Research Of The Trace Element From A Stalagmite In Holocene At Jinfo Mountain,Chongqing

Global climate change is a evolving process,and it have an impact on human societies.In recent years,global climate change has been paid more and more attention from all walks of society.The Paleoclimatic environment is an important reference body of modern and future climatic environment evolution,the study and mastering the process and mechanism of paleoclimate evolvement can help predict the trend of future climate change,so that the research of global climate change in the past is gradually improved in the International geoscience field.The Holocene(Holocene)is a typical interglacial period and is an up-to-date stage in the long geological period,at this stage,human social civilization has been rapidly developed and reached a fairly high degree.The evolution of the Holocene climate,how the future climatic environment changes,will also affect the development of today's socio-economic,therefore,the Holocene and its climate change research,the relationship of the whole human society development,has extremely far-reaching significance.The Holocene paleoclimate research involves a wide range of fields,and the research on the evolution of the Holocene monsoon in Asia is one of its important hotspots.In the study of the Holocene monsoon changes in Asia,stalagmites is an important geological carrier.In the numerous climatic substitution indices of stalagmites,the study of oxygen and carbon isotope has matured,and the difference of the climatic meaning of oxygen-carbon isotope,which urgently needs the potential of other substitution indices of stalagmites.Previous studies have shown that the overall tone of the Holocene is warm and humid,the characteristics of the summer monsoon change as a weakening trend and the trend of continued weakening in the new world,but in the process of weakening,the performance is not smooth,there are several climatic oscillations,and the weak monsoon climate with rapid cooling and drying.The whole new World monsoon change trend and driving mechanism have been extensively explored,but for the weak monsoon events,in addition to the 4.2ka B.P.With8.2ka B.P.Events outside the other cold events are still not sufficiently valued,pending furtherresearch.This paper utilizes the high uranium content of HF01 stalagmite in the Heifeng Cave of Chongqing Gold Foshan,and obtains the 31 230 Th data with high precision through the experiment.Combining the trace element data,carbon and oxygen isotope data and gray scale data,the monsoon evolution process of the Holocene East Asian monsoon region was reconstructed.By comparing the trace element data,carbon and oxygen isotope data and gray data of stalagmites to the solar radiation energy change curves in the northern hemisphere summer,the responses of trace elements to the environment are analyzed To explore the evolvement regularity of Holocene East Asian monsoon recorded by HF01 stalagmites;Finally,the power spectral analysis and wavelet analysis are used to discuss the new World East Asia weak monsoon climate events reflected by HF01 Stalagmites,and its driving mechanism is analyzed,the main conclusions are as follows:1.The study found that the Sr/Ca ratios of stalagmites HF01 were basically consistent with the trend of 18 O reflecting the evolution regularity of East Asian monsoon.On the whole,there is a significant negative correlation,the Sr/Ca ratio of HF01 increases with the summer monsoon,the warmer and humid,the Sr/Ca value is also higher,indicating that the Sr/Ca ratio of stalagmites HF01 can be used as the surrogate indicator of East Asian monsoon change.The change of Sr/Ca ratio is related to the surface chemical weathering rate,and can respond to the summer monsoon intensity indirectly,indicating the dry and wet conditions outside the cave.The roof of Heifeng Cave is too thin and the retention time factor may have limited influence on Sr/Ca ratio and the mechanism of chemical weathering is enlarged.The Sr/Ca ratio of stalagmite HF01 is basically consistent with the change trend of 18 O,but the main control factor of Sr/Ca ratio has changed in different growth stages.Both in 8-9ka B.P.The correlation coefficient is very low.In the 9ka B.P.The former is significant positive correlation,8 ka B.P.After a significant negative correlation,the effect of the Sr/Ca mechanism is more complex,and when discussing the change of Sr/Ca ratio,the two mechanisms of the surface chemical weathering rate and retention time are diametrically opposed to the wet and dry conditions of the Sr/Ca.Therefore,in the use of Sr/Ca ratio to explore environmental significance can not be simply attributed to temperature,precipitation or vegetation factors,but should be considered as a variety of factors affecting the different mechanisms of the superposition and offset results.The use of Sr/Ca to reconstruct ancient climate needs caution,especially to pay attention to the multi-index comparative study,analyze its specific mechanism and prevent miscarriage.2.Mn/Ca;Ni/Ca ratios and 18 O have a basically consistent trend of change,it can reflect the evolvement regularity of the Holocene East Asian summer monsoon,but the fluctuation of the millennium scale and the content of MN elements in the sediments of the lake in Zhanjiang,Guangdong Province have better correspondence,and it is found that it may be related to the air dust caused by strong winter.V/Ca,Cr/Ca,Fe/Ca,Cu/Ca ratio change is different from the SR,Mn,NI and other elements,its change amplitude is larger,even the increase can reach several decades.V/Ca,the possible mechanism of the change of ratio of Cr/Ca,Fe/Ca and Cu/Ca is: The water dynamic condition is better in the early and Middle Holocene,the microelement and impurities in the overlying strata and soil are more,at this time the drop rate is faster,the stalagmite grows faster;the late Holocene,the opposite.3.?18O,?13C,gray scale and Sr/Ca ratios of stalagmite HF01 support the view that ITCZ North-South migration drives the change of Asian monsoon,which indicates that the evolution of the monsoon climate is mainly influenced by the macro-control of solar radiation energy on the orbit scale.The carbon and oxygen isotope,stalagmites gray and microelement ratio of HF01 stalagmites to the North Atlantic 9 Cold events(bond events)have varying degrees of record,the wavelet analysis found that ?18O,?13C,Gray and trace elements of the ratio of the quasi-1000-year cycle.But bond events are not clear about the driving mechanism of the Asian monsoon.The new century-decades-scale cycle of climate change has responded sensitively to the driving role of solar radiation,and can be well reflected in the gray and Microelement Records of stalagmites HF01,REDFIT37 spectral analysis program detected gray and trace elements in many hundred years-decades scale cycles can correspond to the main cycles of solar activity.