延安地区丹霞地貌是国内外地貌学界近年来的最新发现和持续关注点。通过对延安地区丹霞地貌地质遗迹的系统调查和研究发现,该区丹霞地貌景观资源丰富,类型多样,具有较高的观赏价值和科学研究价值。通过野外考察和岩石样品分析,从地质构造、地层组合、岩性特征和外动力等方面来探讨延安地区丹霞地貌的发育机制。研究表明：晚白垩世以来,该地区经历多次构造抬升和新生代以来地壳保持差异升降,区内构造简单,地层产状平缓,但节理、裂隙数量较多,对延安地区丹霞地貌的发育具有控制作用;延安地区丹霞地貌造景岩层主要为白垩系志丹群洛河组（K₁l）,为一套干旱气候条件下的红色碎屑岩沉积,沉积环境为沙漠环境,岩层倾角近于水平,为丹霞地貌的发育提供了较好的物质基础;岩性特征上,延安地区丹霞地貌造景岩层岩石成熟度不高,硬度低易碎,抗侵蚀能力较弱,岩石具有相似的矿物组成及峰值强度分布,其沉积过程经历了较为复杂的风力作用过程,岩石强度存在差异性,易受到后期外动力作用的改造;外动力方面,季节性的流水是塑造“沟谷型”丹霞地貌的主要外动力,此外,凹片状和凸片状风化作用以及崩塌作用对延安丹霞地貌的发育也有重要影响。

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.