对黄土高原风尘搬运动力与沉积控制因素的新认识

风尘是地球表层系统的重要组成部分，广泛参与地球系统中不同时空尺度的物理、化学和生物过程，对全球气候和生态环境产生重要的影响。中国北方地区发育了世界最广、最厚的风尘沉积，记录了至少22 Ma以来东亚季风演化和亚洲内陆干旱化历史。半个多世纪以来对风尘沉积的气候记录和黄土高原的成因进行了大量研究并取得了丰硕成果，然而对黄土高原风尘物质沉积过程的认识还存在很多问题。例如，近年来基于物源示踪研究对传统的风尘搬运过程提出了新认识，认为虽然黄土主体是风成的，但以前忽略了河流对于碎屑物质的搬运贡献。我们在前人研究基础上从沉积学角度分析风尘沉积过程，发现青藏高原两期抬升与区域构造运动对粉尘沉积起着不亚于气候变化的重要控制作用；同时从沉积-侵蚀和地貌发育过程探讨风力与流水这两种最常见的外动力方式在黄土沉积和黄土高原发育过程中所起的作用，认为风尘的沉积和黄土高原的形成是侵蚀与搬运沉积作用的长期动态平衡过程，风力和流水在其中所起的作用都不是单一不变的，在不同时期和不同区域有可能会同时充当建设者和破坏者的角色。

New Research Progress of the Transport Dynamics and the Accumulation Factor of the Aeolian Dust in Chinese Loess Plateau

The aeolian dust is an integral component of the Earth surface system dynamics, participating in a range of physical, chemical and biogeological processes of the Earth system at various temporal and spatial scales. Especially, in the central Asia formed the large arid and semiarid areas, which is main source for the aeolian dust. The Asian dust cycle is one of the major dust systems on Earth, playing important roles in many processes and exerting impacts well beyond the region but the global scale. The thick aeolian dust deposits in the Chinese Loess Plateau (CLP) are considered to provide the best terrestrial record for the onset of Asian interior aridification and the evolutionary history of the Asian Monsoon. After more than 50 years' hard work in the CLP, brilliant achievements about the aeolian dust have been gotten not only through the geolical records but also the numerical modeling. However, large variability in the basal ages of aeolian deposits makes the aeolian dust depositional history and the controlling dynamics controversial. The large aeolian dust accumulation is the result of joint efforts by both sides of tectonic activities and the climate changes.The previous research focused on the climate changes much but it seem to fail to take into accout the fact that tectonics also play a key role in the process of produce and transport the aeolian dust, which is named "Dust Factory". Here we present a preliminary hypothesis for the tectonic controls of aeolian dust deposition in the CLP by connecting the two main uplift events of the Tibetan Plateau and the regional tectonic events with the aeolian dust accumulation history. Regional tectonic events in the Ordos Block (the basement of the CLP) during the Late Cenozoic are less recognized as controlling aeolian dust accumulation by sculpting the surface landscape. The stable tectonic environment of the Ordos Block since the Late Miocene might have been the main controlling factor that enabled the wide deposition of the aeolian Red Clay after~8 Ma. At last but not least, the previous research have redefined the roles of the rivers and wind in the formation of CLP. Though the loess has an aeolian origin, the rivers also takes important part in transporting the detrital material as a near source for the aeolian dust. We demonstrate that the accumulation and preservation of aeolian deposits within the CLP is actually largely controlled by the regional tectonic environment, climatic factors and the results between accumulation and erosion.