High-resolution Multi-index Stalagmite Records Of The Millennium Climate Events In Western Henan During The Last Deglaciation

The last desiccation period is the transition period of the earth’s climate from the last glacial to the Holocene,which occurred in the period of the Heinrich 1 event（H1event）,the B?lling-Aller?d event（BA event）and the Younger Dryas（YD event）and so on.At the same time,a number of millennial Centennial-Scale was also superimposed on this basis.Climate events are ideal periods to study climate change at different time scales.They are also important periods to explore the phase and related driving mechanism of different climate systems.The research on the driving mechanism,internal structure and transformation characteristics of climate catastrophe based on high resolution and multi index method has more practical application value in predicting future climate trend.In this paper,the stalagmite of Henan Luanchuan East Shiya cave in the northern monsoon region of China is selected as the research object.By analyzing the U/Th age,carbon and oxygen isotope records and trace elements of Stalagmite in the stalagmite DSY14041,the evolution records of East Asian Summer Monsoon with a coverage period of 14.2-10.5 Ka BP and the average discrimination rate of about 5a are established.Through the analysis,this study draws the following conclusions:1.Changes in theδ¹⁸O curve of stalagmite and the changes in the North Atlantic SST recorded by the Greenland ice core show synchronous changes in the millennium scale and in the range of annual errors.This period mainly recorded two millennium-scale climate abrupt events in the warm period of BA and the cold period of YD.On the macroscopic scale,the stalagmitesδ¹³C andδ¹⁸O curves are similar,but there are significant differences at the fine scale,suggestting that the carbon and oxygen isotopes may have different indicating significance.Theδ¹⁸O may indicate the local water vapor source in precipitation,andδ¹³C is more likely to reflect the local surface Changes in biomass and vegetation succession indirectly indicate the local dry and wet conditions.2.BA event,the overall trend of stalagmiteδ¹⁸O andδ¹³C showed a gradual negative trend.During the period,a total of four hundred-year mutation events were recorded.The internal details of the stalagmite were obviously different.Specifically:（1）the slope ofδ¹⁸O andδ¹³C recorded in the BA warm period is different,and theδ13C is obviously greater than theδ18O record.（2）The ending time of BA events recorded byδ¹³C was about 270 years earlier thanδ¹⁸O.The two were not synchronized.This may be related to the location of the study area northwards,which is related to the greater influence of the polar climate.The cooling of the climate may be a major factor in the deterioration of the environment and the sharp drop in biomass,and it’s also possible thatδ¹³C is more sensitive to the climatic environment thanδ¹⁸O.（3）The stalagmiteδ¹⁸O andδ¹³C both record the events of the century within the BA event.Among them,the event of the fairy is exceptionally prominent.The stature of this event calibrated by the stalagmite is 13965±71¹3794±81 a BP,and the duration is about 171a.3.The records ofδ¹⁸O andδ¹³C in the YD period all show a significant degree of bias.The records of stalagmiteδ¹⁸O show the characteristics of slow start and rapid end,during which four times of 100-year climatic oscillation events were superimposed.The start time of the YD event was not synchronized with stalagmiteδ¹⁸O andδ¹³C records.Inside the YD event,δ¹³C recorded 3 times of 100-year events with small amplitude.There was no obvious corresponding relationship betweenδ¹³C andδ¹⁸O.In addition,the trace elements in stalagmite showed that the ratio of Mg/Ca to Ba/Ca increased obviously at the millennium scale,while the ratio of Sr/Ca showed a decreasing trend.The macroscopic trends of Mg/Ca and Ba/Ca records and the internal 100-year-scale oscillations correspond well with theδ¹³C records.They verify each other’s credibility,indicating that trace elements carried the climate and environmental signals at that time.4.The results of power spectrum analysis showed that the main cycles of stalagmiteδ¹⁸O records were:1000a,100a,59a,40a,33a,26a,and 23a.The main cycle of theδ13C record is 1000a,62a.Wavelet analysis of the same set of data shows that there are significant 1000a,500a,and 200a cycles recorded on theδ¹⁸O,and there are distinct 1000a,500a,200a,and 128a cycles recorded on the stalagmiteδ¹³C.Theδ¹⁸O andδ¹³C records show different periods at different time intervals,but the commonality is a 1000a scale period that runs through the entire study period.The study found that the stalagmite display cycle is closely related to solar activity,indicating that changes in the solar radiation energy caused by the solar activity cycle affect the East Asian summer monsoon changes at different time scales of the last deglacial era.