DEM-based Tectonic Geomorphology Study In The Northeastern Margin Of Tibetan Plateau

As Tibetan Plateau is affected by tectonic activity and climate, many geomorphologic units emerge, such as rugged summits which are formed by obduction, extensive basins with high altitude and low relief, as well as basin-range system made up of linear range and intermountain basin. Geologists both in and abroad pay a great attention to studies on kinematics, dynamic mechanism, uplift process and tectonic deformation of Tibetan Plateau.In recent years, researches on plateau uplift and orogenic evolvement focused on the evidence of surface process. All the studies have been becoming semi-quantitative and quantitative. And the key target of these studies is the carrier, i.e. landform, which recorded the crustal deformation and climate changes during geological time. Digital Elevation Model is a digital description of land surface, which can provide new means and perspective on study of geomorphology.In this paper we discuss the large-scale geomorphologic characteristics of northeastern Tibetan Plateau based on numerical analysis of a digital elevation model obtained from STRM DEM, whose special resolution is 90m. By choosing different morphometric parameters we generate within ARCGIS 9.2 a series of maps reflecting the features of study area, such as the summit level map, mean elevation map, base level map, average slope map and local relief map. From the maps above, we find that the study area characterizes low average slope and low relief with a step shape. Comparing the morphometric parameters shows a linear relationship between average slope and local relief, both of which can reflect roughness of land surface. Moreover, average slope and local relief initially increasing with elevation at lower altitude can be explained by river incision, and that at higher altitude is caused by the action of ice and mechanical weathering. Finally, we conclude that the factors controlling the geomorphic characteristic of low relief in our study area is rock types, sedimentation, weathering and high-altitude peneplanation.