During a collaborative German-Russian helicopter expedition an ecological and limnogeological survey of 14 thermokarst lakes was undertaken along a north-south transect (73°-69°N) along the western side of the lower Lena river (HERZSCHUH et al. 2009). The aim of research project is to reconstruct the Holocene palaeoenvironmental history of north-east Siberia, one of earths most extreme continental climate settings in the northern-hemispheric periglacial realm. Here we present findings from the study of El'gene Kyuele (71°18,04' N, 125°34,15' E), situated in the middle part of the transect, about 50 km north of the present treeline. The lake has a length of 2.9 km and a width of 0.5 km with a maximum water depth >5m. It is built by thermokarst processes of the surrounded deeply loesslike sediments (Yedoma). The elongated shape corresponding to the regional geological structure of the bedrock also indicates a tectonic component influencing the thermokarst lake genesis. The study is devoted to the reconstruction of the depositional palaeoenvironment in a typical thermokarst permafrost setting. What is the sediment source and how much is the thermokarst erosion influencing the sedimento-logical regime? To give an answer to this question geochemical and grain-size studies were conducted on sediment core PG1975-1 retrieved in the central part of the lake using a hammer-modified gravity corer. The core is 136 cm long with a basal age of 6792 ± 30 14C years BP.Downcore elemental composition were obtained by X-Ray Fluorescence Analysis (XRF) using the Avaatech XRF Core Scanner at AWI Bremerhaven. Grain-size has been analysed using a Laser Diffraction Particle Analyser. Additionally smear slides provide qualitative insight into the sediment features suggesting a possibly correlation of grain-size to Sr/Rb ratio. Geostatistical factor analysis of the XRF data reveal Sr/Rb showing a significant proportion of the data variance. In this study we apply Sr/Rb ratio and Zr as grain-size proxies. A significant correlation of Sr/Rb with silty layers (increase) and clayey layers (decrease) is shown in KALUGIN et al. (2007). Input from a possibly loess like sediment source from the northern lakeshore may be represented by Zr. Some intervals within the sediment column are dark-light laminated in a cm scale which can possibly be explained by either increased organic matter input or cyclical sedimentary events. Compared to preliminary age assessments of other lake sediment cores along the transect PG1975-1 shows significant higher sedimen-tation rates and therefore provides potential for high-resolution palaeoenvironmental research.LiteratureHERZSCHUH, U. BOLSHIYANOV, D. PESTRJAKOVA L. BOERSMA, M. ABRAMOVA, K. ZUBRZYCKI, S. BISKABORN, B. KLEMM, J. VAKHRAMEEVA, P. (2009): Ecological state of permafrost lakes and their catchment along a North-South transect in north-central Yakutia: past and present. In: BOIKE, J. ABRAMOVA, K. BOLSHIYANOV, D GRIGORIEV, M. HERZSCHUH, U. KATTNER, G. KNOBLAUCH, C. KUTZBACH, L. MOLLENHAUER, G. SCHNEIDER, W.: Russian-German Cooperation System Laptev Sea: The Expedition Lena 2009. Reports on Polar and Marine Research 600: 22-24.KALUGIN, I. DARYIN, A. SMOLYANINOVA, L. ANDREEV, A. DIEKMANN, B. & KYLYSTOV, O. (2007): 800-yr-long records of annual air temperature and precipitation over southern Siberia inferred from Teletskoye Lake sediments, Quaternary Research 67, 400-410