| Due to the collision between the Indian Plate and the Eurasian Plate,the Tibetan Plateau has exhibited strong uplift since the Late Cenozoic.Qianhe River,located at the intersection of the Northeastern Tibetan Plateau,the Qinling orogenic belt,and the Southwestern Ordos Basin,controlled by the Longxian-Baoji fault zone,has been confirmed as the forefront of the northeastern lateral expansion of the Tibetan Plateau.It contains rich information about new tectonic movements and studying its Cenozoic tectonic geomorphology helps to gain a deeper understanding of the dynamic relationship between the tectonic transition block and the above three tectonic units.Thermochronology and river terraces indicate that the Qianhe River basin and its adjacent areas experienced two rapid cooling events at ～8 Ma and ～1.4 Ma,respectively.However,thermochronology methods can only obtain the average uplift rate since a certain time,and the process of the change in uplift rate during the Late Miocene to early Pliocene in this area is unknown.The morphology of the bedrock river longitudinal profile records the history of basin tectonic activity,and the analysis of longitudinal channel profiles and hydraulic erosion models provide an effective method to quantitatively constrain the tectonic activity history of the study area,bridging the results of studies at different time scales,such as active tectonics and thermochronology since the Cenozoic.Therefore,this study used tools such as ArcGIS and MATLAB to extract the Qianhe River basin from 30 m resolution ASTER-GDEM data,and revealed the Late Cenozoic uplift history of the Qianhe River basin through analysis of its tectonic geomorphology,river longitudinal profiles,fault genesis identification,and linear inversion.The main results are as follows:(1)two periods of tectonic fault genesis were identified in 14 rivers in the Qianhe River basin,and it was believed that the geomorphic evolution of the region was controlled by tectonic activity,and linear inversion of the uplift history could be carried out;(2)the uplift history of the Qianhe River basin since ～15 Ma was inverted: the uplift rate in the study area increased sharply at ～8Ma and ～1.4 Ma,and the rates in the northwest and southeast increased to ～0.17 mm/yr and～0.15 mm/yr,respectively,since ～1.4 Ma.Overall,the uplift rate in the northwest of the study area was higher than that in the southeast during the same period;(3)the new tectonic activity in the study area is the result of the eastward thrusting of the Tibetan Plateau through the Longxi block and the Qinling orogenic belt,reflecting the feasibility of using river longitudinal profile inversion to reveal the uplift history of the basin-mountain coupling zone. |
