Paleoclimatic Reconstruction In Dengkou Area Since The Last Deglaciation Based On GDGTs

The climate change since the last deglaciation,as one important part of the Quaternary period,has largely affected the surface ecological environment.Therefore,the reconstruction of the paleoclimate can provide guidance for mankind o cope with the future global climate changes.Dengkou is located in the transition zone between monsoon and non-monsoon area and is very sensitive to climate change.However,the paleoclimate reconstruction in this area still lacks the introduction of new methods.In view of this,this article selects the Dengkou lake sedimentary borehole T2 in Inner Mongolia as the research object,combined with dating data,and based on regional GDGTs,quantitatively reconstructs the climate evolution process in the Dengkou area since the last deglacial period,and analyzes its climate formation mechanism.Preliminary discussion.Mainly have the following knowledge:(1)The sediment chromaticity parameters a*and b*of borehole T2 showed a good correlation,reflecting information of paleoenvironment changes such as temperature and precipitation.Results of organic carbon isotope indicated that this area were dominated by C₃plants,and the climate was generally colder.(2)The annual average temperature based by the topsoil b GDGTs can reflect the changes in temperature.The reconstructed average annual atmospheric temperature is 9.30?,in line with the change oh paleotemperature in Dengkou area.The paleorainfall of Dengkou area according to b GDGTs based formula in China's regional soil,is larger than the average rainfall of study area whereas suggesting the trend and magnitude of rainfall changes.(3)The paleo-temperature and paleo-rainfall in the Dengkou area changed simultaneously,reflecting the same tendency of rain and heat.Based on multiple climate indicaors the paleoclimate changes in the Dengkou area since the last deglaciationl can be reconstructed.The climate from the last deglacial period to the early Holocene changed gradually from cold and dry to warm and humid.From the early Holocene to the middle Holocene,the climate was warm and humid,and the climate since the mid Holocene became driere and warmer.(4)Regional comparative analysis showed that the paleoclimatic evolution trend of the study area is consistent with adjacent areas.However,the changeable climate in this area should be largely controlled by the summer solar,which indirectly affected the plant types and ancient rainfall trends in the entire study region.