末次冰期亚洲季风千年尺度事件的频谱特征分析  

Spectral characteristic of the Asian monsoon millennial-scale events during the Last Glacial

作　　者：王真军 陈仕涛[1,2,3] 周学琴 梁怡佳 汪永进 Wang Zhenjun;Chen Shitao;Zhou Xueqin;Liang Yijjia;Wang Yongjin(School of Grography,Nanjing Normal Univrsity,Nanjing 210023,Jiangsu;Key Laboratory of Virtual GeographicEnrironment(Najing Normal Unirersity),Ministry of Education,Nanjing 210023,Jiangsu;Jiangsu Center for Collaborative Innotation in Geographical Information Resource Development and Application,Nanjing 210023,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

出　　处：《第四纪研究》2020年第4期851-863,共13页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:41572340,41571102和41931178);江苏省高校优势学科建设工程项目(批准号:164320116)。

摘　　要：基于神农架永兴洞3支石笋氧同位素记录,拼接重建了末次冰期88~22 ka B.P.平均分辨率达70 a的东亚季风演变序列.本文以小波诊断技术为基础,对去除65°N夏季太阳辐射和72 ka异常事件影响的石笋δ^18O进行了多时间尺度分析.小波频谱分析结果表明,末次冰期亚洲季风具有明显的近8 ka、4 ka、2 ka左右的周期.其中近8 ka周期是唯一一个贯穿整个末次冰期的显著周期.小波方差分析结果也显示该时段仅有1个突出的峰值,对应时间约为7.7 ka.进一步分析发现这个周期组分其实也出现在格陵兰冰芯δ^18O和南极温度变化中,可能被年龄误差和异常事件所掩盖.已有的千年尺度机制难以有力地解释该周期组分,我们利用外差法对轨道参数的周期进行分解,获得16 ka周期,这个周期的一半刚好与发现的8 ka周期相匹配.因此,地球轨道参数单独或共同作用,引起海表温、大冰盖、海洋/大陆生态系统的变化,通过大气、大洋等环流作用,从而产生地球气候系统轨道和千年尺度的振荡.The Greenland ice cores have done a lot of research on the spectral characteristics of millennial-scale events during the Last Glacial.However,there are problems such as monotonous spectrum period(focused on 1~2 ka),monotonous research area(limited to the Northern high latitudes),and monotonous research interval(limited to the high-resolution interval since 38 ka B.P.),which indicates that the spectral characteristics of the millennial-scale events during the Last Glacial need to be further studied.Based on the publishedδ^18O record of three stalagmites(No:YX46,YX51 and YX55)from Yongxing Cave(31°35'04″N,111°14'42″E;750 m a.s.l.),Hubei Province,China,the East Asian monsoon evolution sequence with an average resolution of 70 a over 88~22 ka B.P.was reconstructed,which attempt to provide a new understanding to the dynamic mechanism of millennial-scale events during the Last Glacial.After analysis,we believe that the mechanism of the 72 ka event is different from other events and may interfere with the results of spectrum analysis.By eliminating the influence of 65°N insolation and 72 ka anomaly event,the Morlet wavelet analysis showed that the Asian monsoon had obvious periods of nearly 8 ka,4 ka and 2 ka during the Last Glacial.Besides,the nearly 8 ka-period is the only significant period throughout the Last Glacial.Meanwhile,this conclusion is also supported by the wavelet analysis results of the stalagmite splice records from Sanbao Cave and Hulu Cave,indicating that the nearly 8 ka period recorded by the stalagmites in Yongxing Cave has regional universality.Compared with the bipolar ice core records,the spectral characteristics of Asian monsoon stalagmites and Antarctic ice cores have great similarities,and the outstanding performances show nearly 8 ka cycle throughout the Last Glacial.At the same time,we further found that the nearly 8 ka cycle found in the mid-low latitude also appeared in high latitudes such as Greenland and Antarctica,so we believe that this periodic feature should be global.Howeve

关 键 词：洞穴石笋 末次冰期 亚洲季风 千年尺度事件 近8ka周期 

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