The Study On Pretreatment Of Grain Size Distribution Characteristics And Analysis On Weathering Characteristics Of The Red Weathering Crusts On Liaodong Peninsula Coastal

As an important structural features of sediments,because of the differences in depositional environment、terrain、transporting mediu、hydrodynamic conditions,the grain size distribution of sediment transported by different ways,so it has important implications for inferring geographical environment for the formation of the weathering crust.Red weathering crusts are desilication ferrallitic-rich weathering crust weathering products in hot and humid climate,chemical elements in the soil environment and weathering with a different intensity profiles showed significant changes.Chemical element migration patterns combined with the grain size distribution can be more depth study the characteristic and paleoenvironmental of the red weathering crust.Weathering crust volume content of each particle size are the basis for the correct interpretation of its distribution characteristics,the reliability of the results not noly based on the analysis and testing methods,but also on the sample pretreatment.Red weathering crust for its strong weathering,secondary clay minerals and oxides generated during the growth easily lead to cementation.Different types of sediment mineral composition have a clear difference in the type of cement.For the geographical environment in Northern the grain size distribution of its red weathering crust has big differences with Loess deposits、Tertiary red clay、Beaches and Marine sediments,etc.The pretreatments for them may not suitable for the Liaodong Peninsula’s red weathering crust grain size analysis,so the premise to highly dispersed rely on a appropriate pretreatment method.Select the weathering crust profile of Shicao village of Chenshantou on Liaodong Peninsula for study.Considering the sample’s quality 、 H2O2 、 HCl 、 chemical reaction environment 、 dispersants 、 ultrasonic factors etc,designed 17 kinds of pretreatment methods.The results show:2.5-3.0g suite for sample quality measurement to Liaodong Peninsula;15ml of 30% H2O2 may substantially remove all organic matter in the test sample;HCl reaction and dispersion effect in boiling is better able to eliminate the substance carbonate in test sample than at room temperature,the set of parallel comparison test is more stable;8ml volume ratio of 1:3 HCl can ensure carbonate hydrochloride salts complete reaction to 0.25 g sample,dispersion effect substantially same with 15 ml.10ml concentration of 0.02mol/L(Na PO3)6 enables a high degree of particles dispersion;ultrasonic vibration for two minutes can achieve the best results.After choose the appropriate pretreatment to take all layers of soil samples to experiment,the grain size frequency curve are 4-6,mode appears in 0.5Φ、2Φ, peaks of sand and silt parts very narrow,shows a sharp steep state, skewness is 0.1-1,sorting for the grain size is poor,coarse grain size relatively much.Test results show that the chemical elements,the section contains an average of about 6% carbonate,so the weathering crust red of Shicao village in Chengshantou in a semi-weathered state.Chemical index of alteration changes complicated with the depth shows that the development process of the red weathering crust of chengtou on Liaodong Peninsula is uneven,it can be inferred that Liaodong Peninsula had been a period of warm and humid climate,and then turns cold,lack of precipitation,weathering basic pause.