Study On The Origin Of Quaternary Loess And The Evolution Of Climate And Environment In Central Liaoning Province

The loess layer records a lot of quaternary climate and environmental information,which provides better research materials for studying the quaternary climate and environment.It is of great significance to study the past,present,and future environmental evolution as well as the glacial cycle and causes.This study mainly analyzes the loess in the area of Shenyang area in central Liaoning Province based on the climatic and environmental proxy indicators such as particle size,magnetic susceptibility,and geochemical elements.Sedimentary genesis of the profile and recorded climate and environmental evolution information.The main conclusions are as follows:1.After the photoluminescence age test,it was found that the profile was mainly deposited at 165.5ka.B.P to 61.19ka.B.P.It mainly consisted of the loess stage loess and the Malan stage loess.Corresponding to the late six-stage to early four-stage oxygen isotopes of the deep sea.2.The particle size data show that the particle size composition of the loess horizon in the study area is mainly silty clay,and the change of the particle size composition of the loess horizon is mainly affected by coarse silt.The grain size composition of the ancient soil horizon is mainly clay silt.The overall clay content varies greatly across the profile.The frequency distribution curve is unimodal,and a few samples show insignificant doublet.The probability accumulation curve can be seen from 2 to 3 intercept points,showing that the sample is also being moved by the ground while it is being handled by air suspension.3.The analysis of geochemical elements found that the leaching of K element was faster in the DT section,and there was no obvious leaching of Si,Al and Fe.According to the oxide ratio,it is found that the DT profile records the process of the profile gradually changing from warm and humid to cold drying.The weathering trend triangle chart shows that plagioclase is the first weathering and decomposition in the DT section.The chemical weathering minerals in the section are mainly illite and montmorillonite,which is in the middle stage of chemical weathering.4.Analysis of magnetic susceptibility data found that the profile consists of a layer of paleosol and two layers of loess.The magnetic susceptibility value of the loess layer is lower than that of the ancient soil layer,but the magnetic susceptibility value of the first layer of the loess layer is higher due to the later soil formation and the change of the superparamagnetic grain content.5.The genesis analysis of the samples on the section found that the section has obvious characteristics of aeolian sedimentation.The particle size composition,particle size parameter scatter plot and particle size discriminant function all indicate the aeolian genesis of the section.The sediments of this profile in several other typical loess profiles are similar in the content of macroelements,and the UCC standardized curve has a similar trend,which also indicates the wind genesis of the profile.6.After a series of testing and analysis,and comparison with the Zhaojiachuan loess profile in Lingtai and LR04?¹⁸O in Lingtai,the climate change trend of 61.19ka.B.P-165.5ka.B.P recorded in the DT profile was analyzed.Dryness changed to cold and arid.After entering the last interglacial period,it developed to warm and humid as a whole.In the early stage of MIS4,it showed alternating changes of warm,cool and humid and cold and arid.