福建仙云洞石笋记录的19.0~17.6ka B.P.期间东亚夏季风增强事件  

An exceptionally strengthened East Asian summer monsoon event between 19.0 ka B.P.and 17.6 ka B.P.recorded in a stalagmite from Xianyun Cave,Fujian Province,Southeastern China

作　　者：马乐 肖海燕 张鑫 姜修洋[1,2] 蔡炳贵 Ma Le;Xiao Haiyan;Zhang Xin;Jiang Xiuyang;Cai Binggui(Key Laboratory of Humid Subtropical Eco-geographical Processes,Ministry of Education,College of Geography Science,Fujian Normal University,Fuzhou 350007,Fujian;Institute of Geography,Fujian Normal University,Fuzhou 350007,Fujian)

机构地区：[1]福建师范大学地理科学学院,湿润亚热带生态地理过程教育部重点实验室,福建福州350007 [2]福建师范大学地理研究所,福建福州350007

出　　处：《第四纪研究》2020年第4期926-935,共10页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:41672170);福建省自然科学基金项目(批准号:2017J01654);福建省高校新世纪优秀人才支持计划共同资助。

摘　　要：末次冰盛期回暖事件(19.0~17.6 ka B.P.)对于理解末次冰期终止机制具有重要意义.本文根据福建仙云洞石笋(XY7)的16个高精度^230Th年龄和327组δ^18O数据,重建了26.4~14.9 ka B.P.期间十年际分辨率的东亚夏季风演变过程,清晰地捕捉到了发生在末次冰盛期的夏季风增强事件.仙云洞记录指示这一强季风事件发生在19.0~17.6 ka B.P..尽管亚洲季风区各地洞穴石笋都明确记录了这一强夏季风事件,但仙云洞记录的振幅要小很多,仅为0.5‰.这可能与仙云洞位于受东亚夏季风影响的前缘地带,受低纬海洋水文循环过程影响强烈,降水同位素的季节性差异相对较小有关.通过与高低纬地区古气候记录的分析对比表明,末次冰盛期晚期受到太阳辐射升高、 北大西洋径向翻转环流增强和热带太平洋Super-ENSO的共同影响,东亚夏季风在19.0~17.6 ka B.P.期间显著增强.The warming episode(19.0~17.6 ka B.P.)during the Last Glacial Maximum(LGM)is a key to understand the mechanism of the termination of the last glacial period.This warming event has been reported in numerous records across the world,which often caused enhancement of a millennial-scale strengthed monsoon event.Here,we present a high-resolution stalagmite isotope(δ^18O)record from Xianyun Cave(25°33'N,116°59'E;970 m a.s.l.)in Fujian Province.The monthly mean temperature inside the cave is ca.17.5℃,relative humidity inside the cave maintains 100%throughout the year.The stalagmite(number:XY7)sample collected in the right branch gallery of Xianyun Cave is 330 mm long and 70~75 mm wide.Based on 16^230Th ages and 327 stalagmiteδ^18O data,we reconstructed the changes of East Asian Summer Monsoon(EASM)from 26.4 ka B.P.to 14.9 ka B.P.(before 1950 A.D.),yielding an average resolution of 35 a.The three stalagmiteδ^18O records of Xianyun cave show remarkable similarities during their overlapping growth interval.The replication of these records confirms that the stalagmites were very likely deposited under isotopic equilibrium conditions and theδ^18O signal recorded in these stalagmites is primarily dominated by climate change.The Xianyun Caveδ^18O record captures this millennial-scale strong monsoon events that occurred in 19.0~17.6 ka B.P.,which was also seen in other stalagmite records from Asian monsoon region.Compared with other monsoon sensitive records,the amplitude of Xianyun Caveδ^18O record is much smaller,i.e.,only 0.5‰.During this reconstruction period,the changes ofδ^18O are 1.7‰,1.5‰and 1.8‰in Xianglong Cave,Hulu Cave and Bittoo Cave,respectively.Low amplitude ofδ^18O at our site may be attributed to the fact that our study site has a small amplitude of the seasonal precipitationδ^18O,as it is located in the front area of the EASM and influenced by the low-latitude ocean hydrological cycle process.Co-varying patterns between our records and other high-and low-latitudes Paleoclimatic records sug

关 键 词：仙云洞 石笋 末次冰盛期 夏季风增强 

分 类 号：P597.2[天文地球—地球化学] P532[天文地球—地质学]