Dansgaard/Oeschger Events During Marine Isotope Stage 8

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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.