The relationship between pluvial fan and terrace morphology and differential tectonic movement along the North Qinling fault zone, Shaanxi Province, China

The North Qinling fault zone is the southern boundary of the Weihe basin. The fault zone may be divided into 3 segments by the analysis of the pluvial fans and river terraces developed along the North Qinling piedmont. The inset type of pluvial fans is developed in the middle segment and the buried type of pluvial fans along the eastern and western segments. The different types of pluvial fans along the fault zone show that the activities are quite different in different segments of the fault. The north wall of the middle segment is deeply down-faulted and those of the eastern and western segments were slight subject to subsidence during the Quaternary Period. The characteristics of the vertical fault movement agree well with the results obtained from the analysis of the river terraces. The vertical displacement of river terraces is larger, about 15-26 m for the second terrace in the middle segment, than that of the eastern and western segments: about 6-12 m for the second terraces during the late Pleistocene. The terrace surfaces in the North Qinling Mountains gently dip towards the south. This indicates that the Qinling Mountains have been titling from north to south during the Quaternary Period.