Geochemical Characteristics Of Elements During Rock Weathering And Soil Formation In The Central Inner Mongolia

Ecological geology is a discipline that studies the interaction between surface ecology and its dependent geological environment.It can reveal the geological influence mechanism of various ecological patterns and ecological processes,and put forward corresponding ecological protection and control measures from the perspective of geology.The surface ecology is the common product of atmosphere,hydrosphere,lithosphere,soil sphere and biosphere.The weathering process of bedrock is the main form of the interaction between the surface layers.The physical,chemical and biological effects in the process continuously affect the surface ecological environment and change the surface pattern,It also provides important environment and material resources for the sustainable development of ecosystem.The central part of Inner Mongolia is a typical ecotone of agriculture and animal husbandry in China.The ecological environment is relatively fragile.Land desertification and soil erosion have been serious ecological environmental problems in this area.The altitude of the study area is similar,but from east to west,the vegetation characteristics show the ecological changes of trees,shrubs and grass,the vegetation coverage gradually decreases,and the soil desertification is gradually serious.There is a lack of systematic study on the eco geological mechanism of this phenomenon.Therefore,from the perspective of geochemistry,this paper studies the distribution characteristics and migration rules of elements in bedrock weathering profile under different vegetation characteristics in the region,analyzes the influence of climate,lithology,landform and wind erosion,reveals the soil formation and wind erosion mechanism in the region,and interprets the coupling relationship between eco geological characteristics and ecological environment,It can provide scientific basis and service for further study of soil development and evolution characteristics and ecological environment protection in this area.In this paper,the rock weathering profile in Dongsuqi-Keqi area of Inner Mongolia is taken as the research object.By analyzing the lithologic characteristics of parent rock in different profiles and the distribution and evolution characteristics of major elements and trace elements in the profile,their variation rules are discussed,and the evolution process of elements in the process of rock weathering and soil formation is discussed.In the study area,nine rock profiles with four different lithology and different landform locations were selected,and soil layer,semi weathered layer and bedrock layer samples were collected from each profile.The 32 samples were tested for elements,9 bedrock samples were identified under microscope,and 12 soil samples were tested for grain size.On this basis,the geochemical properties and evolution characteristics of elements in the profile were analyzed:(1)During the weathering process of the rock profile in Dongsuqi-Keqi area,Inner Mongolia,the geochemical behavior of most elements is migration and leaching,and only Fe and Rb elements are slightly enriched.(2)The CIA value of the section in the study area is between 50-60,which is obviously lower than that in the south of China,and the chemical weathering degree is lower in the cold and dry climate.(3)Compared with the influence of parent rock lithology and climate on rock weathering,wind erosion and geomorphic factors are the most critical factors affecting rock weathering in the study area.(4)The weathering degree of rock section in Keqi area is higher than that in Dongsuqi area.The specific characteristics reflected in the ecological environment are as follows: the soil layer in Keqi area is thick and stratified,and there are many kinds of vegetation,and the rising trend is flourishing;In Dongsu banner area,the soil layer is thin,and the vegetation is mainly grass,with short growth and low coverage.