Abstract
In the present study we analyzed the influence of density heterogeneity in the sedimentary cover on estimates of the effective elastic thickness (EET) of the lithosphere based on a cross-spectral analysis of gravity and topography data. The fan wavelet coherence technique was employed to calculate EET for most of Europe and adjoining southern mountain belts. We employed Bouguer gravity anomalies and topography corrected for the effect of density variations within sediments. Correcting for sediments considerably suppresses the effect of unexpressed subsurface loads and substantially reduces EET estimates in areas with negligible topography variations as it was demonstrated for North Europe and East European Platform. The results show a good correspondence between the EET patterns and tectonic fragmentation of Europe and better agree with independent estimates based on the strength model of the lithosphere. Therefore, considering of the effect of sediments is essential for correct determinations of EET in flat areas.
Plain Language Summary The lithosphere is the outer rigid shell of the Earth, which overlies a viscous layer, called the asthenosphere. Knowledge of the lithosphere strength is important, for example, for understanding earthquake activity. Effective elastic thickness is a proxy for lithospheric strength and corresponds to the thickness of a homogeneous elastic plate, which deforms under loading in the same way as the real lithosphere. Thus, far, different methods used to determine this parameter have given controversial results. We demonstrate that considering the effect of sediments, which represent the soft uppermost crustal layer, provides a possibility for obtaining more consistent results. New effective elastic thickness estimates show that the European lithosphere is divided into two parts along the Trans European Suture Zone. Western Europe is characterized by predominantly low values of the effective elastic thickness and consequently weak lithosphere. In contrast, the lithosphere in Eastern Europe is much stronger. Regional variations of the effective elastic thickness obtained in this study are consistent with the tectonic partitioning of Europe with the surrounding mountain belts and help to understand ongoing tectonic processes.