Abstract:

 This paper characterized the weathering crust and planation surface in Zhangjiajie based on the field investigation, geochemical analysis, and regional comparison. It is indicated that the planation surface formed in humid environment of Late Tertiary Period, followed by the occurrence of erosional surface. Structures of weathering crusts from the planation surface are clear, showing artificial soil, residual layer, semiweathered rock and rock downward. The weathering crust is dominated by high silicon and low aluminum, suggesting the moist and hot environment. On the regional scale, the planation surface in Zhangjiajie at the altitude of 1,100-1,300 m occurred in humid environment of Late Tertiary Period, whilst the lower erosional surface （800-950 m） appeared between the Late Pliocene and Early Pleistocene.

Key words: planation surface, weathering crust, formation environment, Zhangjiajie