Orbital variability and high latitude circulation and climate change during the Pliocene-Pleistocene.
Zusammenfassung der Projektergebnisse
The main goal of this study was to improve the record of changes in ocean circulation in the climatically relevant key areas of the Nordic Seas and North Atlantic Ocean and their relationships to glaciations controlling and responding to climate. To investigate past water mass mixing and erosional input, the radiogenic isotope signatures of neodymium (Nd), lead (Pb) and strontium (Sr) of seawater-derived ferromanganese coatings on sediment particles, as well as of detrital material were analyzed. Sediments obtained from six ODP (Ocean Drilling Program) Sites (Site 984, 907, 911, 986, 644, 982) covering intermediate to deep waters in the Nordic Seas and North Atlantic Ocean were the basis of this study. Tests revealed that only for Sites 982, 644, 986, and 911 in the eastern part of the Nordic Seas and in the North Atlantic Ocean reliable past bottom water signatures were extractable using different leaching methods and allowed paleoreconstructions for the past 3 - 5 Ma. The Nd and Pb isotope records of ferromanganese coatings of Site 911 on the Yermak Plateau showed only small variations prior to 2.7 Ma pointing to a continuous Atlantic inflow under generally warmer climatic conditions. In contrast, since the intensification of the Northern Hemisphere Glaciation the Nd isotope composition has shown a high variability as a consequence of the glacial/interglacial waxing and waning of ice sheets on Svalbard, the Barents Sea, and Eurasia. The Pb isotope record at the same time reveals a trend to more radiogenic values as a result of increasing glacial weathering inputs from old continental landmasses after 2 Ma. Comparison of the Nd isotope records of ODP Sites 986, 644 and 982 reveal that warmer periods and moderate glacial conditions were accompanied by enhanced Atlantic inflow into the Nordic Seas prior to the onset of the NHG at 2.7 Ma and between 2.2 Ma and 1.5 Ma. In contrast, at the beginning of the MPT between 1.5 and 1.2 Ma the Atlantic inflow was significantly reduced, expressed as marked by pronounced differences between the Nd isotope records in the Nordic Seas and North Atlantic Ocean. Sediment provenance obtained from Nd and Pb isotope compositions of the detrital material shows a variable influence of Svalbard, Barents Sea and Eurasian shelf at the sites on the Svalbard margin and on Yermak Plateau. The Vøring Plateau has been dominated by sediment input from Scandinavia to which material from the Barents Sea was added via icebergs and sea ice during glaciations. In contrast, the Rockall Plateau showed the lowest erosional influence and variability due to its location most distant from land.
Projektbezogene Publikationen (Auswahl)
- Plio-Pleistocene changes in water mass exchange and erosional input in the Fram Strait. In: 10th International Conference on Paleoceanography, 29.08.-03.09. 2010, La Jolla, California, USA
Teschner, C., Frank, M. und Haley, B. A.
- Plio-Pleistocene changes in water mass exchange and erosional inputs in the Fram Strait. In: EGU General Assembly, 03.04.-08.04.2011, Vienna, Austria
Teschner, C., Frank, M., Haley, B. A., Knies, J. and Christl, M.
- Plio-Pleistocene evolution of water mass exchange and erosional input in the Fram Strait. In: Goldschmidt conference 2011, 14.08.-19.08. 2011, Praque, Czech Republic
Teschner, C., Frank, M., Haley, B. A. and Knies, J.
- Plio-Pleistocene evolution of water mass exchange and erosional input in the Nordic Seas. In: Goldschmidt conference 2012, 23.07.-27.07.2012, Montreal, Canada
Teschner, C., Frank, M., Haley, B. A. and Knies, J.
- Plio-Pleistocene evolution of water mass exchange and erosional input in the Nordic Seas. In: International conference of the Geologische Vereinigung and Sediment, 23.09.-28.09.2012, Hamburg, Germany
Teschner, C., Frank, M., Haley, B. A. and Knies, J.
- 2013. Reconstructing the Plio – Pleistocene evolution of the water mass exchange and climate variability in the Nordic Seas and North Atlantic Ocean. PhD. thesis, University of Kiel, 189 pp.
Teschner, C.
- Plio-Pleistocene evolution of water mass exchange and erosional input at the Atlantic-Arctic gateway. Paleoceanography and Paleoclimatology, Vol 31 Iss 5, May 2016, Pages 582-599
Teschner, C., Frank, M., Haley, B.A. and Knies, J.
(Siehe online unter https://doi.org/10.1002/2015PA002843)
