Westerlies. The Holocene wetter/warmer period facilitated human occupation of the oasis.