The Record of Climatic Change from Stalagmite in Xiashuilong Cave of Xuanwei City Since 46ka

Key words: 
• stalagmite /
• paleoclimatic change /
• Xiashuilong cave of Xuanwei city

Abstract: Stalagmites in karst caves are the main carrier of paleoclimatic and paleoenvironmental records with the high resolution.The high resolution information on paleoclimatic change from 46.1ka B.P. to 2.75ka B.P. has been obtained through α-counting U-series dating and carbon and oxygen isotopic analysis of No.1 stalagmite in Xiashuilong cave of Xuanwei city. The record of its ages and δ ¹⁸ O value in the change of the vertical section have obvious rhythm characteristics and can be compared with the oxygen isotopic records of deep-sea cores at Ⅲ,ⅡandⅠ stages. It reflects that the climatic changes in Xuanwei area coincides with the fluctuation of global paleoclimatic change.But here is the sensitive area of the climatic change and also the specific region of the reciprocity between East Asian monsoon and Southwest monsoon,and the feature of the climatic change caused by them was obvious in this region.The overall last glaciation from 46.1ka B.P. to 8.1 ka B.P. show warm climate trend in the mass,and 10.25 ka B.P. is the coldest of the end point of Younger Dryas event.The Holocene Megathermal period during 7.1 ka B.P. and 3.7 ka B.P. are the climate of temperate (warm)-wet.The climate during 3.7 ka B.P. and 2.75 ka B.P. has obvious trend of decreasing temperature to follow the weakness of the sun radiation and the Southwest monsoon intension.Furthermore,the cold and warm change of the climate indicate that the main sediment cycles in stalagmite take the periodicity change as ten thousand years, thousand years and hundred years, and sub-cycles in stalagmite show the periodicity change as thousand years and hundred years.