Origin of Asian dust reconstructed from the Eu anomaly in the Hanon paleo-maar sediment of Jeju Island, Korea

Abstract

In downwind regions, Asian dust fluxes are influenced by aridity and expansion of the source area, as well as by the frequency of dust storms associated with the predominant westerly jet and East Asian winter monsoon (EAWM). This study investigated the origin of Asian dust, and factors affecting its intensity, through analysis of the Hanon paleo-maar sediment of Jeju Island, Korea, using the Eu anomaly as a dust proxy. Trachybasalt (as an end-member) normalization pattern from the Hanon sediment core showed that the (Eu/Eu*)trachybasalt values were lower (0.85 on average) from the pre-Last Glacial Maximum (Late Pleistocene, 32.8–25.9 ka) to the early deglacial period (16.8–14.8 ka), indicating that most of the dust originated from the Gobi Desert. During the late deglacial period (14.5–11.6 ka), the (Eu/Eu*)trachybasalt increased to 0.88 on average, which indicated a gradual change in Asian dust origin toward the Taklimakan Desert and a consequently higher (Eu/Eu*)trachybasalt (> 0.9) during the Holocene period (after 10.2 ka). Asian dust proportion in the Hanon sediment core was around 20–70% during the last glacial period (32.8–11.6 ka), but decreased to 10–30% during the Holocene as the East Asian summer monsoon (EASM) expanded toward north and northeast China. Consequently, provenance changes in dust transport indicate that Asian dust flux associated with the surface EAWM intensity is overall greater during the last glacial period, while the dust transported via the upper level westerly jet could reach the study region during the Holocene.