Paleoclimate Record since the Last Glacial from the Southern Hemisphere – ICDP Deep Drilling at Laguna Potrok Aike, Argentina.

ZOLITSCHKA, B., F.ANSELMETTI, D.ARIZTEGUI, H.CORBELLA, P.FRANCUS, C.GEBHARDT, A.HAHN, P.KLIEM, A.LÜCKE, C.OHLENDORF, F.SCHÄBITZ, R.PIENITZ, AND THE PASADO SCIENCE TEAM

Guadalajara, Jalisco, Mexico

Simposio; 11th International Paleolimnology Symposium; 2009

International Paleolimnology Association

Paleoclimate Record since the Last Glacial from the Southern Hemisphere – ICDP Deep Drilling at Laguna Potrok Aike, Argentina   Bernd Zolitschka1, Flavio Anselmetti2, Daniel Ariztegui3, Hugo Corbella4, Pierre Francus5, Catalina Gebhardt6, Annette Hahn1, Pierre Kliem1, Andreas Lücke7, Christian Ohlendorf1, Frank Schäbitz8, Reinhard Pienitz9, and the PASADO science team   1 Geopolar, Institute of Geography, University of Bremen, Germany (zoli@uni-bremen.de) 2 Eawag, Swiss Federal Institute of Aquatic Science & Technology, Dübendorf, Switzerland 3 Section of Earth and Environmental Sciences, University of Geneva, Switzerland 4 Argentine Museum of Natural History, Buenos Aires, Argentina 5 Institut National de la Recherche Scientifique (INRS), Québec, Canada 6 Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany 7 ICG 4, Energy & Environment, Research Center Jülich, Germany 8 Seminar for Geography and Education, University of Cologne, Germany 9 Département de Géographie & Centre d'études nordiques, Université Laval, Québec, Canada (Reinhard.Pienitz@ffgg.ulaval.ca)   Laguna Potrok Aike, located in the South-Patagonian province of Santa Cruz (52°58’S, 70°23’W), was formed 770 ka ago by a volcanic (maar) eruption. Within the framework of the ICDP-funded project PASADO two sites were drilled in 2008 using the GLAD800 drilling platform. A total of 513 m of sediments were recovered from the deep central basin by an international team. The sediments hold a unique record of paleoclimatic and paleoecological variability from a region sensitive to variations in southern hemispheric wind and pressure systems and thus are significant for the understanding of the global climate system. Moreover, Laguna Potrok Aike is close to active volcanoes allowing a better understanding of the history of volcanism in the Pali Aike Volcanic Field and in the nearby Andean mountain chain. These challenging scientific themes need to be tackled in a global context as both are of increasing socio-economic relevance. On-site core logging based on magnetic susceptibility data documents an excellent correlation between all holes from both drilled sites. After splitting of cores in the laboratory, a reference profile was established down to a composite depth of 107 m for the triplicate cores from Site 2. Sediments consist of laminated and sand-layered lacustrine silts with an increasing number of turbidites and homogenites with depth. Below 80 m composite depth two mass movement deposits (10 m and 5 m in thickness) are recorded. These deposits show tilted and distorted layers as well as nodules of fine grained sediments and randomly distributed gravel. Such features indicate an increased slump activity probably related to lake level fluctuations or seismicity. Also with depth coarse gravel layers are present and point to changes in hydrological conditions in the catchment area. Intercalated throughout the record are 24 macroscopic volcanic ash layers that document the regional volcanic history and open the possibility to establish an independent time control through tephrochronology. These isochrones potentially act as links to marine sediment records from the South Atlantic and to Antarctic ice cores. Preliminary interpretation of all available data and extrapolation of sedimentation rates determined for the upper 16 ka indicate that the record may go back in time to oxygen isotope stage 5a and covers approximately the last 80 ka.