Luminescence dating and the sedimentary pattern of loess on the Tibetan Plateau

Aeolian sediments in the Tibetan Plateau are important records for climate change and atmospheric circulation. Previous studies suggested that the interior Tibetan loess accumulated mostly in the Holocene (<11.7 ka) marked by warming and wetting climate with an increased vegetation cover, thereby facilitating dust entrapment, and that this Tibetan dust accumulation model is different from that of the Chinese Loess Plateau (CLP). In longer time scales (>11.7 ka), did Tibetan loess deposited in warm/wet period as well? To answer this question, we presented 23 loess luminescence ages from five aeolian deposit profiles in the central Tibetan Plateau covering a large area. The results demonstrate loess deposition at around 30 ka and 75 ka, corresponding to warm and wet marine isotope stage (MIS) 3 and 5. In contrast, in the MIS 2 and 4, little to no loess was detected. Thus, we conclude that Tibetan loess accumulated mainly during warm/wet periods in the orbital time scale, and vegetation cover played a key role on loess accumulation and subsequent ecological system. This study sheds light on the Tibetan Plateau dust and loess research, and further provides basic scientific data for comprehensive understanding of the TP ecosystem for sustainable development.