A Study On The Structure Features And Its Relationship With The Danxia Landforms In Kongtong Mountain

Danxia landform belongs to the landforms with red clastic rock and steep cliffs,which has high landscape value and scientific research value.The Danxia Landform of Kongtong Mountain has unique characteristic and great research value because of its special structure location,where is in the transition zone between the Ordos Basin and the Liupanshan Orogenic Belt.However,the current research on the formation mechanism of the Danxia landform is not enough,and the combination with mature theories and the research methods in this direction are also relatively single.Therefore,through the combination of mature theoretic disciplines and the introduction of quantitative research methods,this paper studies the tectonic characteristics of Danxia landforms of Kongtong Mountain and discussed their relationship with the evolution of Danxia landforms,and Further study on the formation and evolution of the Danxia landform,and enrich the research system of Danxia landform.Based on the topography and geomorphology,stratigraphic lithology,regional tectonic and geological evolution of the area of Kongtong Mountain,this paper conducted field geological surveys on the piedmont faults and joint characteristics,and reveals new tectonic movements.By measureing the river terraces of Liushugou and Houzhigou,discovering stable five-stage terraces in the Jinghe.Then,revealing the crustal uplift law in this area by refereing literature to determine the age of the terraces.Using Geographic Information System(GIS),this paper extracted linear structure,water system density,and tectono-geomorphological features within the study area to study the characteristics of the Neotectonics in the Kongtong Mountain.Combining the regional geological environment with the characteristics of neotectonic movements,the relationship between the structural features with Danxia landforms of Kongtong Mountain was analyzed: the piedmont fault controlled the stratum and landforms of the region;the differences and stages of the tectonic movement determined the structure of the Danxia landform;tectonic fractures,including linear structures and joints,cutting and shaping Danxia landform.The main conclusions are as follows:(1)The piedmont fault has had strong tectonism and controlled the development of river terraces,landforms,and stratum types on both sides of its east and west.The Mesozoic red beds were developed on the Kongtong Mountain in hanging wall of fault,lifted under the tectonic movement and were strongly weathered.Therefore,Kongtong Mountain has accumulated less Cenozoic strata and developed into a large and steep Danxia landform.(2)In the study area,the Jinghe has developed stable grade five terraces.The T5,T4,and T3 have been affected by the Kunlun-Yellow River movement and constantly eroded both sides of the valley.The T2 and T1 are corresponding to the Gonghe movement,and the tectonic uplift is strong.In addition,the time for the formation of the T5 is the same as the 3th planation surface,indicating that the region has experienced at least seven intermittent tectonic uplifts-flattening and erosing,resulting in differentiatiating and shaping the Danxia landform.(3)By using the spatial analysis function of Arcgis,extracting tectonic geomorphologic parameters.The results showed that HI,surface roughness,and surface depth of cut in the Shiwandaxiagu,Xiangshan,Huangcheng and Houxia were larger,and the structural activity was higher than elsewhere.The parameters to be extracted were combined with the Danxia landforms of Kongtong Mountain.It was found that the HI ranged from 0.35 to 0.6,which developed a large number of Danxia landforms.It shows that geomorphological erosion and tectonic activity are in a state of equilibrium,which is typical of the topography of the mature stage.In addition,the most Danxia landforms developed in the surface cutting depth range of 21.51 to 32.04 and in the surface roughness range of 1.19 to 1.3.It revealed that there were a lot of Danxia landforms in areas with large topographic relief,strata erosion and strong tectonic activity,and tectonic movement had a strong control over the development of Danxia landforms.(4)In addition,linear structures and joints would further shape the Danxia landform.Under the linear structure cutting action of NE and E-W dominant directions,the Danxia landform of Kongtong Mountain was cut into the shape of Fangshan,butte,cliff,tableland,and gully.The research area mainly developed N-S direction of the joints,and some areas developed NE direction.Under the dominant joints cutting,water erosion,and gravity collapse,the Danxia cliffs continued to recede,the rushing gully developed into one-line-sky landscape,and Danxia caves produced along vertical joints.