The Scandinavian mountain chain: deep processes (TopoScandiaDeep)
Final Report Abstract
TopoScandiaDeep was a research project to study the deep structure of the Scandinavian Mountains. These mountains form the second largest mountain belt in Europe and their present high topography cannot be explained with standard plate tectonic models. Within the international ESF programme TOPO-EUROPE, TopoScandiaDeep was conducted with partners from Denmark, Netherlands, Norway, Sweden and the United Kingdom. The main research was the analysis of earthquake and explosion recordings which were measured during seismological experiments. At the Karlsruhe Institute of Technology, we analysed the shear waves of far-distant earthquakes which carry information on the deep structure. With 3-D tomography imaging we recovered a low seismic velocity anomaly in the upper mantle down to 400 km depth. This anomaly may be caused by increased temperature which can also reduce density. Thus hot buoyant mantle material may support at least partly the high topography of the Scandes. Measurements of seismic anisotropy, that is a direction dependency of the propagation speed of earthquake waves, found a high spatial variability. This may reflect complicated deformation processes at depth. The analysis of mode-converted earthquake waves (from an elastic shear wave to a compressional wave) revealed discontinuities or layer boundaries at depth. One is the boundary between the Earth’s crust and mantle (Moho) and the topography of the Moho could be mapped. An increase in crustal thickness from the coast of Norway towards east is found. Deeper boundaries were also imaged which may include the boundary between the rigid lithospheric plate and the more ductile asthenosphere in the upper mantle (LAB). The LAB also dips from the Norwegian coast towards east. These new, data-based structural results will be used as boundary conditions for geodynamic modelling of the Scandinavian region.
Publications
- 2013. The deep structure of the Scandes and its relation to tectonic history and present topography, Tectonophysics, 602, 15- 37
Maupin, V., Agostini, A., Artemieva, I., Balling, N., Beekman, F., Ebbing, J., England, R.W., Frassetto, A., Gradmann, S., Jacobsen, B.H., Köhler, A., Kvarven, T., Medhus, A.B., Mjelde, R., Ritter, J., Sokoutis, D., Stratford, W., Thybo, H., Wawerzinek, B. & Weidle, C.
(See online at https://doi.org/10.1016/j.tecto.2013.03.010) - 2010. MAGNUS – a seismological broadband experiment to resolve crustal and upper mantle structure beneath the southern Scandes mountains in Norway. Seis. Res. Lett., 81, 76-84
Weidle, C., Maupin, Ritter, J., Kværna, T., Schweitzer, J., Balling, N., Thybo, H., Faleide, J.I. & F. Wenzel
- 2012. Untersuchung der elastischen Scherwellenstruktur unter dem Südskandinavischen Gebirge. Dissertation, Karlsruhe Institute of Technology
Wawerzinek, B.
- 2013. Complex deep seismic anisotropy below the Scandinavian Mountains, Journal of Seismology, 17, 361-384
Roy, C. & Ritter, J.R.R.
(See online at https://doi.org/10.1007/s10950-012-9325-4) - 2013. New constraints on the 3-D shear wave velocity structure of the upper mantle underneath Southern Scandinavia revealed from non-linear tomography. Tectonophysics, 602, 38-54
Wawerzinek, B., Ritter, J.R.R. & Roy, C.
(See online at https://doi.org/10.1016/j.tecto.2012.12.033)
