Fine aeolian quartz records in Cheju Island, Korea, during the last 6500 years and pathway change of the westerlies over east Asia

摘要

We investigated the fine component of aeolian dust deposited on a maar of Cheju Island, Korea, during the last 6500 years to specify the variability of fine aeolian dust transported by the westerlies and its main controlling factor from the viewpoint of global atmospheric circulation. As a proxy for the fine aeolian dust, we used the fine component of chemically isolated aeolian quartz from bulk sediments. The fine quartz flux (FQF) varies from 0.1 to 1.4 mg/cm2/a with periodicities of 1620, 810, 400, 325, and 210 years, mainly providing information on the aridity change in the dust source region (the Taklimakan Desert). The median grain size of the fine quartz (MFQ) representing the pathway of the dust-transporting westerlies fluctuates between 2 and 6 μm with significant cycles of 1030, 390, 280, 220, and 195 years and shows similar variation pattern to the FQF. On the basis of visual and spectral analyses, the high/low FQF and the large/small MFQ correspond to the warm/cold atmospheric temperature record from Greenland ice cores with significant coherent cycles, indicating that the aridity in the dust source areas and the pathway of the westerlies in east Asia were linked to climatic and atmospheric conditions in Greenland through the pathway change of the westerlies. During the middle to late Holocene, the pathway change of the westerlies mainly responsible for the variability of the fine aeolian dust in east Asia was probably controlled by a climatic response to initial solar activity and resulting atmospheric reorganization in polar and high-latitude regions.