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The eastern Qilian Shan is a tectonically-active region consisting of a series of faults with bounded intermountain basins and is located within the transition zone between the mainland Tibetan Plateau and the Alax Block. Active deformation affecting the topography in this region can be quantified based on geomorphic indices. Therefore, we applied the geomorphic indices (hypsometry and stream-power incision model) to evaluate the tectonic deformation pattern of the eastern Qilian Shan. Hypsometric curves and S-A plots of the selected seven rivers were determined. HI values of every single sub-basins were also calculated. The results show that the local topographic evolution of the eastern Qilian Shan is in pre-steady state and will soon reach its equilibrium state. According to the analysis of regional climate condition (e.g., rainfall and glaciers distribution) and fault characteristics, it is suggested that abundant glacial snowmelt water sustains fluvial incision, and tectonic deformation from sustained northeastward expansion of the Tibetan Plateau is the main reason for the landscape growth. Combining the research of the deep electric structure beneath the Gulang Boundary Zone, we claimed that the eastern Qilian Shan (even the northeastern Tibet) has been growing and expanding northeastward since the middle Miocene, and its leading edge now is the Hexibao-Sidaoshan Fault. On the premise of synthetically considering the western and middle parts of the Qilian Shan, it is suggested that the Hexibao-Sidaoshan Fault area will rise into a mountain in 1–2 Ma.

Cenozoic basins and ranges constitute the high topography of the northeastern Tibetan Plateau which is derived from the Indo-Asian collision. The geomorphological characteristics of the ranges provide direct insight into the uplift processes which are responsible for the patterns of the ranges and the growth of the northeastern Tibetan Plateau. This study analyzed the geomorphological features of Qinghai Nanshan (one of the youngest ranges within the northeastern Tibetan Plateau), including elevation, slope distribution and the channel steepness index. Topographic analysis revealed that elevations and slopes in western and central portions of Qinghai Nanshan were higher than those in the eastern portion, whereas the channel steepness index revealed a step-growth mode from west to east. Considering the topographic features, the lateral gradient of precipitation (increasing from west to east) and the lithology distribution, it is concluded that the geomorphological features of Qinghai Nanshan are influenced mainly by tectonic activities and reflect the growth pattern and/or the tectonic setting of the range. Comparing with previous studies, it is shown that the formation mechanism of Qinghai Nanshan follows a middle-to-sides growth pattern. Furthermore, the degree of inclination of the erosion surface distributed on the northern flank of the range suggests that Qinghai Nanshan is controlled jointly by the listric Qinghai Nanshan thrust fault and the influences from the Elashan and Riyueshan dextral strike slip faults. In addition, the northeastern Tibetan Plateau exhibits an outside-in growth process, which might reflect the northeastward growth of the entire northeastern Tibetan Plateau.

Based on field mapping, section measurement and magnetostratigraphy, ∼1700 m of sedimentary rocks have accumulated in the Wushan basin between ∼16 Ma and ∼6 Ma. Basin geometry, sedimentation characteristics and the early syn-depositional deformation along the northern margin of the basin indicate that formation of the Wushan basin was related to tectonic deformation along the West Qinling fault zone during the middle Miocene. A series of basins of similar age to the Wushan basin were generated along and to the south of the West Qinling fault zone while basalts also erupted in this region at this time. We suggest that the middle Miocene (∼16 Ma) may represent a change in kinematics and deformation style in the region along and to the south of the West Qinling fault zone. At this time, there was a transition from NNE–SSW compressional deformation, that dominated the region since the late Paleogene, to the development of WNW–ESE and/or E–W trending strike-slip movement and associated transpressional and transtensional activity that continues today. The Miocene Wushan basin may have developed in association with transpression along the West Qinling fault zone. Whether this transition was related to the onset of strike-slip along the east Kunlun fault and related deformation transfer, lower crustal flow, or removal of mantle lithosphere, the middle Miocene provides direct evidence for a change in the kinematic style along the plateau margin.