Preliminary Analysis Of Quartz Sand Surface Texture From The Qidingshan Profile In Southern Liaoning Province

The Qidingshan profile is chosen as the research object based on field investigation in southern Liaoning province.The surface texture of quartz sand from bedrock,red weathered crust and the overlying loess from the Qidingshan profile are systematically observed by scanning electron microscope(SEM).Qualitative analysis and quantitative analysis were used to analyze the grinding roundness,mechanical surface texture,chemical surface texture and mechanical-chemical surface texture of quartz sand.Then on the base of these,the surface texture and combination characteristics of quartz sand are analyzed.The material source,depositional mechanism and sedimentary environment of bedrock,red weathered crust and the overlying loess from the Qidingshan profile are researched according to the relationship between the modern sedimentary environment and quartz sand surface texture and combining with field investigation,the grain size and chemical element other identification data of the sediment.(1)The grinding roundness of quartz sand which come from bedrock,red weathered crust and the overlying loess from the Qidingshan profile are mostly in sub-angular shape and developed mechanical surface texture,chemical surface texture and mechanical-chemical surface texture of quartz sand at different levels.The mainly quartz sand mechanical surface texture are scale conchoidal fractures,straight and curved grooves,mechanical V-shaped,dish-shaped pits,mooned pits,mechanical pits,flat cleavage plane,parallel step-like fractures,striations,parallel cracks,meandering ridges,upturned plates,abrasion fatigue,underwater polishing surface that quartz sand are from bedrock,red weathered crust and the overlying loess from the Qidingshan profile.The quartz sand from bedrock,red weathered crust and loess are developed texture of underwater environment,and growth of high-energy underwater environment characteristics.It is different from the bedrock and the red weathering crust that quartz sand from loess are developed lots of aeolian environmental characteristics.The occurrence frequency of dish-shaped pits on coarse quartz sand surface is higher than that in middle-fine quartz sand surface and mechanical pits in middle-fine quartz sand surface more frequently than that in coarse quartz sand surface.In addition,the frequency of flat cleavage plane of middle-fine quartz sand surface is far higher than that of the coarse quartz sand from red weathered crust and loess from the Qidingshan profile.Quartz sand chemical surface texture is developed scaly exfoliation,dissolution pits,dissolution grooves and directional dissolution pits by corrosion and is growth of siliceous balls,siliceous scales,siliceous films and crystal growth by precipitation.But the degree of chemical modification of bedrock,red weathered crust and the overlying loess are different.In general,the red weathered crust quartz sand is chemically reformed to a higher degree,followed by bedrock quartz sand.The degree of transformation of loess quartz sand by chemical action is lower than that of red weathered crust and bedrock quartz sand.They are formed different degrees of protuberance on the surface of quartz sand experienced different degrees of mechanical action and chemical action from loess,bedrock and red weathered crust from the Qidingshan profile.Generally speaking,the quartz sand of loess,bedrock and red weathering crust are mainly middle protuberance,but occurrence frequency of middle protuberance on loess quartz sand surface is much higher than that of red weathering crust,slightly higher than bedrock.In addition,cohesive particles are commonly found on quartz sand surface from loess,bedrock and red weathered crust and appear mostly on low-lying parts of quartz sand surface.(2)The material of the bedrock substance from Qidingshan profile is mainly from marine sediments,and another part comes from terrigenous detritus.The carbonate deposits are excluded and disturbed,which leads to the low purity of the limestone in the seven top mountain sections because of the continuous input of terrigenous detritus.At that time,it was an epicontinental sea environment that the concentration of Mg2+ was high in the sea water,forming a high magnesium argillaceous limestone.The chemical action of quartz sand from bedrock is lower than that of red weathered crust.It also reflects that the temperature and humidity of the bedrock deposit are lower than the paleoclimate environment during the development period of the red weathered crust.And the paleoclimate environment during the formation period of bedrock is a relatively warm and humid climate.(3)Red weathering crust is formed by acid insoluble substance which is produced by the process of carbonate minerals are quickly leached that caused by the below carbonate rocks was in long-term weathering,and quartz sand in red weathered crust are mainly derived from the flint clumps which is embedded in the bedrock,through a comprehensive study of quartz sand surface texture and composition characteristics,similarity of formation environment and chemical composition about red weathered crust and bedrock from the Qidingshan profile.The stage of CIA experience strong-weakening-enhancement – weakening and the chemical action of quartz sand experience larger-decreasing-increasing – decreasing from the top to the bottom of red weathered crust.And it is shown that the change of weathering strength of red weathered crust in the four stage which is strong weathering-weathering attenuation-weathering reinforcement-weak weathering,and the chemical action of quartz sand also changes in four stages which is strong-weakening-enhancement – weaker.Both of them indicate the paleoclimate environment of southern Liaoning province during the development period of red weathering crust has experienced the process of evolution which is hot and humid-warm and wet-return wram-relative warm humidity.(4)Loess of the Qiqingshan profile is mainly derived from marine sediments at the bottom of the Bohai sea regression during the ice age deposited by a short distance of wind.The CIA and the chemical action of quartz sand of loess are significantly lower than that of red weathered crust,indicating that the temperature and humidity condition during the period of loess deposition is much lower than that of red weathered crust,and the whole climate is warm and cool.(5)Through a comprehensive study of quartz sand surface texture and composition characteristics,similarity of formation environment and CIA about red weathered crust and bedrock from the Qidingshan profile,it indicates that the environment of red weathered crust and loess deposition is quite different,and indicating that the climate and environment of southern Liaoning province has changed from High temperature and humidity on the late the Tertiary period to whole warm and dry on The Quaternary period.