近2000年来东亚夏季风突变的落水洞高分辨率石笋记录  

Abrupt changes of East Asian summer monsoon over the past two millennia from stalagmite record in Luoshui Cave,Hubei Province

作　　者：薛莲花 赵侃[1,2,3] 崔英方 梁怡佳[1,2,3] 杨少华 汪永进 Xue Lianhua;Zhao Kan;Cui Yingfang;Liang Yijia;Yang Shaohua;Wang Yongjin(School of Geography,Nanjing Normal University,Nanjing 210023,Jiangsu;Key Laboratory of Virtual Geographic Environment(Nanjing Normal University),Ministry of Education,Nanjing 210023,Jiangsu;Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application,Nanjing 210023,Jiangsu;Nanjing Institute of Tourism&Hospitality,Nanjing 211100,Jiangsu)

机构地区：[1]南京师范大学地理科学学院,江苏南京210023 [2]虚拟地理环境教育部重点实验室(南京师范大学),江苏南京210023 [3]江苏省地理信息资源开发与利用协同创新中心,江苏南京210023 [4]南京旅游职业学院,江苏南京211100

出　　处：《第四纪研究》2020年第4期973-984,共12页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:41702180、41571102和41572151);江苏省研究生科研与实践创新计划项目(批准号:KYCX19_0789)共同资助。

摘　　要：基于湖北落水洞石笋(LS45)7个^230Th年代结果和260个氧同位素测试数据,重建了近2000年来平均分辨率为6 a的东亚夏季风变化序列,该序列在280~800 A.D.、800~1400 A.D.和1400~1850 A.D.季风强度呈弱-强-弱的演变特征,分别对应于黑暗时代冷期(DACP)、中世纪暖期(MWP)和小冰期(LIA)3个典型气候期.LS45记录显示近2000年来东亚夏季风强度总体呈减弱趋势,并叠加数次百年尺度的振荡旋回.其中DACP和LIA并非持续几个世纪的连续弱季风时期,且内部还存在明显的数十年尺度强弱波动,δ^18O振幅范围约为0.6‰.在DACP向MWP转变期间,δ^18O值快速负偏,持续时间约40~50 a,变化幅度约0.7‰,指示夏季风突然增强.和尚洞、万象洞、Dandak洞的石笋记录以及Laguna Pallcacocha沉积物红度记录均显示了这一快速转变过程,暗示大尺度大气环流可能发生快速转型.进一步将中国石笋记录与太阳活动、 厄尔尼诺、大西洋海表温度和北半球温度指标记录进行对比,发现这些记录之间存在良好对应关系和相似特征,表明百年-十年际尺度季风变化可能与太阳活动、厄尔尼诺-南方涛动(ENSO)和大西洋多年代际震荡(AMO)变化密切相关.因此,本文推测ENSO和AMO可能是太阳活动影响亚洲季风变化的关键因子.Here,we derive a precisely ^230Th-dated and high-resolution stalagmiteδ^18O record from the Luoshui Cave(29°44'N,109°7'E;1071 m),Enshi,Hubei Province,Central China.This study region is located at the south slope of Daba Mountain Range and the northern edge of the subtropical monsoon region.The mean annual temperature in the cave is approximately 14.5℃with relative humidity close to 97%.The stalagmite(LS45)was collected in the chamber with a total length of about 237 mm.This sample is divided into two sections of 0~130 mm and 130~237 mm because of growth hiatus at the depth of 130 mm,so,the section of 0 mm to 130 mm is the research area.Besides,the growth rate is stable throughout the entire stalagmite,as is by the ^230Th dating results.When halved and polished,it is composed of pure and transparent calcite with homogeneous lithological characteristics.We present a continuous high-resolution record of EASM evolution from 280 A.D.to 1850 A.D.,roughly contains three periods of Dark Times Cold Period(DACP),Medieval Warm Period(MWP)and Little Ice Age(LIA).This paleoclimate time sequence was established by 7 precise ^230Th dates and 260 stable oxygen isotope ratios(δ^18O).The dating measurements were then conducted by multi-collector inductively coupled plasma mass spectrometer(MC-ICP-MS)at the Isotope Laboratory of Nanjing Normal University,the error is±2 sigma,and Isotope Geochemistry Laboratory at the Earth Observatory of Singapore,Nanyang Technological University.The oxygen isotopic analyses were run at the Isotope Laboratory of Nanjing Normal University with Finnigan MAT-253 mass spectrometer.Precisions forδ^18O is±0.06‰and±0.05‰forδ13C.Theδ^18O values of the stalagmite(LS45)vary from-8.2‰^-7.3‰and its maximum amplitude is close to 0.9‰,the average value is about-7.7‰,and the overall fluctuation range is small.The averageδ^18O values during the periods of 800~1400 A.D.is negative,implying relatively stronger ASM and corresponding to the period of MWP.And the averageδ^18O values during the

关 键 词：落水洞 中世纪暖期 季风气候突变 石笋 ENSO 

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