重庆羊口洞石笋记录的Heinrich事件

发布时间：2018-06-08 14:14

本文选题：重庆羊口洞 + δ~(18)O　；参考：《西南大学》2015年硕士论文

【摘要】：全球变暖问题己成为全球关注的焦点。全球气候变化不再仅仅是一个学科问题,而日渐成为当今人类社会最为关注的重大社会问题,与人类的生存环境密切相关。末次冰期最典型的气候变化特征是一系列百年-千年尺度的气候波动,即Heinrich (H)事件和Dansgaard-Oeschger (D/O)循环。目前由于缺乏高分辨率、精确定年的地质记录,关于一系列H事件的起止和持续时间以及内部结构等特征还存在争议,其气候驱动机制也尚未被完全认识清楚。相对于黄土、冰芯、湖泊等记录,洞穴石笋具有高分辨率、精确定年、记录气候和环境信息完整等优势,已成为当前相关研究领域的重要载体之一。本文以重庆金佛山羊口洞YK1和JFYK7石笋为研究对象,利用高精度的230Th测年技术以及氧稳定同位素记录,建立了该地区末次冰期高分辨率的古气候变化时间序列,并与全球其它地质记录进行对比,利用RAMPFIT拟合方法对H1-H6事件进行了标定,并分析了其与其它地质记录所记录的H事件起止时间的相位差,以及内部结构的异同。进而探讨亚洲季风环流格局,以及与格陵兰地区和南极地区温度变化的关系。通过分析羊口洞石笋YK1和JFYK7高分辨率的δ18O记录,发现YK1和JFYK7石笋符合Hendy检验标准,且两者具有很好的重现性,因此可以利用石笋YK1和JFYK7的氧稳定同位素记录进行古气候重建。通过对比,证明了羊口洞石笋记录的H事件与其它地质记录的吻合性,说明羊口洞石笋能反映当时的气候变化,共同受控于亚洲夏季风的变化,在H事件发生期间,亚洲夏季风减弱,石笋δ18O明显偏重。在长时间尺度上太阳辐射曲线与石笋δ18O变化有很好的对应关系,但在一些短时间尺度的变化上二者并没有很好的对应关系。可能是因为石笋δ18O的影响因素除太阳辐射外,还有很多其它因素,主要有温度、降水量和蒸发量、冬夏降水量比值、水汽来源和大气环流等。利用重庆羊口洞石笋YKl和JFYK7以及其它地区地质记录的氧同位素数据,通过RAMPFIT方法进行拟合,标定了Heinrich事件的起止时间,并通过全球对比分析了其内部结构变化特征。与同处在亚洲季风区的新崖洞、小白龙洞、董哥洞、葫芦洞、三宝洞记录对比表明,亚洲季风区千年尺度大气降水氧同位素组成变化在大范围上具有空间一致性。但是羊口洞石笋具有更准确的年龄和更高的分辨率,使得H事件的标定更为可靠。H1-H6事件在东亚季风区的石笋中的记录,反映的是夏季风减弱,与北大西洋格陵兰冰芯中记录的温度降低相对应。此外印度季风区的石笋中也记录了此类事件,同样代表夏季风强度减弱。而南半球的石笋氧同位素则与亚洲石笋相反,即在H事件期间,南半球夏季风和西风强度增强,与南极冰芯记录的温度升高相吻合。这也说明了南北半球气候变化在千年尺度上的反相位关系。但是各地质记录的变化模式并不是完全一致的,反映了地域差异。亚洲季风区石笋记录H2、H3以及H4事件的变化模式与南极冰芯EDML温度记录的变化模式相似,说明末次冰期时东亚夏季风除了能反映北半球高纬度地区的信号外,还会受到南半球温度变化的影响。北大西洋经向环流(AMOC)是亚洲冬夏季风气候突变的主要原因,北高纬的气候信号主要通过西风带来影响到亚洲夏季风的强弱,进而影响到石笋氧同位素和黄土中值粒径的变化。北大西洋地区的气候和亚洲季风遥相关,是因为太阳辐射减弱时,格陵兰地区的温度降低,海陆热力差异减小,导致亚洲夏季风减弱。H事件发生期间,西伯利亚高压增强,北半球温度降低,此时热带辐合带(ITCZ)向南移动,导致亚洲冬季风增强且持续时间增长,而夏季风环流减弱。ITCZ的南北移动是由南北半球的温度梯度引起的,ITCZ趋向更暖的半球。ITCZ的南北移动与北大西洋经向环流(AMOC)有关,AMOC减弱,由此导致海洋向北传输的热量减少,海表温度降低,北半球变冷,ITCZ向南移动。
[Abstract]:Global warming has become the focus of global concern. Global climate change is no longer a subject matter, but is increasingly becoming the most important social problem in human society today. It is closely related to the living environment of human beings. The most typical climate change in the last glacial period is a series of century - Millennium scale climate fluctuations, that is, He The inrich (H) event and the Dansgaard-Oeschger (D/O) cycle. Currently, due to the lack of high resolution, precise annual geological records, the beginning and end time and internal structure of a series of H events are still controversial, and its climate driving mechanism has not yet been fully recognized. The bamboo shoots have the advantages of high resolution, accurate dating, record the integrity of climate and environmental information, and have become one of the important carriers in the current research field. This paper takes the YK1 and JFYK7 stalagmite of Jinfu goats in Chongqing as the research object. The high precision 230Th dating technique and the oxygen stable isotope record have been used to establish the high end glacial period in this area. The resolution of paleoclimate change time series is compared with other geological records in the world. The RAMPFIT fitting method is used to calibrate the H1-H6 event, and the difference between the phase difference and the internal structure of the H events recorded by the other geological records is analyzed, and the Asian monsoon circulation pattern is discussed, and the Geo mausoleum is also discussed. The relationship between the temperature changes in the orchid area and the Antarctic region. Through the analysis of the YK1 and JFYK7 high-resolution Delta 18O records of the goat mouth cave, it was found that the YK1 and JFYK7 stalagmite were in conformity with the Hendy test standard, and both had good reproducibility. Therefore, the oxygen stable isotopic records of the stalagmite YK1 and JFYK7 could be used to reconstruct the paleoclimate. The H events recorded in the sheep cave stalagmites coincide with the other geological records, indicating that the Asiatic stalagmite can reflect the climate change at that time, which is controlled by the changes