东亚季风气候对Heinrich2事件的响应:来自石笋的高分辨率记录  

An event of the East Asian monsoon responding to Heinrich Event 2:Evidence from high-resolution stalagmite record

作　　者：陈仕涛[1] 汪永进[1] 吴江滢[1] 刘殿兵[1] 

机构地区：[1]南京师范大学地理科学学院江苏省环境演变与生态建设重点实验室,江苏南京210097

出　　处：《地球化学》2006年第6期586-592,共7页Geochimica

基　　金：国家杰出青年科学基金(40225007);江苏省研究生创新计划项目

摘　　要：据湖北省神农架天鹅洞一支石笋11个230Th年龄和254个δ18O数据,建立了28.5～22.0kaB.P.同位素分辨率平均约30a的东亚季风气候变化序列。该石笋δ18O曲线与南京葫芦洞石笋记录在重叠时段基本一致,说明本区石笋δ18O反映了区域性东亚季风经向环流特征。在24.3kaB.P.左右,石笋δ18O明显正偏,持续时间近1ka,指示一次显著的弱夏季风事件,与北大西洋倒数第二次冰漂碎屑事件(Heinrich2)同步发生,可视为东亚季风气候对H2事件的响应。高分辨率的δ18O序列揭示了H2事件的内部结构特征:(1)事件发生的突变性,石笋δ18O记录指示事件发生时在100a内δ18O从-8.59‰迅速正偏为-6.75‰,振幅达1.84‰;(2)事件结束的渐变性,δ18O正偏到-6.75‰后便以阶梯状缓慢负偏到-8.86‰至事件结束,持续时间近900a。这一过程与末次盛冰期东亚季风气候H1事件表现的季风强弱转换方式基本一致,说明末次盛冰期东亚季风气候H型事件具有共同的内部结构特征。研究表明,末次盛冰期东亚季风气候H事件的突变可能受北大西洋驱动并经青藏高原冰川变化放大。One stalagmite （SW4） was collected from Swan Cave situated at 1 600 m above sea level in Shennongjia area. Eleven sub-samples were dated by Finnigan MAT 262-RPQ type meter at the Isotope Laboratory of Geology and Geophysics Department, Minnesota University, USA, and 254 δ^18O data were conducted with MAT 253 mass spectrometer linked with automatic equipment at Isotope Lab, Nanjing Normal University. These results provide a 30-year-resolution paleoclimate record of East Asian monsoon during a time interval from 28.5 to 22. 0 ka B P of the Last Glacial Maximum. In order to check the reliability of stalagmite SW4 δ^18O record, it was compared with stalagmite MSD from Hulu Cave in Nanjing between 28.5 and 22.0 ka B P. The general replication of δ^18O values in this interval suggests that variations of the stalagmite δ^18O record from Swan Cave reflect large spatial changes in circulation strength of East Asian monsoon. There was a remarkable weak summer monsoon event at ～ 24.3 ka B P in our stalagmite δ^18O record, which, lasting about 1 ka, shows a conspicuous positive shift of 1.84‰ in δ^18O. It is believed that this event is the response of East Asian monsoon climates to ice-rafted events in the northern Atlantic. The comparability between stalagmite δ^18O record and the northern Atlantic deep-sea record indicates that there is a strong climatic tele-connection on millennial-century time scale between the East Asian monsoon and the North Atlantic atmospheric circulations. Our high resolution δ^18O record reveals a striking internal structure of Heinrich event 1, which shows an abrupt rise by - 8.59‰ to - 6. 75‰ within 100 years at initiation and a progressive drop by - 6. 75‰ to - 8.86‰ with 900 years at termination. Such a pattern is similar to Heinrich event 1 （H1） in term of the internal structure, which suggests a similar characteristic for Heinrich events during the Last Glacial Maximum. In this time interval, about half of the Qinghai-Xizang Plateau might be covered by snow and gl

关 键 词：东亚季风 末次盛冰期 Heinrich2事件 石笋 神农架 

分 类 号：P597[天文地球—地球化学]