Climate factors, including precipitation and related vegetation cover, which are vital features of monsoon climates, differ across global/regional areas and are highly variable on a catchment scale. The correlation between fluvial processes and the phases of monsoon climate change are poorly understood in the north-eastern Tibetan Plateau (NETP), partially because direct monsoon climatic proxies from fluvial sediment are lacking. In this study, we compared the fluvial activity with monsoon climate changes reconstructed from pollen analysis, optically stimulated luminescence (OSL) dating, and sedimentary features of terrace sediments in the Datong catchment. The results show that pollen from upstream, for example, 20–30 km from the sample site and transported by water flow, makes the greatest contribution to the pollen assemblages of overbank sediments, which provides reliable regional climatic information. The overbank sediments of the fourth terrace (T4) are dated to around 57.1 ka; beneath these, the lower braided-river gravel was likely deposited during the early part of the Marine Isotope Stage (MIS) 4. The pollen-inferred vegetation is forest-steppe, reflecting a strong monsoon under warm and wet climate conditions during the deposition in the middle sediment unit, possibly during MIS 3. Afterwards, alluvium aggradation ended, and pronounced incision and abandonment was observed in the terrace surface followed by loess deposition which likely occurred during MIS 3–2, at the initiation of the decline of the monsoon. The basal sediment unit of the second terrace (T2) was dated to approximately 6.5–5.0 ka, indicating the start of alluvial aggradation during the Holocene Optimum. Relatively high arboreal pollen from the basal sediment unit of T2 shows a relatively strong monsoon with a warm and wet climate. This was followed by the deposition of the middle sediment unit when the climate was relatively drier with a weak monsoon, recorded by herbaceous vegetation dominated by Artemisia and Chenopodiaceae. It was deduced that during the following cold–warm transition, the river could incise deeply, and this terrace was formed under increasing monsoon conditions. The deep incision and formation of the two studied terraces correlate with different phases of climate change: a warm-to-cold climate transition (decreasing monsoon) for T4 and a cold-to-warm climate transition (increasing monsoon) for T2. We argue that the extreme climatic events at millennial–centennial scales during the Holocene, in addition to orbital-scale changes of monsoon variation, might have led to fluvial thresholds being crossed, causing intense incision and terrace formation. However, the correlation of fluvial processes in the NETP as a response to the East Asian monsoon at different temporal scales could be highly variable.

气候因素，包括降水和相关的植被覆盖，是季风气候的重要特征，在全球/区域范围内有所不同，并且在集水区范围内变化很大。在青藏高原东北部（NETP），人们对河流过程与季风气候变化阶段之间的相关性了解甚少，部分原因是缺乏来自河流沉积物的直接季风气候代理。在这项研究中，我们将河流活动与通过花粉分析重建的季风气候变化，光激发发光（OSL）年代以及大同流域阶地沉积物的沉积特征进行了比较。结果表明，花粉是从上游（例如距采样点20–30 km）通过水流运输的，对过剩沉积物的花粉组合做出了最大贡献，从而提供了可靠的区域气候信息。第四阶地（T4）的岸上沉积物的年代约为57.1 ka。在它们之下，下部辫状河砾石可能是在海洋同位素阶段（MIS）4的早期沉积的。花粉推断的植被是森林草原，反映了在沉积期间温暖湿润的气候下的强烈季风。中间沉积物单元，可能是在MIS 3期间。随后，冲积层结束，并在梯田表面观察到明显的切口和遗弃，随后在季风下降开始时在MIS 3–2期间发生了黄土沉积。第二阶地（T2）的基础沉积物单元的日期约为6.5–5.0 ka，表明在全新世最佳时期开始了冲积作用。来自T2基底沉积物单元的相对较高的树木花粉表现出相对较强的季风和温暖湿润的气候。其次是中部沉积物单元的沉积，当时气候相对较干燥，季风较弱，记录以草本植物为主。蒿和藜科。据推论，在随后的冷暖过渡过程中，河流可能会深切，而这个阶地是在季风条件不断增加的情况下形成的。两个研究阶地的深切和形成与气候变化的不同阶段相关：T4的从暖到冷的气候转变（季风减少）和T2的从冷到暖的气候转变（季风增加）。我们认为，全新世期间千禧年至百年尺度的极端气候事件，除了季风变化的轨道尺度变化之外，还可能导致越过河流阈值，导致强烈的切口和阶地形成。但是，NETP中河流过程对东亚季风在不同时间尺度上的响应的相关性可能是高度可变的。