in the Asian summer monsoon. During the H event, the Asian summer monsoon weakened and the stalagmite Delta 18O was significantly heavier. On a long time scale, the solar radiation curve and the stalagmite Delta 18O were very good. The corresponding relationship, but there is not a good correspondence between the two of the short time scales, maybe because of the influence factors of the stalagmite Delta 18O except for the solar radiation, there are many other factors, mainly temperature, precipitation and evaporation, the ratio of winter and summer precipitation, the source of water vapor and the circulation of the atmosphere, and the use of Chongqing's oromouth cave of YKl and J FYK7 and the oxygen isotope data of geological records in other regions are fitted by RAMPFIT method to calibrate the beginning and stop time of Heinrich events and to analyze the characteristics of their internal structure changes through global comparison. The records of the new cliff cave in the Asian monsoon region, the small white Dragon Cave, Dong Ge cave, the gourd cave and the three treasure cave show that the Asian monsoon The variation of the oxygen isotope composition of the atmospheric precipitation in the Millennium scale has spatial consistency in a large range. But the goat mouth cave stalagmites have more accurate age and higher resolution, making the calibration of the H event more reliable.H1-H6 events in the stalagmite of the East Asian monsoon region, reflecting the weakening of the summer monsoon and the Greenland ice core in the North Atlantic. In addition, this kind of event is also recorded in the India monsoon area, which also indicates that the intensity of the summer wind is weakened. The oxygen isotope of the southern hemisphere is contrary to the Asian stalagmite, that is, during the H event, the summer monsoon and the westerly intensity in the southern hemisphere are enhanced, which is also consistent with the increase in the temperature of the Antarctic ice core. The anti phase relation of climate change on the Millennium scale in the northern and southern hemisphere is clear, but the variation patterns of the geological records are not completely consistent, reflecting regional differences. The variation patterns of H2, H3 and H4 events in the Asian monsoon region are similar to that of the EDML temperature records in the Antarctic ice core, indicating the East Asian summer in the last glacial period. The North Atlantic meridional circulation (AMOC) is the main reason for the abrupt change in the winter and summer climate in Asia. The climate signals of the northern high latitude are mainly influenced by the westerly wind to influence the Asian summer monsoon and the oxygen isotope and yellow of the stalagmite. The climate of the North Atlantic region and the Asian monsoon teleconnection are due to the decrease in the temperature of the Greenland and the decrease of the thermodynamic differences in the Greenland region when the solar radiation is weakened, resulting in the weakening of the Asian summer monsoon during the.H event, the increase in the high pressure in Siberia, the lower temperature of the north half of the ball, and the southward movement of the tropical convergence zone (ITCZ) at this time. The Asian winter winds increased and continued to increase, while the summer monsoon circulation weakened the North-South movement of.ITCZ, which was caused by the temperature gradient in the northern and southern hemispheres. ITCZ tends to be related to the North-South movement of the warmer hemisphere and the North Atlantic meridional circulation (AMOC), and the AMOC is weakened, thus reducing the heat transfer to the north of the ocean and reducing the temperature of the sea surface, and the temperature of the sea surface is reduced. The northern hemisphere is colder, and ITCZ moves southward.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P532

【参考文献】