The maar lake Laguna Potrok Aike is located in the semi-arid Patagonian steppe (52°S), an area with hitherto only scarce paleoenvironmental information. Within the project SALSA (South Argentinean Lake Sediment Archives and modeling) Laguna Potrok Aike turned out to be the key site for recording climatic events in that area. With a continuous, high-resolution multi-proxy approach applied to the radiocarbon, optical (OSL) and tephra-dated sediments it is possible to distinguish between high and low lake level stands. Hydrological variations seem to be linked to variations in the carbonate content of Laguna Potrok Aike sediments brought about by concentration and dilution processes which was confirmed by various other proxies of lake level changes. These variations not only give information about climate events like the Little Ice Age or the Medieval Climate Anomaly, but also reflect rapid hydrological variations in southern Patagonia during the past 16 ka. Recently, the record was extended to the past 55 ka and suggests a high lake level for Laguna Potrok Aike before 13.1 cal ka BP. Variations in grain size and comparison of magnetic susceptibility, an assumed dust proxy, at Laguna Potrok Aike with the non-sea-salt calcium flux at Dome C (Antarctica) indicate a relatively high aeolian input during the glacial period. Although the source of the dust found in Antarctic ice cores often has been attributed to Patagonia, this is the first evidence for a similar dust pattern for both the main source area of southern South America and Antarctica. Additionally, analyses of volcanic ashes revealed that Laguna Potrok Aike is perfectly suited to extend the southern South American tephra chronology. Up to now, already three formerly unknown volcanic ashes were recovered from the sediment cores and tentatively dated to Oxygen Isotope Stage 3. These three examples demonstrate the potential for future research on sediment cores from Laguna Potrok Aike recovered during the ICDP drilling project PASADO (Potrok Aike maar lake sediment archive drilling project) probably reaching back to Oxygen Isotope Stage 5. PASADO not only enables a temporal extension of the existing record but also allows for higher-resolution analyses, as previously existing sediment cores exceeding 13.1 ka were recovered from very condensed sequences from the steep flanks of the lake. In addition to that, the international co-operations permit the utilization of a larger set of methods such as rock- and paleomagnetic-, biomarker-, or deep biosphere studies.
Helmholtz Research Programs > PACES I (2009-2013) > TOPIC 3: Lessons from the Past > WP 3.2: Tectonic, Climate and Biosphere Development from Greenhouse to Icehouse