Genesis On The Characteristics And Formation Mechanism Of The Danxia Landform In Zhejiang Province Jiangxi Province And Fujian Province

Development of typical Danxia geomorphologic landscape in Zhejiang,Jiangxi and Fujian mainly experiences geomorphic evolution processes including evolution of Danxia Basin,scenery created by erosion of surface force.Red-bed basin in the southeast of China is gradually formed as Pacific Ocean dives into inland and forms deep fracture,and then experiences orogenesis of Yanshan movement and tension process of geological structure.These basins are material basis and preconditions of forming sedimentation and landscape of Danxia landform.At the same time,a large number of geological materials indicate that volcanic activity plays an important role in forming process of basin.Sedimentary facies belt decides Danxia landform types and joint of fracture decides the trend of valley.Erosion of external force and lithological difference weathering results in formation of Danxia geomorphologic landscape in research area finally.According to causes and characteristics of Danxia landform,the paper found out that by on-site reconnaissance and sampling,uniaxial compressive strength of rock,lithology identification with polarizaing microscope and porosity experiment that lithology of Danxia landform in research area is mainly constituted by three classes:sandstone,conglomerate and igneous rock.Sandstone is mainly medium and fine-grained sandstone and anisometric sandstone;conglomerate is mainly psephitic structure and massive structure,and particle diameter of gravel in conglomerate is different;igneous rock mainly includes volcaniclastic rock,rhyolite and tuff.Volcanic-intrusive rock is relatively more and rock debris of sandstone rock and conglomerate contains more rock debris of igneous rock at the same time.Rock sample presents moderate-bad roundness and poor sorting features.Interstitial material mainly includes calcium,iron and clay matrix and there are few siliceous interstitial materials.Uniaxial compressive strength of rock has certain regional characteristics.Uniaxial compressive strength of rock is higher in the north of Zhejiang and Jiangxi generally and is lower in the south of Fujian and Jiangxi.However,volatility of compressive strength of rock sample among sample points is relatively stronger.Igneous rock has larger influence on studying rock characteristics of Danxia landform.Compressive strength of rock for sandstone and conglomerate containing rock debris of igneous rock is higher than that of rock without containing rock debris of igneous rock generally.Uniaxial compressive strength of rock has certain regional characteristics.Uniaxial compressive strength of rock is higher in the north of Zhejiang and Jiangxi generally and is lower in the south of Fujian and Jiangxi.However,volatility of compressive strength of rock sample among sample points is relatively stronger.Igneous rock has larger influence on studying rock characteristics of Danxia landform.Compressive strength of rock for sandstone and conglomerate containing rock debris of igneous rock is higher than that of rock without containing rock debris of igneous rock generally.Porosity experiment of rock sample indicates that the porosity plays a certain indicative role in rock difference of sandstone,conglomerate and igneous rock.Total porosity of sandstone and conglomerate in the same area is similar,but porosity(among particles)of sandstone is higher than that of conglomerate relatively and porosity(disconnected pores)in particles of conglomerate is larger than that of sandstone.Pore of volcanic-intrusive rocks intruding in the later period is lower,and forms water-resisting layer to play a protective role in rock of Danxia landform.Typical Danxia geomorphologic landscape in research area has positive landform and negative landform as well:positive landform mainly has isolated peak,Danxia peak cluster,Danxia red cliff,stone peak and stonewatch,modeling rock and colluvial clay;negative landform mainly has groove,grotto,cave,broken hole,natural bridge and cheuch.Danxia geomorphologic landscape also presents compound development characteristics.Research achievements have positive effect and significance for highlighting characteristics of typical Danxia geomorphologic landscape in the area,developing tourism resource with magnificent Danxia landform,presenting knowledge of Danxia geology and landform to tourists on scene,and promoting comprehensive,cross and integrated cooperative study of basic data survey of Danxia landform and multidisciplinary at the same time.