Determination of the continental lithospheric thermal structure in the Western Carpathians: integrated modelling of surface heat flow, gravity anomalies and topography

Abstract

Abstract Various interpretations of seismic, magnetotelluric and geothermal data have resulted in distinctly different models of the structure and thickness of the lithosphere in the Western Carpathian–Pannonian Basin region. The model inconsistencies, which are at least partly due to the use of non-unique single-method data inversion, led us to the application of integrated lithospheric multi-method modelling. Our approach combines the interpretation of surface heat flow, gravity and topography (local isostasy) data in order to constrain the continental lithospheric thermal structure along five transects crossing the Western Carpathians from the Polish platform and the Bohemian Massif to the Pannonian Basin. The results indicate clear variations of the lithosphere thickness along the Western Carpathian orogen not only in NS direction but also in WE direction. The lithospheric thickness is found to be 90–120 km underneath the Bohemian Massif, 115–140 km beneath the Polish platform and 75–100 km beneath the Pannonian Basin. A thick lithosphere (up to 130–150 km) is indicated underneath the central and eastern segments of the Western Carpathians with a tendency of thickening eastwards. This structure is interpreted as a remnant of a subducted slab of the European plate. In contrast, no lithospheric root shows up in our models of the westernmost segment of the Western Carpathians. We suggest that this difference indicates that in the transition zone from the Eastern Alps to the Carpathians, strike-slip movements predominated during the entire convergence period and no clear slab was produced in this area.