Abstract:

The Danxia landform in Yan’an City, Shannxi Province, China is a new finding and continuous concern in the geomorphology field at home and abroad. By investigating and researching the Danxia landform geoheritage resources in Yan’an, we found that Danxia landform resources are rich and varied, with high ornamental and scientific research value. Based on the field investigation and analysis of rock samples, this study examines the developmental mechanism of Danxia landforms in Yan’an from geological setting, stratigraphic assemblage, lithological features, and exogenic forces viewpoints. Research shows that since the Late Cretaceous, the area experienced many structural uplifts and the crust differentially rose and fell since the Cenozoic. The structure in the area was simple, and the stratum gentle, but the number of joints and fractures was large, controlling the development of the Danxia landform in Yan’an. Landscape formation of the Danxia landform in Yan’an is predominantly the Luohe Formation (K₁l) of the Cretaceous Zhidan Group (a set of red clastic rock deposits in arid climatic conditions) and desert environment. The rock stratum inclination is almost horizontal, providing a good material basis for developing the Danxia landform. From lithological characteristics, the Danxia landform rock formation in Yan’an has low maturity, low hardness and fragility, and weak erosion resistance. The rocks have similar mineral compositions and peak strength distributions. Its sedimentary process experienced a more complex wind action process, and the rock strength is different, which can be easily modified by later external dynamic action. Finally, regarding external power, seasonal water is the principal external power shaping the valley-type Danxia landform. Furthermore, the concave and convex weathering and collapse significantly influence the development of the Danxia landform in Yan’an.

Key words: Danxia landform, type, developmental mechanism, Yan’an area