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Paleomagnetic applications for dating and identifying Holocene climate variability in southwestern Europe and Azores Islands as recorded by lake sediments (PALEOCLAK)
Date du début: 1 mars 2013, Date de fin: 31 août 2015 PROJET  TERMINÉ 

"Over the last years, a strong multidisciplinary effort is being done by several Spanish research groups in order to recover pristine sediment cores from lakes at different biogeographic provinces throughout the Iberian Peninsula and Azores Islands. The lacustrine sequences recovered constitute an irreplaceable record of past environmental and climatic changes. The paleomagnetic and environmental magnetic techniques represent porwerful tools for dating and identifying Holocene climate variability as recorded by these lacustrine sediments. However, up to now nobody had considered applying systematically these techniques to the material recovered. PALEOCLAK proposes a work plan to carry out this research in Géosciences-Rennes. A preliminary study (one core per site) of cores from 17 different lakes covering the Holocene will be carried out in order to obtain a general view of their paleomagnetic behavior. The results will be used to identify and select the most promising recorders of past geomagnetic field and environmental changes. Several cores per selected site will be studied. The results will produce: 1) new Holocene paleosecular and relative paleointensity curves (derived from well-dated cores). These curves will provide a new tool for dating Holocene sedimentary sequences from these regions; and 2) a catalogue of environmental magnetic data from lakes with different origins and climatic contexts. This catalogue will be used to identify paleoenvironmental variations as recorded by changes in the type, concentration and grain size of magnetic minerals. By comparing the rock-magnetic data with available sedimentological, geochemical and biological proxies, we will be able to disentangle the specific processes that modulate the magnetic signal. Finally, the paleomagnetic dating technique will be used for establishing accurate high-resolution age models in which the paleoenvironmental response to climatic and anthropogenic impacts can be properly evaluated."

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