Paleoenvironment Evolution Of Hetao Basin Since The Last Glacial

The study area is located in Dengkou County,Hetao Basin,Inner Mongolia.It is a climate sensitive area affected by the advance and retreat of summer monsoon.Hetao Basin is a Cenozoic rift basin,in the center of which there are very thick Quaternary fluvial and lacustrine sediments,which provide good materials for paleoclimate reconstruction.Based on the study of paleoclimate change since the last glaciation in Hetao area,this paper can provide a reference for the prediction of climate and environment change in the future.In this paper,through the cataloging and sample collection of cores drilled in the Hetao Basin,using climatic alternative indicators such as particle size,color,magnetic susceptibility,organic carbon isotope and organic matter content,combined with ¹⁴C and photoluminescence?OSL?dating,we have studied the paleoclimatic evolution characteristics of the Hetao Basin since the last glacial period are compared with those of the Greenland ice core and stalagmite oxygen isotope curves,and the driving mechanism of climate change is preliminarily discussed.1.Through detailed stratified description and high-density sampling of the core of the drill hole in Dengkou,combined with the results of indoor particle size analysis,the cause of the sediment is judged,and the borehole 14-3.2m is considered to be dark brown,gray black,and green The lacustrine sediments mainly consist of gray silt and silty clay,and the brownish-yellow sand above 3.2m is aeolian sand.2.Using ¹⁴C and OSL dating,the sediments in Dengkou borehole were dated,and the development of Lakes since the last glacial period in Hetao Basin was inversed.In Hetao Basin,a thick typical lacustrine stratum is developed between 51.3ka B.P.and26.3ka B.P.,indicating the development of lakes at that time,while in 26.3ka B.P.,the lake dried up in the last glacial period.3.Using the grain size characteristics,magnetic susceptibility,chromaticity,and organic carbon isotope and organic matter content of borehole sediments as climatic substitute indicators,combined with the established chronological framework,the climate evolution of the Hetao Basin since the last glacial period is divided into four main stages:MIS3c?51-49ka B.P.?has a warm and humid climate;MIS3b?49-36 ka B.P.?becomes relatively cold and dry compared to MIS3c;MIS3a?36-26ka B.P.?has a warm and humid climate;MIS2?26-16ka B.P.?has a dry and cold climate.The characteristics of climate change are consistent with the lake evolution stage.4.Comparing the Dengkou borehole with the surrounding area,it has good consistency in terms of sedimentology and climatic stage division,indicating that the division of the paleoclimatic evolution stage in this study is regionally comparable.