An OSL-dated, stacked Holocene dust mass accumulation rate record on the Chinese Loess Plateau and its implications for Northern Hemisphere dust activity

Abstract

Accurate reconstruction of geological dust activity is crucial for understanding past climate change and its interaction with dust cycle. Loess on the Chinese Loess Plateau (CLP) is an ideal and sensitive material for revisiting past dust activity. Previously, the changes in the dust mass accumulation rate (MAR) over various time scales were widely established on the CLP. However, few absolutely dated dust records have been obtained and synthesized for the Holocene. This study addresses this gap by compiling 23 optically stimulated luminescence-dated Holocene loess sections across the CLP. We developed a high-quality chronology via Bayesian age-depth modeling and derived a MAR record for each section. Then, we obtained a mean MAR record for the CLP by stacking individual records. We propose that, in contrast to site-specific MARs, stacked MARs represent the mean dust accumulation conditions for the entire CLP and can be used to track relatively large-scale dust activity and climate change. The stacked MAR record suggests a moderate weakening trend of dust accumulation from ∼11.5 to 7.5 thousand years ago (ka BP), followed by a pronounced strengthening trend from ∼7.5 to 3.0 ka BP. A comparison with other regional dust records reveals a shift in dust activity at ∼8–6 ka BP in northern China and western Mongolia. We argue that the East Asian winter and summer monsoons jointly contributed to Holocene mean dust MAR variations on the CLP by changing dust transport wind energy and dust source aridity, respectively. A comparison of Holocene dust records in Asia with those in the northwestern Pacific Ocean and Greenland suggests asynchronous variations in dust activity between proximal and distal Asia-sourced dust deposition. This is because, unlike proximal deposition, distal deposition can be controlled not only by the dust source conditions but also by the intensity and the position of the Westerlies.