【作者】 王鹏；

【导师】 张平中；

【作者基本信息】 兰州大学 ， 地质学·地球化学， 2022， 硕士

【摘要】 随着社会的发展和工业化的推进,全球变暖已经成为全人类必须面对的问题,地球温室效应加剧、极端气候事件频发,严重影响着人们的生存与发展。目前正处于现代间冰期,探讨过去几次间冰期气候的变化及影响因素是预测未来气候变化的基础。末次间冰期包含了与现在相似的暖期气候变化信息,然而对末次间冰期气候变化的特征和影响还没有达成共识。本文将时间扩展至倒数第二次冰消期,探究冰期-间冰期气候变迁模式、影响因素。冰期-间冰期之间的循环主要是受到太阳活动的驱动,而内部千年尺度的气候波动则是受到地球内部作用的影响。东亚夏季风（EASM）在全球大气热力学中起着重要作用,相关的降水量直接影响着世界上人口最稠密地区东亚的社会经济发展,我国大部分地区都受到亚洲夏季风的影响,季风带来的降水也会影响农业发展和社会稳定。洞穴石笋由于定年准确、分辨率高、分布广泛、连续沉积等优点,被广泛用于古气候的重建,对洞穴石笋δ¹⁸O指标的不断研究,大大拓宽了我们对亚洲季风从轨道尺度到年代际变化的认识。本文利用亚洲夏季风边缘区武都万象洞石笋WXZ05-12的3个U-Th年代数据和644个δ¹⁸O、δ¹³C稳定同位素记录,重建了132.9ka B.P.-126.9ka B.P.（MIS6-5e）期高分辨率、高精度的亚洲夏季风千年-百年尺度的变迁序列。通过研究,最终得出亚洲夏季风的演化规律及影响因素:1.通过与中国北方的上晓峰洞、葫芦洞、兴隆洞以及南方的三宝洞、董哥洞、羊口洞和小白龙洞石笋进行对比,发现亚洲季风中国区的石笋δ¹⁸O在这一时期的变化具有良好的一致性,在千年-百年尺度上存在季风波动的重现性,说明万象洞石笋WXZ05-12是该时期亚洲夏季风变迁的可靠指标。碳氧同位素在千年-百年尺度上呈现出高度的正相关性,即碳、氧同位素在千年-百年尺度上强耦合,表明在MIS 6-5e期碳、氧同位素能共同反映亚洲夏季风的变迁。2.将万象洞石笋δ¹⁸O记录与北半球不同纬度地区的气候替代指标数据进行对比发现,在整个MIS 6-5e期间,亚洲夏季风的千年-百年尺度季风事件在北半球高、中、低纬度的气候指标中均有响应,说明北半球高、中、低纬度的气候事件在千年-百年尺度的遥相关关系依然存在。此外,将万象洞石笋与南半球不同纬度的气候记录对比,季风波动事件在南半球的气候记录中也都能找到与之相匹配的反相位的气候事件,说明在千年-百年时间尺度上,南北半球的气候的“跷跷板”效应依旧存在。3.对石笋碳氧同位素进行功率谱分析发现MIS 6-5e期亚洲季风主要受控于太阳活动的驱动,将万象洞石笋δ¹⁸O与北大西洋冰筏碎屑事件、南极洲温度、北半球温度以及ITCZ位置的对比,发现在倒数第二次冰消期与末次间冰期的过渡时期,随着北半球夏季太阳辐射的增强,亚洲夏季风也随之增强。千年-百年尺度上的气候波动主要受到ITCZ的影响,ITCZ偏北时亚洲季风强度增强,反之亦然。同时ITCZ影响区域的亚洲季风区中国石笋洞穴石笋δ¹⁸O值在倒数第二次冰消期和末次间冰期过渡期时发生突变,而没有受到ITCZ影响的北方洞穴石笋δ¹⁸O则表现为渐变。北半球夏季太阳辐射增强导致的北大西洋海冰融化,冰筏碎屑增多,大量淡水注入使AMOC活动的强度降低,大洋循环和大气循环发生变化进而影响亚洲夏季风强度;南半球的气候变化通过影响全球范围内的大气和大洋环流在一定程度上对亚洲夏季风强度产生影响,海因里希事件11开始阶段AMOC活动减弱,西风带和ITCZ南移,亚洲季风减弱,反之亦然。更多还原

