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Sediment Coring of Lakes in Western and Northern Caucasus as a Basis of Reconstructions - Mikhail Alexandrin - Russia

Tildelt: kr 98 000

The climatic history of the Holocene in Caucasus is very poorly studied. No high resolution climatic and glaciological reconstructions are known up till now. Lacustrine sediments often being a continuous uninterrupted chronicle of sedimentation can be suc cessfully used as a means of specification of glacier situation and age of moraine deposits, as well as a basis for detailed climatic models of the Holocene. The existing reconstructions are primarily based on geomorphic descriptions of moraines and biost ratigraphical data. The available high-resolution reconstructions of the summer temperatures based on tree rings cover only 200 years. The field expeditions of 2010 and 2012 hosted by Institute of Geography, RAS allowed coring the sediment of the four lak es: Lake Karakyol, Bolshoe Dzitakskoe, Bolshoe Khmelevskoe and Lake Donguz-Orun. All the four lakes have different origin and morphology with the latter being a classical periglacial lake dammed by the lateral moraine of Donguz-Orun glacier. Especially no teworthy is thin varved clay of Donguz-Orun sediment core. Preliminary analysis of the sediment cores including grain-size composition, magnetic susceptibility and partial radiocarbon dating reveals the highest priority of the study of the sediment of Cau casus lakes in reconstructions of the history of glaciation and climate of the region. Within the project we will use standard procedures of studying the properties of lake sediments, such as loss-on-ignition, magnetic susceptibility (and correlation of t hese two indexes), x-ray diffraction analyses of the sediment and spectral analysis of the loss-on-ignition data, moisture content and bulk density, advanced analysis of lithological values, the AMS dating for the age control. We will develop the reconstr uction of equilibrium-line altitude variations (TP-ELA) for the Dongus-Orun glacier and, being an ultimate result, create of the first continuous long-term records of climatic parameters of the region.