3D strength and gravity anomalies of the European lithosphere

Tectonic studies show that intraplate Europe is more active than might be expected from its tectonic setting. We employ integrative analysis of various datasets, which provides new understanding of deformation processes in response to different types of loading. A 3D strength model of the lithosphere, which is based on existing structural, compositional and thermal models of the lithosphere, forms the basis for this study. Boundaries of the crustal layers are determined from existing seismic data. Constraints on the thermal structure of the lithosphere are obtained from heat flow studies and upper mantle seismic tomography. The calculated strength distribution is used to quantify spatial variations in effective elastic plate thickness (EET) of the European lithosphere. A comparison with seismic and geodetic strain rates provides new insights into the localization of intraplate deformation. Another important indication of lithospheric strength is provided by the residual mantle gravity anomalies obtained after removing the crustal contribution from the observed gravity field. We have found significant spatial variations in rigidity within the Central and Western European lithosphere, in contrast with a more uniform strong lithosphere of the East European Platform. These variations are consistent with differences in the density structure of the mantle lithosphere reflected in mantle gravity anomalies. Western Europe is mostly characterized by negative mantle gravity anomalies and low EET values (generally ≤ 20 km), whereas the opposite is true for Eastern Europe. Large differences exist also for specific tectonic units: e.g. a pronounced contrast in lithosphere properties is found between the strong Adriatic plate and the weak Pannonian Basin area, as well as between the Baltic Shield and the North Sea rift system. We demonstrate that the European Cenozoic Rift System (ECRIS), which is characterized by low EET values and negative mantle gravity anomalies, localizes neotectonic deformation manifested by relatively high geodetic and seismic strain rates. © 2007 Elsevier B.V. All rights reserved.