The MIS3 Millennium Scale Climate And Environmental Abrupt Events Recorded By Stalagmites In Qixingdong, Guizhou

The global climate during the last glacial period is characterized of the high frequency of millennial scale climate events.There are many records covering the world which have presented the abrupt climate changes,including northern hemisphere high latitude ice core ?18O records,tropical and sub-tropical SST records,corals in the sea,pollen,and many records of stalagmites.All the records are consistent in the beginning,the end and the duration of the events.For the internal structures and the details of the changes also have clearly recorded,where there are many high-resolution and precise dated climate records.By the means of investigating the relations between the inter-hemisphere,the high and low latitude,and the compositions of the climate system,we could analysis the driven mechanism behind the behaviors.The Asian monsoon is regarded as a crucial element in the global climate system,and plays a key role in the investigating process of the climate changes,compared with the northern ice core records and the tropical SST records,the speleothem has a correlation with them.The characteristics of the stalagmite as the media of climate are high precision and resolution,appropriate continuity,which make it possible to have a deep research in the evolution of the Asian monsoon,so we take the specificity of the high-resolution record from the southeast in China as the critical point to understand the climate changes better.In this paper,based on 15 U-Th ages,1140 oxygen isotopes and 2005 trace element data,we reconstruct an Asian monsoon evolution record of 35-64ka BP,which has an average resolution of 23 years.The stalagmite QXL from Qixing cave located in the Guizhou province in the southwest of China has recorded 9 millennial scale events(DO8-12?DO14?DO16?DO17?H4?H5).Compared to the speleothem records from the same and different caves during the same periods,important correlations are presented,which suggest that the QXL oxygen data could reflect the changes in Asian monsoon.Moreover,in consideration of the link between the records of ice core and SST,it's obvious that the climate changes between the high and low latitude is complex,so it's necessary to analyze the similarity and divergence between them in order to know the mechanism of the millennial scale events.Many authors have pay much attention on the mechanism behind the millennial scale changes.It's unsolved that the accurate explanation of the abrupt climate changes,because of the complexity of the climate system.It's been proved that there are many different cycles,millennial scale events are superimposed on centennial-decadal scale changes.The stslagmite QXL has an average resolution of 23a,through the scanned images of the transverse section,there are some periods,which is characteristic of porous,such as during the events of DO14?DO16?17,indicating of a high growth rate,especially during the DO14,which presented a resolution of 11a.The power spectrum analysis of ?18O data during the 50.5-55ka BP and 57.5-61ka BP identified some intense cycles of?250a??300a??520a,which were in coincident with the solar activity cycles appeared in the tree rings ?14C,it contribute to investigate the influence of solar activity in climate changes in centennial scale.Secondly,the stalagmite QXL has different response mechanisms for DO14-17 and the DO9-12,which were in space with precession cycles,showing that the trend of the ?18O curve was driven by solar insolation.Thirdly,the stalagmite QXL ?18O is more sensitive to the DO16?17 than the other records in the area of East Asian monsoon in China,the profile of the events is very clear,which indicates that the regional environment changes may have important influence on the oscillation amplitude of the ?18O.Based on the previous investigation summaries,most of the stalagmites collected from the Qixing Cave are identified to be aragonite-calcite stalagmites,that's to say the sedimentary minerals were not only calcite but also aragonite during the deposit courses of the stalagmites,the reason may be the environment changes induced by the abrupt changes in climate,which tend to be deposit aragonite minerals.The stable isotopes and the trace elements in the aragonite are disagree with those of the calcite in the concentration and the response mechanism.The ?18O is more sensitive to the climate changes in the amplitude than that of the calcite,which could use to research the links between the climate and the environment.