Fluvial landscapes are a result of lithospheric tectonic movement, climate evolution and surface processes. Existing evidence proves that regional tectonic deformation can be reflected by the evolution of fluvial landforms. The southern Alashan Block lies the closest to the northeastern Tibetan Plateau and has become the latest plateau outward expansion boundary. Yabrai Shan is located at the intersection of the Tibetan Plateau, Alashan and Ordos Blocks, thereby recording the evolution of the surface processes and tectonic activities in the northeastern Tibetan Plateau and its surrounding regions. Herein, we conducted the quantitative landform analysis and field investigations of Yabrai Shan, and the spatiotemporal distribution of geomorphological parameters indicated that Yabrai Shan is in the mature stage of geomorphological evolution controlled by tectonic activities of the Yabrai range-front fault. Based on the paleochannel reconstruction model and previous research on fault activity, two tectonic acceleration events were identified, with estimated geomorphic response times of 0.15–1.10 Ma and 1.42–2.92 Ma. Different distribution characteristics of two-phase knickpoints are caused by the change of tectonic stress in this region, revealing that the late knickpoints are the result of tectonic acceleration under the influence of the northeast expansion of the Tibetan Plateau. The transformation of Yabrai Shan from the original extensional environment affected by the Ordos Block to the compressional environment affected by the northeast expansion of the Tibetan Plateau occurred after 1.10 Ma.
The Longshou Shan, located in western China, plays a crucial role in connecting the Tarim Continent with the North China Craton. It provides valuable insights into the Cenozoic intracontinental deformation, the complex dynamics of Eurasian tectonics, and the relationship between the pre-Cenozoic Tethys and Central Asian orogenic systems. Consequently, comprehending the evolution of the Phanerozoic era in this region holds immense significance. Zircon (U-Th)/He (ZHe) dating was conducted on three granite samples (n = 18) collected from the Longshou Shan. The ZHe dates of these granite rocks range from 7.2 to 517.7 Ma, showing a negative correlation with eU values. Furthermore, a limestone sample from the Longshou Shan yielded ZHe (n = 4) ages of 172.0–277.1 Ma and AHe (n = 4) ages of 17–111.9 Ma. The area has undergone complex tectonic processes involving multiple phases of uplift and burial. Using both forward and inverse modeling methods, we aim to establish plausible thermal histories. Our models reveal: (1) Late Paleozoic unroofing; (2) Early Mesozoic cooling and Late Mesozoic regional stabilization; and (3) Cenozoic reheating and subsequent cooling. By investigating the intricate thermal history of the Longshou Shan through multi-method modeling, we compare different approaches and assess the capabilities of single ZHe dating for understanding a thermal history. This research contributes to unraveling the region’s geological complexities and aids in evaluating various modeling methods.