Preliminary Digital Geomorphologic Research on Southeastern Margin of Qilian Mountains Based on RGMAP

The typical stratified landforms in the southeastern margin of the Qilian Mountains have been recognized and studied in detail on the basis of digital elevation model, field survey and tectonic- geomorphologic section as well as the indoor study with the support of the operation system of regional digital geological survey and field mapping (RGMAP). There are two stages of planation surfaces (P I 3 000 m, P II 4 000 m), eleven stages of pediments (Pe 1-11) and seven terraces (T 0-T 6) of the Huangshui River. Five terraces are developed in the Yellow River from the Yanguoxia to Bapanxia. Before the Yellow River mainstream passed through the Yanguoxia about 0.15 Ma, the Huangshui River used to be its upper reach. Combined with field survey and analyses indoors, every stages of stratified landforms (planation surfaces, pediments and terraces) are recognized, showing detailed features of distribution, sedimentary and formation ages and relation with neo-tectonic movements. This demonstrates that development of typical stratified landforms resulted from phased uplift of the Qinghai-Xizang plateau in Late Cenozoic.