Quartz OSL chronology and dust accumulation rate changes since the Last Glacial at Weinan on the southeastern Chinese Loess Plateau



The fine-grained (4–11 μm) quartz Optically Stimulated Luminescence (OSL) dating technique was applied to the Weinan section on the southeastern Chinese Loess Plateau (CLP) with a high luminescence sampling resolution (10- and 20-cm intervals). Fifty-eight OSL ages, spanning c. 1–74 ka, were obtained for the 10-m loess–palaeosol sequences. The reliability of the OSL dating and the constructed chronology was confirmed by comparing the OSL ages with independent dates from other studies and by correlation with palaeoclimatic time series. The closely spaced OSL ages at Weinan indicate that the mean dust accumulation rate (DAR) of L1–1 (MIS 2, 7.0±0.9 cm ka−1) is lower than those of L1–3 (MIS 4, 19.1±6.1 cm ka−1) and L1–2 (MIS 3, 16.0±0.7 cm ka−1) and that the mean DAR c. 30–20 ka ago (11.4±2.4 cm ka−1) is higher than that c. 20–10 ka ago (3.0±0.1 cm ka−1) in L1–1. The subsequent calculation of the mass accumulation rate (MAR) indicates that the MAR of L1–1 (107 g m−2 a−1) is much lower than those of L1–2 (247 g m−2 a−1) and L1–3 (307 g m−2 a−1). By comparing the mean DAR results during the Last Glacial at Weinan with those at a further six sites from other studies, we observed that the mean DAR of L1–2 is higher (lower) than that of L1–1 on the eastern (western) CLP, and that the mean DAR during MIS 2 has an evident transition from high to low at c. 20 ka on the entire CLP. Possible mechanisms for the above mean DAR changes at orbital and sub-orbital time scales are presented.