Lithosphere tectonics and thermo-mechanical properties: an integrated modeling approach for EGS exploration in Europe

For geothermal exploration and production of enhanced geothermal systems (EGS)<br>knowledge of the thermo-mechanical signature of the lithosphere and crust is important to<br>obtain critical constraints for the crustal stress field and basement temperatures. The stress<br>and temperature field in Europe is subject to strong spatial variations which can be linked to<br>Polyphase extensional and compressional reactivation of the lithosphere, in different modes<br>of deformation. The development of innovative combinations of numerical and analogue<br>modeling techniques is key to thoroughly understand the spatial and temporal variations in<br>crustal stress and temperature. In this paper we present an overview of our advancement<br>developing and applying analogue and numerical thermo-mechanical models to<br>quantitatively asses the interplay of lithosphere dynamics and basin (de)formation. Field<br>studies of kinematic indicators and numerical modeling of present-day and paleo-stress fields<br>in selected areas have yielded new constraints on the causes and the expression of<br>intraplate stress fields in the lithosphere, driving basin (de)formation. The actual basin<br>response to intraplate stress is strongly affected by the rheological structure of the underlying<br>lithosphere, the basin geometry, fault dynamics and interplay with surface processes.<br>Integrated basin studies show that rheological layering and strength of the lithosphere plays<br>an important role in the spatial and temporal distribution of stress-induced vertical motions,<br>varying from subtle faulting to basin reactivation and large wavelength patterns of<br>lithospheric folding, demonstrating that sedimentary basins are sensitive recorders to the<br>intraplate stress field. The long lasting memory of the lithosphere, in terms of lithospheric<br>scale weak zones, appears to play a far more important role in basin formation and<br>reactivation than hitherto assumed. A better understanding of the 3-D linkage between basin<br>formation and basin reactivation is, therefore, an essential step in research that aims at<br>linking lithospheric forcing and upper mantle dynamics to crustal vertical motions and stress,<br>and their effect on sedimentary systems and heat flow. Vertical motions in basins can<br>become strongly enhanced, through coupled processes of surface erosion/sedimentation<br>and lower crustal flow. Furthermore patterns of active thermal attenuation by mantle plumes<br>can cause a significant spatial and modal redistribution of intraplate deformation and stress,<br>as a result of changing patterns in lithospheric strength and rheological layering. Novel<br>insights from numerical and analogue modeling aid in quantitative assessment of basin and<br>basement histories and shed new light on tectonic interpretation, providing helpful<br>constraints for geothermal exploration and production, including understanding and<br>predicting crustal stress and basin and basement heat flow.