PROFILES OF DIGITAL ELEVATION MODELS (DEM) CROSSING THE EASTERN MARGIN OF THE TIBETAN PLATEAU AND THEIR CONSTRAINTS ON DISSECTION DEPTHS AND INCISION RATES OF LATE CENOZOIC RIVERS
青藏高原东缘数字高程剖面及其对晚新生代河流 下切深度和下切速率的约束*

Based on Digital Elevation Model(DEM) analysis,the large-scaled geomorphology of eastern margin of the Tibetan Plateau can be divided into four zones,the Tibetan Plateau,the Longmen Mountain,the Chengdu Basin,and the Uplift Zone of Eastern Sichuan Basin.we used DEM to reconstruct the profiles of maximum,minimum,and mean elevations from the Tibetan Plateau to Eastern Sichuan Basin,and calculated the depth of dissection across the eastern margin of Tibetan Plateau.The river incision rate is calculated as 1.29mm/a,based on the depth of dissection and the age(3.6MaB.P.) of the oldest Minjiang fan deposit in Chengdu Basin.Based on these data,we established the Late Cenozoic coupling relationship between incision rate and surface uplift rate,and found out that the incision rate is four times more than the surface uplift rate.As the incision rate and surface uplift rate in Longmen Mountain are much higher than those in the Tibetan Plateau,we inferred that the Longmen Mountain was the result from the combination of erosion uplift and tectonic uplift.