New insights into Holocene dust activity in eastern Uzbekistan

Abstract

Central Asia is a substantial source of long-range-transported dust, yet the historical and geological variability of dust activity in this region remains poorly understood. This study presents a Holocene record of dust activity from a 6.2-m loess section located near Tashkent in the westerlies-dominated region of eastern Uzbekistan, Central Asia. Utilizing the quartz optically stimulated luminescence dating protocol, we employed grain-size analysis and trace-element geochemistry to reconstruct Holocene dust activity. Dating indicated that this section was deposited over the last 9.6 ka. Four grain-size end-member (EM) components were identified, each representing different atmospheric circulation patterns and sedimentary environments. End-member 2, with a modal size of 11.2 μm, likely represents particles transported by upper-level westerlies, while EM 3, with a modal size of 28.3 μm, is associated with near-surface winds linked to dust storms. Zirconium is concentrated in coarse particles, whereas Rb is enriched in finer particles during dust deposition. Therefore, higher Zr/Rb ratios indicate stronger or more distant dust transport; hence, the Zr/Rb ratio is a reliable indicator of dust activity. Holocene dust activity was reconstructed using the EM 3 component and Zr/Rb ratio, revealing several extreme dust-storm events. During the early–middle Holocene (9.6–5 ka), dust activity was stronger but less frequent compared with the subsequent shift to lower intensity but higher frequency dust events. The long-term orbital-scale decline in Holocene dust activity can be attributed to reduced solar insolation and weakening of the Siberian High since the early Holocene. On a centennial to millennial scale, extreme dust-storm events are teleconnected with cold ice-rafted debris events in the North Atlantic. Projections for the coming century suggest that dust activity in eastern Uzbekistan may further decline, accompanied by an increase in precipitation. This study provides new insights into understanding and predicting dust storms in Central Asia.