Chronology and dust mass accumulation history of the Wenchuan loess on eastern Tibetan Plateau since the last glacial

Abstract

Loess deposits are spread widely over the eastern Tibetan Plateau (ETP), and constitute key terrestrial archives for reconstructing the paleoenvironments of the late Quaternary, which are still poorly understood. This study creates a detailed chronology of the Wenchuan loess sequence in the ETP through the quartz optically stimulated luminescence dating and radiocarbon dating. The results show that loess has accumulated in the area since at least ∼57.7 ka. We show that the variation in the history of the mass accumulation rate (MAR) spanned 4.8–108.0 g cm−2 ka−1, with a mean value of 43.9 g cm−2 ka−1 since the last glacial. The MAR of MIS 3 was the highest over the last glacial, with two peaks at 48–44 ka and 35–32 ka; whereas the MAR of MIS 2 was slightly lower and its peak appears at 21–18 ka. The MAR during the Holocene was generally low. Moreover, four enhanced dust events were superimposed on changes in the long-term MAR and correlated with the corresponding Heinrich events. The variation in the MAR of Wenchuan loess since the last glacial period has been similar to that in the eastern Chinese Loess Plateau (CLP) but differing from those of the western CLP. Our results reveal the spatial difference of MAR since last glacial, and can contribute to a better understanding of the link between the evolution of dust deposition and environmental changes in the ETP.