Long‐term (million year time scale) fault‐slip history is crucial for understanding the processes and mechanisms of mountain building in active orogens. Such information remains elusive in the Longmen Shan, the eastern Tibetan Plateau margin affected by the devastating 2008 Wenchuan earthquake. While this event drew attention to fault deformation on the foreland side (the Yingxiu‐Beichuan fault), little is known about the deformation history of the hinterland Wenchuan‐Maoxian fault. To address this gap, thermochronological data were obtained from two vertical transects from the Xuelongbao massif, located in the hanging wall of the Wenchuan‐Maoxian fault. The data record late Miocene rapid cooling and rock exhumation at a rate of 0.9–1.2 km/m.y. from ~13 Ma to present. The exhumation rate is significantly higher than that in the footwall (~0.3–0.5 km/m.y.), indicating a differential exhumation of ~0.6 km/m.y. across the fault. This differential exhumation provides the first and minimum constraint on the long‐term throw rate (~0.6 km/m.y) of the Wenchuan‐Maoxian fault since the late Miocene. This new result implies continuous crustal shortening along the hinterland fault of Longmen Shan, even though it has not been ruptured by major historic earthquakes. Our study lends support to geodynamic models that highlight crustal shortening as dominating deformation along the eastern Tibetan Plateau.

As the eastern boundary of the Tibetan Plateau, Longmen Shan possesses a narrow thrust belt with steep topography but lacks matching Cenozoic foreland basin. Multiple kinetic models have been proposed to debate on the dominant mechanism of developing such range–foreland system. Crustal shortening rate is a feasible approach to test different tectonic models and estimate structural patterns. In this study, we focused on the deformation pattern and shortening rate of the complex foreland area of the southern Longmen Shan, which is comprised of the Xiongpo, Sansuchang, and Longquanshan anticlines. By the means of net-based RTK measurement and Quaternary chronology, we measured and dated the six-level terraces of the Qingyi River, which flows southeastward across this region. Excess area method was applied to calculate shortening rate. The results indicate that the Late Quaternary shortening rates of the Xiongpo anticline, Longquanshan anticline, and Sansuchang anticline are 1.01 mm/yr, 0.89 mm/yr, and 0.16 mm/yr, respectively. The total shortening rate of the foreland in southern Longmen Shan is 2.06 mm/yr. Consequently, a mechanical model was presented to show the tectonic pattern: the southern Longmen Shan is an actively expanding edge of the plateau, and the shortening is distributed to the three anticlines dominated by the foreland detachment system. This model supports that crustal shortening is the dominating force in the current orogenesis of the Longmen Shan. In addition, the along-strike variation of the Longmen Shan was further specified from the perspective of crustal shortening distribution. We propose that the southern Longmen Shan and its foreland basin are in a state of compression, while the northern Longmen Shan has both thrust and strike-slip characteristics.

The Lijiang–Jinpingshan fault (LJF) is an important secondary boundary fault that obliquely cuts the Sichuan–Yunnan rhombic block. It is of great significance for understanding the tectonic evolution of the Sichuan–Yunnan rhombic block and even the southeastern margin of the Tibet Plateau. Based on a digital elevation model (DEM), this work combines ArcGIS with MATLAB script programs to extract geomorphic indices including slope, the relief degree of the land surface (RDLS), hypsometric integral (HI), and channel steepness index (k_sn) of 593 sub–watersheds and strip terrain profiles around the LJF. By analyzing the spatial distribution characteristics of the geomorphic indices and combining the regional lithology and precipitation conditions, the spatial distribution of the geomorphic indices around the study area was analyzed to reveal the implications of the LJF’s activity. The results of this work indicate that (1) the distribution of geomorphic indices around the LJF may not be controlled by climate and lithological conditions, and the LJF is the dominant factor controlling the geomorphic evolution of the region. (2) The spatial distribution patterns of geomorphic indices and strip terrain profiles reveal that the vertical movement of the LJF resulted in a pronounced uplift on its northwest side, with tectonic activity gradually diminishing from northeast to southwest. Furthermore, based on the spatial distribution characteristics of these geomorphic indices, the activity intensity of the LJF can be categorized into four distinct segments: Jianchuan–Lijiang, Lijiang–Ninglang, Ninglang–Muli, and Muli–Shimian. (3) The activity of the LJF obtained from tectonic geomorphology is consistent with the conclusions obtained in previous geological and geodesic studies. This work provides evidence of the activity and segmentation of the LJF in tectonic geomorphology. The results provide insight for the discussion of tectonic deformation and earthquake disaster mechanisms in the southeastern margin of the Tibet Plateau.

River terraces and alluvial fans preserve important records of landscape evolution, yet establishing their relative chronology is often difficult where suitable materials for numerical dating are scarce. This study explores whether geomorphic-surface roughness and sediment chemical weathering can be used together to reconstruct the long-term evolution of fluvial surfaces across extended Quaternary timescales in the Qingyi River basin on the eastern margin of the Tibetan Plateau. We combine digital-elevation-model-based roughness analysis with major-element geochemistry and previously established age constraints for a sequence of river terraces and paleo-alluvial fans developed under humid and strongly erosive conditions. The results show that younger surfaces generally retain smoother depositional morphologies, whereas older surfaces display greater topographic variability caused by progressive runoff erosion, gully incision, and surface fragmentation. At the same time, older deposits record stronger chemical alteration, expressed by increasing depletion of mobile elements and enrichment of relatively immobile components. When evaluated against surface age, both roughness and the Chemical Index of Alteration follow nonlinear, progressively saturating trajectories. These trends indicate rapid geomorphic and geochemical modification during the early stages of exposure, followed by a gradual decline in the rate of change as weatherable minerals are depleted and landscape dissection approaches an advanced state. Neither proxy shows a simple correspondence with glacial–interglacial cycles. Instead, their long-term age-dependent trends reflect the cumulative effects of physical erosion and chemical weathering acting over the duration of surface exposure, while climate modulates the rates and relative intensities of these processes. The parallel evolution of roughness and weathering therefore provides complementary evidence for surface age and preservation. When evaluated against independently constrained surface ages, their joint use provides complementary evidence for the relative correlation of terraces and alluvial fans, especially in humid mountain-front settings where suitable materials for numerical dating are limited.