Study on Landscape Characteristics and Development Evolution of Typical Danxia Landforms in Yan'an
In this study,the landscape characteristics of typical Danxia landforms in Yan'an were analyzed using cosmogenic nuclide 10Be and 26Al techniques to obtain exposure ages and erosion rates to investigate the evolutionary history of the"loess-covered valley Danxia"landscape.Our results showed that typical types of Danxia landform in Yan'an include slit type,stone mushroom type,and natural bridge type,and the landscape characteristics of the slit-type Danxia are"narrow,multi curved,rhythmic,and colorful".Moreover,the typical"loess-covered valley Danxia"was categorized as a stone mushroom-type Danxia landform,and was characterized by a unique and beautiful shape.The natural bridge-type Danxia landform is large in overall scale.Both of these landforms are formed by vertical joints and erosion by external forces.Using cosmogenic nuclide 10Be and 26Al techniques,we calculated that the exposure age of Zhidan Maoxiang slit Danxia landscape formed in two stages,(0.75±18)～(0.83±0.14)ka and(1.14±13)～(1.29±0.30)ka.The exposure age of the Wangjiawan mushroom-type Danxia landform in Ansai is(1.76±0.45)～(1.77±0.15)ka.These two Danxia landforms formed in the Holocene(Qh),the former developing after the latter,and the terrain is relatively young.Using cosmogenic nuclide 10Be-26Al techniques,the erosion rate of the two typical Danxia landforms was determined to be(39±3.3)～(104±24.4)cm·ka-1.Compared with the current erosion rate obtained by domestic and foreign scholars studying the surface and bedrock,the erosion rate of these two typical Danxia landforms is relatively high,and the results need further examination.The landscape evolution of Danxia landforms in Yan'an began with the accumulation of red beds during the Cretaceous.The landforms have gone through roughly four evolution stages,initially revealing that geological structure,overlying loess cover,water,and other factors jointly control and affect the formation of typical Danxia landforms in Yan'an,and the evolution stage is generally in the late early stage.
Yan'anlandscape characteristics of typical Danxia landformcosmogenic nuclides 10Be and 26Alexposure ageerosion rateformation and evolution
万方数据
维普
