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The investigated area comprises two Neogene molasse basins, namely the Transylvanian basin and the eastern part of the Pannonian basin, with a different tectonic origin, in spite of coincidence in time and place of their evolution, and Apuseni Mountains, an isolated massive inside the Carpathian arc. The structure peculiarities of the lithosphere in the study area are consequences of the eastward movement of the Intra-Carpathian units and of their continental collision with the European Plate during formation of the Carpathian arc in Tertiary times. In this study a special regard is focused on the Transylvanian basin, viewed as a transition zone between the extending and shortening parts of the upper plate involved in a final stage of a soft collision process. The evaluation of the thermal structure beneath continental zones requires realistic estimates on crustal structure and distribution of the thermal parameters within the lithosphere. For the stable parts of the lithospheric compartments, where the temperature of the upper mantle could be approximated by a steady-state solution of the 1-D and 2-D thermal conductive equation with boundary conditions, the average value of the surface heat flux is used in obtaining the characteristic geotherm (heat flow derived geotherm). For the tectonically regenerated Intra-Carpathian zones, acceptable temperature models are obtained by thermal simulation of the main tectonic processes affecting the lithospheric structure, namely sedimentation and erosion in Transylvanian and Pannonian Depressions and generation of magmas in the Neogene volcanic area of the Eastern Carpathians) using finite-elements and finite-differences computer codes. Applying a conversion procedure of seismic wave velocity to temperature, the study proposes a re-evaluation of temperature models for the lithosphere in the Intra-Carpathian area, by assimilation of the information supplied by tomographic seismic data. The result of this study consists of profiles of the temperature distribution with depth, in the crust and mantle, which are then valued in producing rheological profiles using the concept of strength envelopes. The obtained rheological structures for the study area are interpreted in correlation with the characteristics of the seismic wave propagation process (quality factor of the medium Q).
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