Classification Of Karst Valleys Based On Geological Basis

Karst rocky desertification is one of the most serious eco-geolo gical enviro-nmental problems,and the control of rocky desertificati on has reached the sta-ge of overcoming difficulties.Karst trough-v alley area is the largest area of ka-rst distribution in southern China,and its natural background is complex.Trou-gh-type folds and blo ck-type folds constitute Jurassic mountain-type folds,and Jurassic m ountain-type folds are controlled by structures.Modern studies gener a-lly believe that these folds are controlled by structures.The Juras sic mountain-t-ype folds are formed in the process of detachment,a nd the trough-type folds a-re also controlled by faults.The tectonic types,lithologic assemblages and strat-igraphic structures play a le ading role in the geomorphology of the karst troug-h-valley area an d its corresponding natural environment.The single model of c-ontr olling rocky desertification has encountered many problems.The stu dy of tr-ough-valley types in the area can help us understand the g eology of the karst trough-valley.The basic situation,so as to find out the natural background of karst trough and valley,clarify the differences of ecological environment within the region,provide a more solid theoretical support for the study of rocky de-sertification in the region,and provide suggestions for the work of harnessing according to local conditions.The karst trough-type trough-valley area is the la-rgest area of distribution in the karst trough-valley area.This paper takes it as the research point of view,reveals the diffe rence of geological foundation and morphology in the karst troughvalley area through the study of the type of t-he area,so as to pro vide a theoretical reference for the further study of the ty-pe of the region and the whole karst trough-valley area.Geomorphological morphology and lithological basis play a con trolling role in the development of karst and are also the basic con ditions for the occurren-ce of rocky desertification.Starting from th e geological basis,this study analy-zed the internal differences of k arst trough-valley area,followed the basic clas-sification principles o f morphological similarity and genetic consistency,and to-ok the pl ane shape,structural type,lithologic combination and stratigraphic st r-ucture of folds as four comprehensive indicators.Taking the analy sis of geologi-cal profile maps and the summary of regional geologi cal conditions as the ma-in research methods,the classification of k arst trough-valley areas is carried o-ut.In order to analyze the diffe rences of different types of geomorphological morphology,the typic al types of areas are selected for the analysis of geomorp-hological morphological characteristics,and the fractal theory is used to veri fy the geomorphological features by projection covering method.Ba sed on the an-alysis of soil types and land use types in typical areas of trough-valley type,the differences of ecological environment i n typical areas of trough-valley type were analyzed.The main resul ts are as follows:1.Typical karst trough valleys are extracted and classified acco rding to th-e four comprehensive indexes of fold plane shape,struct ural type,lithologic co-mbination and stratigraphic structure.Throug h classification,the karst trough v-alleys can be divided into three categories: the core trough of Cambrian dolo-mite,the wing trough of Cambrian dolomite,the core trough of Triassic limest-one and th e Triassic trough.Limestone wing trough,Permian limestone core tr-ough,Ordovician limestone core trough,fault Triassic limestone co re trough;s-ub-categories are: Cambrian continuous dolomite core tr ough,Cambrian contin-uous dolomite wing trough,Triassic interbed ded pure carbonate core trough,Tri-assic interbedded pure carbonate wing trough,Triassic interbedded pure carbonate core trough,Trias sic interbedded pure carbonate wing trough,Triassic interb-edded sa ndwich trough.Pure carbonate core trough,Triassic interlayer type su-bpure carbonate wing trough,Triassic interlayer type impure carb onate core tro-ugh,Triassic interlayer type impure carbonate rock w ing trough,Permian contin-uous limestone core trough,Ordovician c ontinuous limestone core trough.2.Five typical trough-valley areas were selected for morphological analysis.It was found that the trough-valley morphology in the core of Cambrian dolo-mite was the most complex and diverse,wi th the largest slope and roughness.Fractal dimension values of five trough-valleys were obtained by fractal calcula-tion.The fractal di mension values were basically consistent with the morpholo-gical ch aracteristics of five typical trough-valleys.3.Selecting three typical trough-valley areas for soil type and land use ty-pe analysis,the results of soil analysis highlight the cha racteristics of the distri-bution of limestone soil in trough-valley of limestone core of Triassic strata a-nd its parent material are strongl y related;there are significant differences in la-nd use types of the three trough-valleys,even in the adjacent geographic locat-ion,ther e are significant differences between the two trough-valleys with si mil-ar climatic conditions.Different.