Study On The Characteristics And Driven Mechanism Of The Younger Dryas Event Recorded By The Stalagmite From Western Fujian Province

The Younger Dryas(YD)event is a sharp cold event in the warming transition from the Last Glacial to the Holocene in the northern hemisphere,along with the high resolution of geological records,the regional difference about YD event study is rising.The previous study about YD event in the stalagmite record mainly in the southwest China and the middle and lower reaches of the Yangtze river.In this study,a stalagmite from Xianyun Cave,located in Fujian province which is affected by typical east Asian summer monsoon,will be chosen to reconstruct high-resolution proxy index of EASM during the YD,based on high precision 230Th dating and high resolution stable oxygen isotope analysis.The second purpose of this study is to discuss the Younger dryas event driven mechanism and evolution characteristics of the east Asian monsoon.This research based on 9 dating results and 288 oxygen isotope data from the Xianyun cave stalagmite XY?-14,present a ?18O record that reveals evolution characteristics of east Asian monsoon history from 11.01 to 13.4 ka B.P.,the ?18O records average resolution between 12.93 ka B.P.and 11.36 ka B.P.can reach 5.8 a.We draw a conclusion as follows:(1)The ?18O record of stalagmite XY?-14 in YD range from-7.26 ‰ to-5.54 ‰,the amplitude of 1.72 ‰,?18O records of YD period similar to the "W" type feature.In mid-YD,the stalagmites ?18O record is characteristic of the "three peak valley".After 12.2 ka B.P.,YD internal show monsoon gradually enhanced process.(2)The transition into the YD began at 12817 ± 40 yr B.P.and end at 11624 yr B.P.in the Xianyun record,consistent with the Greenland ice core record and other Asian monsoon stalagmite record.In the ?18O records of Xianyun cave stalagmites within three centennial-scale warming event,center as 12.57 ka B.P.,12.57 ka B.P.and 11.95 ka BP..(3)By comparing Xianyun cave ?18O record with other ice core record found that our stalagmite ?18O records monsoon evolution have a tight coupling relationship with northern high latitude climate in millennial-scale,has been suggest that the dominant effects of the north Atlantic meridional overturning in the YD event;On the other hand,east Asian monsoon stalagmites records are different from the high-latitudes records in centennial-scale monsoon evolution,it reveal that the Asian monsoon may be affected by factors outside the north Atlantic the climate system,the traditional THC theory seems to be difficult to explain the monsoon records of such graded trend.Perhaps the low latitude hydrothermal restructuring activities in the role of monsoon driving force should be more valued.