Developmental Characteristics And Significance In Geoscience Of Karst Caves In Yunnan Plateau

The study of caves tends to focus on the formation and evolution of individual caves.With the advent of digital elevation models(DEM)and the development of geospatial information system(GIS)technology,large-scale geomorphological analysis studies are possible.The Yunnan Plateau is one of the concentrated distribution areas of karst caves in China.Based on the ArcGIS software platform,this paper uses ASTER-GDEM data to extract the landforms of Yunnan plateau and other geomorphological parameters in Yunnan and its neighboring areas,and validates it by field investigation in the wild.At the same time,the geographical location of the karst caves(group)in the superimposed study area and the spatial analysis of the stratum,lithology,structure,climate,hydrology,etc.,and the spatial differences between the karst caves in different geomorphological sites are used to clarify the region.The spatial distribution,development mechanism and landscape differences of the inner karst caves reveal their scientific value and geoscience significance.Research indicates:(1)The Yunnan Plateau topographical surface is extracted to Grade 3.Grade I landforms(2300~2430m)are scattered in the northeastern Yunnan area and are similar to the residual peak top surface;Level II landforms(1800–2080m)are mainly distributed in the eastern and middle Guizhou provinces,showing large fluctuations.The plateau surface of the plateau,a series of relatively uplifted erosional mounds,and a series of relatively uplifted middle-lower mountains and relatively collapsed intermountain basins between the relatively collapsed karst fractured basins;the Grade III landforms(1450-1600 m)are concentrated.Located in the southeast of Yunnan Province,it is represented by the karst peaks and peak topography with similar peak heights.Combined with field surveys,it is found that the Grade II landforms widely distributed in the central and eastern parts of Yunnan are the major planes of the Yunnan Plateau,but more evidence is needed.(2)80 ka rst caves(clusters)have been found in the study area,which are distributed in the altitude range of 830 m to 2900 m,of which there are 46 on the plateau and 34 on the slope.Judging from the regional differences,the central and eastern parts of Qujing and the southeast part of Kunming are densely populated.The density of Chuxiong Prefecture,Yongsheng County of Lijiang City and the southwestern part of Yuxi City are low,showing a spatially uneven distribution.(3)Karst caves in the study area are mainly distributed in the Triassic and Permian strata;limestone and dolomite dominate;cave development within 3km from the fault is obviously controlled by the fault structure;the climate is warm and humid with abundant precipitation,It has created favorable climatic conditions for the development of karst caves;caves within 5km from major rivers accounted for 38.75% of the total number of caves in the study area,indicating that the distribution of caves has strong hydrophobic properties,and provides a driving force for cave development.(4)The caves on the plateau landform usually undergo the submerged cave stage,the water cave stage and the seepage cave stage.The caves on the slope belt generally experience the phases of cave flow,cave flow and sunroof,the valley bridge and the canyon flow stage.(5)The karst caves in the Yunnan plateau are mostly multi-layered cave systems in the form of horizontal corridors,usually 3 to 5 stories;the slope zone is the main distribution area for deep caves and large caves,but cave delamination is not obvious.The sediments on the surface of the plateau are mainly secondary chemical deposits.The landscape is dense and well-preserved.The caves on the slope belt are large in scale but poor in preservation.In addition,seven ancient human cave sites in the area are located in the relatively dry,high humidity caverns on the plateau.(6)Karst caves are not only an important basis to reflect regional tectonic evolution and plateau uplift,but also an important trace of the evolution of the geomorphology of the Yunnan plateau.Cave sediments are also good “materials” for studying climate and environmental changes in the Yunnan plateau.