Dansgaard/Oeschger Events During Marine Isotope Stage 8

在这个项目中，将确定倒数第二次冰川之前(距今约30万年至23万年)的Dansgaard/Oeschger事件，并将准确确定每一事件的开始和持续时间。Dansgaard/Oeschger事件是最后一次冰川期间短暂且重复的温暖事件，似乎遵循一定的周期性。最初，它们是通过格陵兰岛上钻探的冰芯稳定氧同位素组成的快速变化而被观察到的。它们似乎在北半球大部分地区的各种气候档案中留下了它们发生的迹象。例如，他们的指纹也在过去20万年来欧洲阿尔卑斯山北缘洞穴沉积物的稳定氧同位素组成中被观察到。然而，目前还没有关于倒数第二次冰川前的丹斯加德/欧施格事件的大陆信息。格陵兰岛的冰芯不覆盖这段时间间隔，因为没有这种年龄的冰可用。这一时期的海洋沉积物在其替代物中清楚地显示出Dansgaard/Oeschger式的模式-然而，从这个档案中很难获得准确的年代学。对于这个项目，我们从阿尔卑斯山北部找到了八个石笋，它们生长在倒数第二次冰川之前。在很长的时间间隔内，它们成对地同时生长，因此获得了高度的重复性。稳定的氧同位素分析将为这些快速气候变化的存在提供强有力的证据，铀-钍方法将被用来建立精确的年代学。因此，这一方法有助于改进我们对倒数第二次冰期前的气候变化年表的了解，并将有助于理解它们对北半球气候的影响、它们的周期性和触发机制。

In this project, Dansgaard/Oeschger events in the ante penultimate glacial, between ~300 000 to 230 000 years before present, will be identified and the beginning and the duration of each event will be precisely determined. Dansgaard/Oeschger events are short-lasting and repeating warm episodes during the last glacial and seem to follow a certain cyclicity. Originally, they were first observed by fast variations in the stable oxygen isotope composition of ice cores drilled on Greenland. They seem to left hints of their occurrence in various climate archives over large parts of the northern hemisphere. Their finger prints, for example, were also observed in the stable oxygen isotope composition of speleothems from the northern rim of the European Alps over the last 200 000 years. However, currently there is no continental information about the Dansgaard/Oeschger events during the ante penultimate glacial available. Greenland’s ice cores do not cover this time interval since no ice of such age is available. Marine sediments clearly show Dansgaard/Oeschger like pattern in their proxies in this period - however a precise chronology is difficult to obtain from this archive. For this project we have eight stalagmites from the northern Alps which grew during the ante penultimate glacial. Over large time intervals pairs of them grew contemporaneously, so that a high degree of reproducibility is granted. Stable oxygen isotope analyses will provide strong evidence for the existence of these fast climate variations and the uranium-thorium method will be used to establish a precise chronology. Thus, this approach is able to contribute significantly to improve our knowledge of the chronology of these climate variations during the ante penultimate glacial and will help to understand their impacts on climate in the northern hemisphere, their cyclicity and triggering mechanism.