3.2.1. Rationale
Under the auspices of the World Stress Map project and the Origin of Sedimentary Basins Task Force, both sponsored by International Lithosphere Program (ILP), new databases were developed during the last decade for the stress field and recent crustal-scale vertical motions on the Phanerozoic European Platform. On the basis of these, close links could be established between the stress field, the Neogene to Quaternary intraplate deformation, and the distribution of seismic activity and topography. The present-day stress field of Western and Central Europe (Müller et al., 1997) could be successfully modelled by taking Alpine collisional coupling and Atlantic ridge-push forces into account (Gölke and Coblentz, 1996; Ziegler et al., 2002; Guimerà et al., 2004). Furthermore, acquisition of high-quality tomographic data (Goes et al., 2000a) permitted to image the thermal structure of the sub-lithospheric mantle beneath the West and Central European Platform, revealing that in the area of the European Cenozoic rift system (ECRIS) thermal anomalies occur immediately above the 410 km discontinuity. These can be interpreted as the heads of mantle plumes from which secondary plumes intermittently welled up (Dèzes et al., 2005), as currently evident beneath the Massif Central (Granet et al., 1995) and the Eifel region of the Rhenish Massif (Ritter et al., 2001).
There is increasing evidence that the West and Central European lithosphere responds to the build-up of intraplate compressional stresses by lithospheric folding (Cloetingh et al., 1999), as evidenced for instance by the Plio-Pleistocene subsidence acceleration of the North Sea Basin and contemporaneous uplift of the Fennoscandian Shield (Cloetingh and Burov, 1996; Van Wees and Cloetingh, 1996). In this context, it is noteworthy that studies on mechanical properties of Europe's lithosphere reveal a direct link between its thermo-tectonic age and bulk strength, whereas inferences from P- and S-wave tomography and thermo-mechanical modelling point to pronounced weakening of the lithosphere in the area of the Massif Central and Rhenish Massif owing to high upper mantle temperatures (Cloetingh et al., 2005b). Uplift of the Rhenish Massif by as much as 250 m during the last 0.8 My (Van Balen et al., 2000; Meyer and Stets, 2002) can be directly attributed to the load of an impinging mantle plume and related thermal thinning of the lithosphere (Garcia-Castellanos et al., 2000; Dèzes et al., 2004).
The evolution of ECRIS and the progressive uplift of the Massif Central, the Vosges Black Forest Arch and the Rhenish and Bohemian Massifs during the last 20 My had severe repercussions on the development of the drainage system on the West and Central European Platform (Sissingh, 2006; Ziegler and Dezes, 2007). As parts of this drainage system are prone to repeated catastrophic flooding, as seen for instance in Northern Germany and Poland, it is highly susceptible to neotectonic deformations.
Assessment of crustal and lithospheric controls on the neotectonic deformation of the North-European Alpine foreland was the focus of the European ENTEC program that integrated geological, geophysical, geodetic, geomorphologic, and geotechnological approaches (Cloetingh and Cornu, 2005a). Results of this pioneering program show that monitoring of the subsurface by 3-D seismic, combined with satellite-based geodetic monitoring of horizontal and vertical crustal motions, permits to extend the record of neotectonic activity and related topography development into the domain of 100,000 to a few million years, thus building up a large database for validation of process modelling. This approach will be further refined by TOPO-EUROPE. Within the West and Central European Platform natural laboratory, TOPO-EUROPE will addresses four specific areas and their inherent neotectonic phenomena. These are:
- Neotectonics of the Rhine Graben system
- Vulnerability of the Rhine-Meuse delta system
- Seismicity and neotectonic deformation of the Armorican Massif
- Neotectonic uplift of the Bohemian Massif