Combined application of new proxies (231Pa/230Th and Nd isotopes) to reconstruct the deep ocean overturning over the last 30,000 years.

• Applicant: Dr. Jörg Lippold
• Subject Area: Palaeontology
• Term: from 2010 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 159214802

The Atlantic Meridional Overturning Circulation holds a key role in the climatic system of our planet as it controls the transport of global heat and CO2. In order to estimate or model its future evolution it is crucial to reconstruct the strength of the North Atlantic Deep Water Export in past major climatic transitions such as during the last deglaciation. Regarding the recent stability of the Atlantic circulation the triggers of short-time but extreme cold events during the last termination are of high interest. In contrast to the modern situation, several proxies point to a very different structure of water mass distribution during the Last Glacial. However, there is still no consensus about the variations of the circulation strength or the timing of the major changes. Protactinium, thorium, and neodymium isotopes, extracted from marine sediments, are promising novel proxies to reconstruct the past Deep Ocean hydrography and water mass export. The first time combined application of these tracers on the same sediment samples from the West Atlantic will vitally improve the understanding of both isotopic systems as well as our knowledge about the past Ocean Circulation. Ideally, one proxy will yield information about the rate of overturning circulation, whereas the other proxy carries a water mass provenance signal.

• DFG Programme: Research Grants