【Abstract】 With the development of society and the advancement of industrialization,global warming has become a problem that all mankind must face,global warming effect is increase and extreme climate events is frequently occurred,which seriously threaten human survival and development.Nowadays,It is currently in the modern interglacial period,discussing the changes and influencing factors of the climate during the past interglacials is the basis for predicting future climate change.The last interglacial contains information about how Climate change during a warm period like the current intervals,However,there is no consensus on the signatures and influence of last interglacial.There we extend the time serious to TerminationⅡto explore the changes and forcing in glacial-interglacial cycles.and the conditions of a series of sudden changes in climate of centennial-millennial scale.The glacial-interglacial cycles during was mainly driven by solar activities.Millennium scale climate fluctuations are affected by the internal effects of the earth.The East Asian Summer Monsoon（EASM）plays an important role in the global atmospheric thermodynamics,and the related precipitation directly affects the socio-economic development of East Asia,the most densely populated region in the world.Cave stalagmites are widely used in the reconstruction of the ancient climate due to the advantages of accurate dating,high resolution,wide distribution,and continuous deposition.The continuous research on cave stalagmitesδ¹⁸O has greatly broadened our Understanding the Asian monsoon from orbital scale to interdecadal change.In this paper,three U-Th dating data and 644δ¹⁸O andδ¹³C stable isotope records of the stalagmite WXZ05-12 in the Wanxiang cave,which at the edge of the Asian summer monsoon region are used to reconstruct high-resolution and high-precision data from132.9ka B.P.to 126.9ka B.P.sequence of the Asian summer monsoon on the millennium-centennial scale.1.Comparing our stalagmite from Wanxiang cave with the stalagmites of Hulu Cave,Xinglong Cave in northern China,and Sanbao Cave,Dongge Cave,and Yangkou Cave in the south,it was found that the stalagmiteδ¹⁸O in the Chinese region of Asian monsoon had a good correlation during this period,and the reproducibility of monsoon fluctuations on the millennium-century scale indicates that the stalagmite WXZ05-12in Wanxiang Cave is a reliable indicator of the change of the Asian summer monsoon during this period.δ¹⁸O andδ¹³C isotope data show a high positive correlation on the millennium-centennial scale,that is,δ¹⁸O andδ¹³C isotope data are strongly coupled on the millennium-centennial scale,indicating that the carbon and oxygen isotopes are together reflect the changes of the Asian summer monsoon during the penultimate glacial period.2.Comparing the stalagmiteδ¹⁸O record of the Wanxiang cave with the climate substitution index data of different latitudes in the northern hemisphere,it was found that the millennial-century monsoon event of the Asian summer monsoon in the entire TerminationⅡerosion period was in the high,medium and low climate of the northern hemisphere.These responses in the indicators,shows that the climatic events of high,middle and low latitudes in the northern hemisphere still exist in the millennium-century scale.In addition,comparing the stalagmites of Wanxiang Cave with the climate records of different latitudes in the southern hemisphere,monsoon fluctuation events can also be found in the southern hemisphere’s climate records to match the anti-phase climate events,indicating that on the millennium-century time scale,“The see-saw effect”of the climate in the northern hemisphere and the southern hemisphere is still exists.3.We find that MIS 6-5e ASM intensity was driven by solar intensity by using the Power spectrum analysis of WXZ 5-12δ¹⁸O andδ¹³C time series.Comparing the stalagmiteδ¹⁸O in the Wanxiang cave with the North Atlantic ice raft debris（IRD）event,Antarctica temperature,northern hemisphere temperature and ITCZ location,it was found that during TerminationⅡthe intensity of the Asian summer monsoon on the orbit-millennium scale is still mainly controlled by the intensity of solar radiation,but the climate fluctuations on the millennium-century scale is mainly affected by location ITCZ.When ITCZ is northerly,the intensity of the Asian monsoon increases,and vice versa.At the same time,the stalagmiteδ¹⁸O value of the Chinese stalagmite cave in the Asian monsoon area affected by the ITCZ was abruptly changed during the penultimate glacial period and the last interglacial transition period,while the northern cave stalagmiteδ¹⁸O that was not affected by the ITCZ shows a gradual change.The increase in the North Atlantic sea ice affects the intensity of AMOC activity,causing ITCZ move northward,and the ocean cycle and atmospheric cycle change to affect the intensity of the Asian summer monsoon.Climate change in the southern hemisphere affects the intensity of the Asian summer monsoon to a certain extent by affecting the global atmosphere and ocean circulation.AMOC activity declines at the beginning of the H11 event,the Westerlises and ITCZ move south,the Asian monsoon weakens,and vice versa.更多还原