RESEARCH ON OLD STALAGMITES BY ICP-MS ~(230)Th DATING AND PALEOCLIMATE RECONSTRUCTION IN DONGGE CAVE,LIBO,GUIZHOU

Advances in the research of stalagmites keep pace with the development of dating techniques,because new dating techniques aid paleoclimate reconstruction.Therefore,a precise chronology is the key for paleoclimate reconstruction based on stalagmites.Our study on old stalagmites(250ka) using the ICP-MS 230 Th dating method shows that stalagmite D6,D7,D9 of the Dongge Cave contain continuous and high resolution paleoclimate since 400ka ago.The 230 Th data serve as a standard for paleoclimate study in southwestern China for the last 500ka.This paper focuses on the relationship between stalagmite growth rate and paleoclimate reconstruction based on 135 precise ICP-MS 230 Th analyses of three big stalagmites in the Dongge Cave in southwestern China.The growth rate of stalagmites is negatively correlated with the δ 18 O record of SPECMAP and positively correlated with summer insolation at 25°N.Stalagmite growth rate was high in interglacial intervals,low in glacial periods,and more variable in transitional periods.Based on these results,we suggest that stalagmite growth rate may record changes in abrupt cold and warm events and thus could provide a useful proxy for long term records of paleoprecipitation and paleoclimate.