Genty D, Blamart D, Ouahdi R, Gilmour M, Baker A, Jouzel J, Van-Exter Sandra
IPSL/Laboratoire des Sciences du Climat et de l'Environnement, UMR CEA/CNRS 1572 Bat. 709, L'Orme des Merisiers CEA Saclay, 91191 Gif sur Yvette cedex, France.
Nature. 2003 Feb 20;421(6925):833-7. doi: 10.1038/nature01391.
The signature of Dansgaard-Oeschger events--millennial-scale abrupt climate oscillations during the last glacial period--is well established in ice cores and marine records. But the effects of such events in continental settings are not as clear, and their absolute chronology is uncertain beyond the limit of (14)C dating and annual layer counting for marine records and ice cores, respectively. Here we present carbon and oxygen isotope records from a stalagmite collected in southwest France which have been precisely dated using 234U/230Th ratios. We find rapid climate oscillations coincident with the established Dansgaard-Oeschger events between 83,000 and 32,000 years ago in both isotope records. The oxygen isotope signature is similar to a record from Soreq cave, Israel, and deep-sea records, indicating the large spatial scale of the climate oscillations. The signal in the carbon isotopes gives evidence of drastic and rapid vegetation changes in western Europe, an important site in human cultural evolution. We also find evidence for a long phase of extremely cold climate in southwest France between 61.2 +/- 0.6 and 67.4 +/- 0.9 kyr ago.
末次冰期期间千年尺度的丹斯加德-厄施格尔事件(Dansgaard-Oeschger events)——即突然的气候振荡——在冰芯和海洋记录中已得到充分证实。但此类事件在大陆环境中的影响并不那么清晰,而且在超出海洋记录和冰芯分别对应的碳-14测年和年层计数的极限后,其绝对年代学并不确定。在此,我们展示了来自法国西南部采集的一根石笋的碳和氧同位素记录,这些记录已利用234U/230Th比率精确测定年代。我们在两条同位素记录中均发现,在83,000至32,000年前,快速的气候振荡与已确定的丹斯加德-厄施格尔事件同时出现。氧同位素特征与以色列索雷克洞穴(Soreq cave)的记录以及深海记录相似,这表明气候振荡具有较大的空间尺度。碳同位素信号证明了西欧植被的剧烈和快速变化,而西欧是人类文化演化的一个重要地点。我们还发现了法国西南部在距今61.2±0.6至67.4±0.9千年前存在极冷气候的长期阶段的证据。