关键词: 丹霞, 彩色丘陵, 地质构造, 成因, 特征, 祁连山

Abstract: This paper introduces the process of development and variation of geologic structure of the Qilian Mountains orogenic belt from the Prepaleozoic era to the Paleozoic era，finally to the Mesozoic era，using practical research results and available research achievements，and based on analyzing the physical geographic condition of danxia landform and colorful hills，geologic structure and distribution characteristics.  From the analyzing the depositional environment，stratum，lithological characteristics，regional structure pattern and forming time，it is believed that the stratum was formed about 100-140 Ma BP，which is during the early cretaceous period. The stratum of total thickness of 5 000 m belongs to river-lacustrine facies red and motley lamellar clastic rock deposition. It is clearly claimed that with the uplift of the Qinghai-Tibet Plateau，rudiment of danxia and colorful hills was nearly formed during 6-7 Ma BP of Pliocene，completely formed during 0.2-0.4 Ma BP of middle Pleistocene.  Besides，according to the internal and external forces of forming the Danxia and colorful hills，the micro analyses were carried out to explore the formation mechanism and appearance features of Danxia landform in the periods of its infancy，middle age，old age and die out age. What’s more，the paper explains the reasons for the sediments forming motley stratum，which is related with the content of Fe3+/Fe2+ and the degree of redox reaction at that time. It is thought that the main color of the stratum is purplish red or brick-red if the stratum has large content of Fe3+ and high ratio of Fe3+/Fe2+，the main color of the stratum is white and black if the stratum has large content of Fe2+ and lower ratio of Fe3+/Fe2+. Furthermore，the article analyses the similarities and differences between Zhangye danxia landform and other danxia landform in southern China，including the depositional environment，geologic structure，stratum lithology and ages and types of stratum and so on. It is believed that Zhangye danxia is an unusual one because it not only has common features of Guangdong danxia landform，which is like the cliffs，but also has common characteristics to Five-color Town in Xinjiang，China，which is colorful. The Zhanye danxia has strong typicality and aesthetic，scientific investigation and ornamental values，which is one of the best seven beautiful danxias in China.

Key words: danxia landform, colorful hills, geologic structure, origins, features, the Qilian Mountains