摘要
研究全新世典型气候突变事件的内部结构及区域特征,有助于明晰季风气候突变事件的成因机制。通过对贵州七星洞石笋14个高精度^(230)Th定年和779个氧同位素数据的分析,重建了过去6380~2700 yr B.P.时段平均分辨率达4.7年的东亚夏季风演化序列。该石笋δ^(18)O值整体上呈逐渐偏正的特征,指示中晚全新世以来东亚夏季风持续变弱的趋势。叠加在此长期季风减弱变化趋势上,最为显著的百年尺度振荡主要发生在4548~3715 yr B.P.时段,对应于4.2 kyr B.P.事件。该记录与同区域董哥洞石笋δ^(18)O记录一致,均显示在此事件内部并非持续干旱,而是具有两次显著的季风强降雨期。相似的季风强降雨期在我国北方气候记录中也有体现。在更大的空间尺度上,这种4.2 kyr B.P.事件的内部结构特征与澳洲—印度尼西亚(澳—印)季风区的石笋记录结构相对应,但呈显著的反相位耦合关系,证实了亚洲与澳—印季风间的动力学联系。此外,该事件结构与ENSO记录的耦合暗示了4.2 kyr B.P.事件的发生可能与热带太平洋密切相关。
Internal structures and regional responses for typical climate events during the Holocene provide important clues to the causes of such events in a warm period.The history of an East Asian summer monsoon evolution was reconstructed for the period 6380-2700 yr B.P.,based on a stalagmite δ^(18)O record in Qixing cave,Guizhou province.This record,with a 4.7-yr average resolution,was established using 14 high-precision ^(230)Th dates and 779 stalagmite oxygen isotope readings.Overall,theδ18O values tend to increase gradually,indicating a continuous weakening of the East Asian summer monsoon during the middle and Late Holocene.Superimposed on this long-term weakening trend is the most significant dry event from 4548 yr B.P.to 3715 yr B.P..This centennial-scale event corresponds to the well-known 4.2 kyr B.P.aridification event.The Qixing δ^(18)O record is consistent with the record from the Dongge cave in the same region,and provides a detailed description of the event.Both records show that the climate was not consistently dry during this period in southwestern China.Two megapluvial episodes were identified during this time,with counterparts in northern China.On a larger-scale spatial extent,the signals within the 4.2 kyr B.P.event are mirrored in stalagmiteδ18O changes in the Australian-Indonesian monsoon region.This antiphase relationship confirms the dynamic links between the Asian and Australian-Indonesian monsoons.In addition,corresponding variation has been discerned between the East Asian monsoon and El Ni?o Southern Oscillation(ENSO)within the 4.2 kyr B.P.event.This correspondence indicates that the 4.2 kyr B.P.event was closely associated with the tropical Pacific Ocean.
作者
张振球
张伟宏
刘树双
翟秀敏
邵庆丰
ZHANG ZhenQiu;ZHANG WeiHong;LIU ShuShuang;ZHAI XiuMin;SHAO QingFeng(School of Geography,Nanjing Normal University,Nanjing 210023,China;School of Life Science,Nanjing Normal University,Nanjing 210023,China;College of Geography and Environment Science,Zhejiang Normal University,Jinhua,Zhejiang 321004,China)
出处
《沉积学报》
CAS
CSCD
北大核心
2023年第1期196-205,共10页
Acta Sedimentologica Sinica
基金
浙江省自然科学基金项目(LY20D020001)
国家自然科学基金项目(42202213)
乐业—凤山世界地质公园开放基金项目(LFD20001)。
