Analysis of Sediment Areal Distribution in Laguna Potrok Aike (ASADO)
Zusammenfassung der Projektergebnisse
For palaeolimnological studies long-term trends of palaeoenvironmental variations are mostly interpreted from one single point of a sediment basin. However, only little is known about the spatial variability of sedimentary parameters within lacustrine sedimentary systems and thus about the influence of lake-internal mechanisms on reconstructed climate variables on a spatial scale. Analyses of the spatial sediment distribution in Laguna Potrok Aike were conducted by a dense grid of 63 gravity cores covering the last 700 years to decipher the influence of climatically driven lake internal processes of sedimentation. Previous studies of the maar lake Laguna Potrok Aike document that the variable strengths of the Southern Hemispheric Westerlies (SHW) distinctly influenced hydrological variations during the last millennium. These hydrological fluctuations correspond to lake level changes documented by sub-aerial and sub-aquatic lake level terraces and depositional changes. For a better understanding of how the hydrological variations are transferred spatially to the depositional basin, the aerial sediment distribution was studied for selected late Holocene time slices representing defined lake level high (+) and low (-) stands during the MCA, the LIA and the 20th century warming. The published age-depth model from a site in the deep central basin was transferred to all cores by applying lithological and non-destructive core scanning data. However, this approach does not allow an unequivocal correlation of profundal and littoral cores across the steep slopes of Laguna Potrok Aike. Thus, a correlation of all available 63 gravity cores was only possible for the sediment surface. The correlation of earlier time slices was realized for cores from water depths exceeding 45 m. Multiproxy sediment analyses were conducted on all modern surface sediment samples (-) and on the selected sub-recent time slices of AD 1950 (-), 1800 (+), 1600 (+), 1500 (-) and 1400 (-). Interpretation of distribution patterns strongly depend on the amount of cores used for interpolation. This is related to the reliability and possibility of core correlation and the accuracy of the applied age-depth model. Modern depositional processes provide a detailed picture of the influence of the SHW on shoreline erosion, lake internal currents and sediment transport. The prevailing strong winds cause littoral erosion at all shores, particularly at the eastern shore. Some parameters infer a re-suspension of littoral sediment followed by a redistribution to profundal accumulation areas close to the eastern shore for modern times. For sub-recent time slices differences in lake internal processes between times of high and low lake levels and related variations in SHW intensities were deduced. Distribution patterns reveal intensified sediment redistribution similar to modern times during phases of low lake level and strengthened winds, i.e. during post LIA times (AD 1950) and around AD 1500. In contrast, LIA conditions (AD 1800) with a lake level high stand and less intense westerly winds result in a more homogeneous sediment distribution within the deep central basin. Furthermore, spatial sediment distribution reveals distinct influences of the main western tributary and of the smaller episodic creeks along the eastern shore.
Projektbezogene Publikationen (Auswahl)
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(2007). A continuous 16,000 year sediment record from Laguna Potrok Aike, southern Patagonia (Argentina): Sedimentology, chronology, geochemistry. The Holocene, 17: 297-310
Haberzettl, T., Corbella, H., M. Fey, S. Janssen, A. Lücke, C. Mayr, C. Ohlendorf, F. Schäbitz, G.-H. Schleser, E. Wessel, M. Wille, S. Wulf, B. Zolitschka
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(2008). Hydrological variability and explosive volcanic activity in south-eastern Patagonia during Oxygen Isotope Stage 3 and the Holocene inferred from lake sediments of Laguna Potrok Aike, Argentina. Palaeogeography, Palaeoclimatology, Palaeoecology; 259: 213-229
Haberzettl, T., B. Kück, S. Wulf, F. Anselmetti, D. Ariztegui, C. Corbella, M. Fey, S. Janssen, A. Lücke, C. Mayr, C. Ohlendorf, F. Schäbitz, G. Schleser, M. Wille, B. Zolitschka
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(2009). Environmental history of southern Patagonia unravelled by the seismic stratigraphy of Laguna Potrok Aike. Sedimentology, 56, 873–892
Anselmetti, F., Ariztegui, D., De Batist, M., Gebhardt, C., Haberzettl, T., Niessen, F., Ohlendorf, C., Zolitschka, B.
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(2009). Isotopic and geochemical fingerprints on lacustrine organic matter from Laguna Potrok Aike (southern Patagonia, Argentina) reflect environmental changes during the last 16,000 years. Journal of Paleolimnology 42: 81-102
Mayr, C., A. Lücke, N.I. Maidana, M. Wille, T. Haberzettl, H. Corbella, C. Ohlendorf, F., Schäbitz, M. Fey, S. Janssen and B. Zolitschka
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(2009). Late Pleistocene dust deposition in the Patagonian steppe - extending and refining the paleoenvironmental and tephrochronological record from Laguna Potrok Aike back to 55 ka. Quaternary Science Reviews, 28: 2927-2939
Haberzettl, T., F.S. Anselmetti, S.W. Bowen, M. Fey, C. Mayr, B. Zolitschka, D, Ariztegui, B. Mauz, C. Ohlendorf, S. Kastner, A. Lücke, F. Schäbitz, M. Wille
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(2010). Reconstructing 2000 years of hydrological variation derived from laminated proglacial sediments of Lago del Desierto at the eastern margin of the South Patagonian Ice Field, Argentina. Global and Planetary Change, 72: 201-214
Kastner, S., Ohlendorf , C., Enters, D., Haberzettl, T., Kuhn, G., Lücke, A., Mayr, C., Reyss, J.-L., Wastegård, S., B. Zolitschka
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(2010). Southern Hemispheric Westerlies control spatial distribution of modern sediments (Laguna Potrok Aike, Argentina). Journal of Paleolimnology 44: 887-902
Kastner, S., Ohlendorf, C., Haberzettl, T., Lücke, A., Mayr, C., Maidana, N.I., Schäbitz, F. & Zolitschka, B.
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(2010). Spatial sediment distribution at Laguna Potrok Aike, southern Patagonia, Argentina – An areal sediment survey to analyse the influence of late Holocene climate variability on sediment characteristics. Terra Nostra, 2010/1: 31-34
Kastner, S., Ohlendorf, C., Haberzettl, T., Lücke, A., Mayr, C., Maidana, N.I., Schäbitz, F. & B. Zolitschka
