کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4688274 | 1635788 | 2012 | 15 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: What compensates the topography of southern Norway? Insights from thermo-isostatic modeling What compensates the topography of southern Norway? Insights from thermo-isostatic modeling](/preview/png/4688274.png)
The origin of the high topography of the Norwegian Mountains is currently much debated. Several geophysical studies show that the uppermost mantle below southern Norway has anomalously low velocities as compared to other parts of the Baltic Shield. This study aims to shed lights on the structure of the lithospheric mantle below southern Norway by adapting and further refining a method based on isostatic and thermal equilibrium to compute temperature, temperature-related density and synthetic S-wave velocity in stable continental domains. The one-dimensional steady-state heat equation is used with topographic, Moho depth, crustal density and surface heat flow data. A condition of local isostasy is assumed and geoid undulations are used to constrain the range of possible lithosphere models.Results derived from this method suggest a thickening of the thermal lithosphere below southern Norway from west to east. The western part is found to have higher temperatures, lower densities and lower synthetic S-wave velocities than the eastern part, compatible with results from a recent P-wave travel time residual study. Comparison of the synthetic shear-velocity profiles beneath southwestern Norway with velocity profiles inverted from Rayleigh wave dispersion data suggests that the higher temperatures associated with a thinner lithosphere can explain parts of the seismic low-velocity anomaly.The inferred lithospheric structure is sensitive to uncertainties in the crustal input model, but the main features remain undisturbed by changes in the input data. The results show that the lithosphere of southwestern Norway can be in local isostatic equilibrium, if it is thinner and warmer than the lithosphere of eastern Norway. The present-day high topography may therefore be partially sustained by lower densities in the mantle lithosphere.
► We adapt a thermo-isostatic method and apply it to southern Norway.
► We model temperature and density in the mantle lithosphere.
► Prediction of S-wave velocities and comparison with seismic results.
► Average velocity of southern Norway typical of a tectonically younger platform.
► Low densities in the mantle contribute to the isostatic balance of western Norway.
Journal: Journal of Geodynamics - Volume 61, October 2012, Pages 105–119