石笋流体包裹体中的惰性气体及其在重建长江中游古温度变化中的作用  

Noble gases from fluid inclusions of stalagmite and their contribution to reconstructing the variability of paleotemperature in the middle reaches of the Yangtze River,China

作　　者：方念乔[1] 胡超涌[2] 

机构地区：[1]中国地质大学(北京)海洋学院,北京100083 [2]中国地质大学(武汉),湖北武汉430074

出　　处：《地学前缘》2008年第4期132-137,共6页Earth Science Frontiers

基　　金：国家自然科学基金资助项目(40272074)

摘　　要：文中讨论了一种评估古气温变化的新方法。我们成功地利用石笋流体包裹体所捕获的Xe/Ar比值,重建了末次冰盛期以来盛行东亚季风的长江中游地区的气候演化。一种表达成ln(CXe/CAr)的对数式被证明与冷暖周期变化具有密切的关系。从研究的石笋中所提出的δ13C与Mg/Ca曲线一般随区域古气温波动而变化,但不能排除其中有另类气候信号的叠加。我们的工作则明确地指出,流体包裹体所记录的Xe/Ar在各种反映温度变化的替代指标中可能是最好的一种。整体而言,ln(CXe/CAr)曲线与那些基本随暖期和冷期振荡的曲线保持一致。将稀有气体曲线与δ13C和Mg/Ca信号整合对比之后,我们在研究区划分出末次冰盛期以来8组暖/冷旋回。整合后的气温变化模式合理地解释了过去20000年里的区域环境变化。A new method to estimate paleotemperature change is reported in this article. The authors successfully exploit the Xe/Ar ratio trapped in the fluid inclusion of stalagmites for reconstructing climatic evolution since the Last Glacial Maximum （LGM）, in the middle reaches of the Yangtze River, where the East Asian monsoon prevails. A logarithmic expression namely In （CXe/CAr） proves to be bound up with warm/cold cycles. The δ^13C and Mg/Ca curves drawn from the investigated stalagmites mostly follow the fluctuation of regional paleotemperature, but may be overprinted by other climatic signals. This study clearly states that among the diverse proxies, the Xe/Ar ratio recorded in the fluid inclusion is probably the best indicator, constantly mirroring the temperature variation.The In （CXe/CAr） profile on the whole shows an identification with those curves oscillating essentially between the warm and cold phases. After integrating the noble gas profile with the δ3C and Mg/Ca signals, the authors underline eight warm/cold cyclothems developed in the region under study since LGM. The pattern of the climate variation displayed by the integration is reasonable for interpreting the regional environment evolution during the last 20000 years.

关 键 词：惰性气体比值 石笋流体包裹体 古温度 长江中游 过去20 000年 

分 类 号：P593[天文地球—地球化学] P532[天文地球—地质学]