NEW TECTONIC MOVEMENT IN THE TRANSITIONAL BELT OF PLAINS AND MOUNTAINS IN BEIJING
Li Rongquan Zheng Liangmei Liu Jingzhong (Department of Geography, Beijing Normal University, 100875, Beijing)
The piedmont alluvial fans widespread on the east side of Xishan and the south side of Beishan. According to the plane assemblage relationship of alluvial fans which occurred in different periods at the same place and the classification of plane projection assemblage relationship of fans tops, the piedmont alluvial fans between the Yongding River and Guangou are more typical, especially the one from the Beian River to the Xishan Farm, which appear as a string of beads being inland from the view of plane assemblage and represent the advancing type through the plane projection assemblage. The rates of relative uplift estimated by the fan's top uplift are 20.6mm/a from 1.3×10~4 aB.P. to 8.4×10~3 aB.P., 1.8 mm/a from 8.4×10~3 aB. P. to 4.0×10~3aB.P., and 2.3 mm/a since 4.0×10~3 aB. P.. Apart from the rate of 1.8 mm/a, the others are quicker than that of adjacent places, indicating that this region is unusually uplifting area.