부산대학교 도서관

Different from fine silt dominated classic loess on the southern and central Chinese Loess Plateau (CLP), coarse sandy loess is widely distributed along the southern bank of the middle Yellow River, which is up to approximately 100 m thick. However, its deposition time and formation processes are still unclear. Here, three representative sandy loess sections in the middle Yellow River were dated using the singlealiquot regenerative-dose (SAR) optically stimulated luminescence (OSL) and recuperated OSL (ReOSL) protocols on fine quartz grains (4-11 µm). The validity of these two protocols was robustly verified through conventional checks in luminescence dating. Our dating results showed that the sandy loess was mainly deposited within the last glacial period, with extremely high dust accumulation rate, which was much larger than that of the classic loess in the southern and central CLP. With respects to atmospheric circulation and geomorphology settings, and grain size and magnetic susceptibility results from both the sandy loess and surface sediments from the Yellow River beds and fluvial plains, it is suggested that the sandy loess was dominantly sourced from the proximal fluvial sediments of the Yellow River, transported by the northerly East Asian winter monsoon (EAWM) winds. During the last glacial period, the East Asian summer monsoon (EASM) was weak with low rainfall in central and northern China, which led to reduced runoff and vegetation cover in the middle Yellow River valley. Therefore, the river beds and fluvial plains promoted sufficient dust material supply. Finally, the dust was transported by the strong EAWM winds and deposited along the southern bank of the middle Yellow River, which resulted in the formation of the thick and high-sedimentation-rate sandy loess. Our study highlights the significance of the interactions between aeolian and fluvial processes at sandy loess deposition in the middle Yellow River and also implies the potential of the investigated sandy loess at high-resolution paleoclimate reconstruction. [ABSTRACT FROM AUTHOR]