Climatic and environmental changes during Marine Isotope Stages 3, 2 and 1 in southern Patagonia : Evidences from Laguna Potrok Aike (Argentina)
|Other Titles:||Klima- und Umweltveränderungen während der Marinen Isotopenstadien 3, 2, und 1 im südlichen Patagonien : Belege von der Laguna Potrok Aike (Argentinien)||Authors:||Kliem, Pierre||Supervisor:||Zolitschka, Bernd||1. Expert:||Zolitschka, Bernd||2. Expert:||Haberzettl, Torsten||Abstract:||
Since the year 2001 paleolimnological studies at the maar Laguna Potrok Aike (LPA) in southern Patagonia extend our knowledge about the past regional environment conditions and about the climatically important southern hemispheric westerlies (SHW). In the frame of the ICDP (International Continental Scientific Drilling Program) project PASADO (Potrok Aike Maar Lake Sediment Archive Drilling Project) the paleolimnological research at LPA intensi-fied in 2008. After positive experiences of previous projects different research disciplines were brought together in a multi-proxy approach. The data basis was established by extensive drilling on lake sediments and field work in the catchment of the lake. The focus was represented by about 100 m deep core drillings in the lake sediment. The lithological, chronological and frequency analytical examination of the 106.09 m long composite profile 5022-2CP drilled in the southern profundal of the lake was the focus of this PhD thesis. Furthermore, results of geomorphological and sedimentological field work in the realm of the lake surrounding basin as well as in the proximate catchment were analyzed. Pelagic deposits, lake internal mass movements and tephra were identified at composite profile 5022-2CP. Striking, the amount of lake internal mass movements represented more than 50 % of the composite profile. The with lower core depths reducing ratio of mass movement deposits was interpreted as decreasing relief energy, slope consolidation and a less inclined slope angle during proceeding sediment filling of the basin. Furthermore, the intensity of lake level changes might have enforced the collapse of slopes which increased the amount of mass movement deposits. Regarding structure and compounds pelagic sediments deposited during the interglacial times distinctly differentiate from sediments deposited during glacial times. Laminated silt with carbonate crystals dominated in Holocene sediments. Laminated silt with intercalations of fine sand and coarse silt dominated in sediments of the glacial period. Lake internal mass movements and tephra layers were the only hiatus in the continuous sedimentary sequence. After radiocarbon-based age-depths-modeling 5022-2CP represents the time window of the past ca. 51.200 years. Based on sedimentary, seismic and geomorphological evidences the magnitude, geomorphological response and climate links of LPA lake level oscillation were examined. Five distinct major treads between 136 and 85 m a.s.l were identified and reflect abrasion and lake level oscillations of at least the past 51.200 years. This process expanded the lake basin from originally 2.2 km to 3.8 km.
|Keywords:||lake level fluctuations; Late Pleistocene; Holocene; Patagonia; Argentina; ICDP-project PASADO; Southern Hemispheric Westerlies; permafrost; Frequency analysis; Bond cycles; Dansgaard-Oeschger events||Issue Date:||4-Nov-2019||DOI:||10.26092/elib/304||URN:||urn:nbn:de:gbv:46-00108618-14||Institution:||Universität Bremen||Faculty:||FB08 Sozialwissenschaften|
|Appears in Collections:||Dissertationen|
checked on Oct 20, 2020
checked on Oct 20, 2020
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