Description:

The Fram Strait is the ocean region between Svalbard and Greenland. Because of tectonic movements the opening of the Fram Strait and the final separation of Greenland and Svalbard, on the Greenland Plate and the Eurasian Plate respectively, began at about 12 Ma. New oceanic crust was formed and a new mid – ocean - ridge between the Mohn's Ridge and the Gakkel Ridge began to evolve. The role of this Arctic gateway is debated. Does the Fram Strait offer a possibility to exchange dense oxygen-rich deep water between the Greenland Sea and the central Arctic Ocean? If and when it had a significant influence on global climate is not known in detail yet.

Besides existing seismic, magnetic and satellite based gravimetric data and data from ODP boreholes, new seismic and aeromagnetic data were collected by “RV Polarstern” and AWI aircraft to provide detailed information about past and present tectonic activity in the Fram Strait region. For this Ph.D. thesis it is planned to compile an animated reconstruction of the opening of the area from the Fram Strait in the north to the Iceland – Faroes – Ridge in the south.

For this animation, the following items will be investigated:

• Magnetic isochrons will be reidentified. With the help of new magnetic data, it is possible to make a more detailed definition of the age of the oceanic crust. On the basis of magnetic anomalies, different isochrons can be identified in the Fram Strait and adjacent regions.
• The basement roughness will be analysed to estimate the spreading velocity in areas where no clear magnetic isochrons can be identified (e.g. in the Boreas Basin).
• The seismic and gravimetric data are used to make an estimation of the location of the continent – ocean transition. In addition, it is hoped that the position of the present mid - ocean - ridge in the Lena Trough can be verified.
• To reconstruct blocks of oceanic crust of the same age, existing poles of rotation will be used. Current grids of magnetic, gravimetric and bathymetric data can be rotated to illustrate the former positions of the basins. The new reconstructions for different ages will provide a basis for detailed paleobathymetric maps.
• Maps of previous opening scenarios will be produced.
• To get more information about the region, seismic reflection data has to be fully processed and seismic refraction data from sonobuoys has to be analyzed.
• The reconstruction and modelling of the opening of the Boreas Basin, Lena Trough and Molloy Ridge will be done. This might allow a better insight into how, when and why the basins developed.
• Interpretations of the accumulation of sediments and sediment thickness will help to estimate the sediment load.
• The glacial sediments will be identified in order to estimate the amount of erosion of the shelf areas.
• Knowing the age of the crust from the magnetic anomalies and the sediment load from the seismic data, subsidence will be calculated to get an idea of water depth at different geological times.
• Estimates of the volume of water masses that might have circulated through this region will be provided for different time periods.

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