海洋氧同位素阶段10(Marine Isotope Stages 10,MIS10)气候不稳定,重建这一时段气候变化历史,对于理解末次冰期的千年尺度气候突变和预测未来气候变化具有重要意义.因此,本文利用中国金佛洞石笋J33 230Th测年和氧碳同位素数据,重建了 380～330 ka B.P.(thousand years before present,ka B.P.)时段的古气候序列,旨在探究西南地区东亚夏季风(East Asi-an Summer Monsoon,EASM)以及水文气候环境变化.研究结果显示,在轨道尺度上,MIS10时期的EASM和区域水文环境变化跟随北半球太阳辐射变化,整体上呈现出一峰两谷的形态.MIS10时期气候变化共分为3个阶段:MIS10c冰阶期间EASM相对偏弱,气候冷干;MIS10b间冰阶期间季风相对比较强盛,气候温暖湿润;MIS 10a冰阶期间EASM急剧减弱,气候最为冷干.受太阳辐射缓慢变化引发的大西洋经向翻转环流(Atlantic Meridional Overturning Circulation,AMOC)大幅度振荡的影响,MIS10时期气候不稳定,EASM千年尺度气候突变事件频发,如MIS10b阶段发生了 6次显著的季风增强事件.在冰期终止点Ⅳ(Termination-Ⅳ,T-Ⅳ)结束期间,随着北半球太阳辐射的上升和全球冰量的下降,石笋J33 δ18O记录显示在EASM恢复期间发生了一次与冰期终止点Ⅰ(Termination-Ⅰ,T-Ⅰ)新仙女木事件(Younger Dryas,YD)极其相似的季风减弱事件.类YD事件是最近4个冰消期的普遍特征,而太阳辐射和北大西洋冷事件可能是造成冰消期气候变化错综复杂的主要原因.
Fluctuations of the East Asian Summer Monsoon During MIS 10 Recorded by High-Resolution Stalagmites Samples from Jinfo Cave,Chongqing
By reconstructing the unstable climate history of Marine Isotope Stage 10(MIS10),we can better understand the millennial scale climate change during the Last Glacial Period and in turn have an opportunity to predict future climate change.In this study,we reconstructed the paleoclimatic sequence of the 380-330 ka B.P.period using uranium-thorium dating and oxygen-carbon isotope data from a stalagmite(J33)in the Jinfo Cave of China.The aim was to investigate the impact of the East Asian Summer Monsoon(EASM)and the changes in the hydroclimatic environment in the southwestern region of East Asia.On the orbital scale,EASM and regional hy-droclimates during MIS10 followed fluctuations of solar radiation in the Northern Hemisphere,exhibiting a general pattern of one peak and two troughs.Climate changes during MIS10 can be divided into three stages:during the MIS10c glacial phase,EASM was relative-ly weak,resulting in cold and dry conditions;during the MIS10b interglacial phase,the monsoon was relatively strong,leading to warm and wet climate conditions;during the MIS10a glacial phase,EASM significantly weakened,resulting in the coldest and driest climate.Significant fluctuations of the Atlantic Meridional Overturning Circulation(AMOC),caused by slow variations in solar radia-tion during MIS10,had a major impact on climate instability.Millennial-scale EASM events,such as six significant intensified mon-soon events during MIS10b,were triggered by these solar radiation-induced fluctuations.Stalagmite J33 δ18O revealed a monsoon weak-ening event at the end of Termination-Ⅳ-as levels of Northern Hemispheric solar radiation increased and global ice volume declined-during an EASM recovery period that was highly similar to the Younger Dryas(YD)of Termination-Ⅰ.Events like the Younger Dryas are a common feature of the last four deglaciation periods,and solar radiation and cold events in the North Atlantic may be the primary causes of the complex climate changes during deglaciation periods.
marine Isotope Stages10terminationsthe younger dryas-like eventoxygen and carbon isotopes
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