首页> 中文期刊> 《地学前缘》 >黔桂地区最近16万年高分辨率石笋记录的气候事件

黔桂地区最近16万年高分辨率石笋记录的气候事件

         

摘要

Global change is a modern frontier project of earth science. Inorder to predict future climate change and well understand the dynamic process of earth evolution, the high-resolution climate change history of the last two glaciations must be studied and reconstructed. On the basis of sedimentation investigation of several large stalagmites, the high-resolution record of climate change since 160 000a B.P. in Guangxi and Guizhou provinces have been studied using carbon and oxygen stable isotope, αU-series, and TIMS U-series.The records of the climate change from stalagmites since 160 000a B.P. can be correlated with the 1 to 6 stages of that from the ocean. The time of the beginning and ending points of the last glaciation were estimated as(130.1 ±1.0) ka B.P. and (11.2±0.1) ka B.P. The accuracy from the stalagmite record is much higher than that from other record. The results indicates the epochs of Heinrich climate oscillation from stalagmite are H1 14~15 ka B.P., H2 21~23 ka B.P., H3 25~27 ka B.P. and H4 41~42 ka B.P. Furthermore, there was a large cold-event at 35~37 ka B.P. Therefore, the record of last glaciation from stalagmite may well correlate with the record from Greenland ice core.Regarding the existance epochs lagging or surpassing for long-term climate cycle to short-term abrupt climate event, perhaps, these were errors from different test-methods and test-objects (including test-error). If there would be more evidences, the epochs of some climate abrupt events in the global change could be confirmed to be in the same time. The dynamic mechanism of the short-term abrupt event might attribute to the astronomical factors as long-term climate cycle. However, the astronomical factors, which influenced the short-term abrupt climate event, cannot be recognized at present.%全球变化研究是当今地球科学最前沿的课题。要了解地球系统长期演变的动力过程,预测未来气候变化,就必须首先研究和重建最后2次冰期高分辨率的气候变化历史。本项研究选择中国南方广西、贵州地区几个大型石笋,在沉积学研究的基础上,采用碳氧稳定同位素、α谱U系法、TIMSU系(230Th/234U)法等方法提取高分辨率的气候记录。本区16万年来石笋气候记录可以与海洋记录的1~6阶段进行对比。末次冰期的起始点及终止点通过石笋记录分别确定为(130.1±1.0) kaB.P.及(11.2±0.1) kaB.P.,其准确性大大高于目前其它记录。所揭示的Heinrich型气候波动事件,其时限分别为:H114~15kaB.P.,H221~23kaB.P.,H325~27kaB.P.,H441~42kaB.P.,另外在35~37kaB.P.也存在振幅很大的冷事件,与北大西洋沉积及格陵兰冰芯记录可以逐一对比。长周期的气候旋回以及短期的突变事件,在时限上所谓存在几千年以上滞后或超前,可能是测试方法和测试对象的不同带来的差错(包括测试误差);具有全球意义的一些气候突变事件,在发生的时间上可能都具有同时性。这种短期突变事件发生的动力机制问题,可能也是目前人类尚未识别出来的天文因素的驱动所致。

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