Variscan to Alpine heterogeneous palaeo-stress field above a major Palaeozoic suture in the Carpathian foreland (southeastern Poland)

Abstract

The tectonic evolution of the region adjacent to the SW border of the East European craton is crucial for understanding the Palaeozoic amalgamation of Europe and its later evolution. We present a structural analysis of the brittle deformation (fault-slip data inversion) and folding carried out in the Cambrian to Cenozoic rocks of the European platform in SE Poland to characterize the Late Palaeozoic, Maastrichtian–Palaeocene and Miocene tectonics of this region. The Variscan (Late Carboniferous) palaeo-stress pattern was characterized by N–S to NNE–SSW-oriented compression, as inferred from the folding of the Palaeozoic (mainly Devonian) rocks. The compression was associated with the northwesterly (present-day coordinates) motion of Gondwana towards the northerly situated Laurussia. Subsequently, the Mid-Polish Trough (MPT) developed in an extensional regime. The stress regime changed to compressional at the Maastrichtian–Palaeocene transition in response to the Africa–Europe plate kinematics. The compressional regime induced the tectonic inversion of the Mid-Polish Trough. The stress pattern was characterized by NE–SW-oriented compression in the Holy Cross Mts. (HCM) area and in the Radomsko High. Folds and faults in the Mesozoic cover revealed a sinistral reactivation of the Holy Cross Fault (HCF) and of NW–SE-trending faults. The Alpine stress patterns were related to the subduction of the European platform beneath the Carpathian orogen. The flexural bending of the subducted lithosphere induced a homogeneous Middle Miocene N–S extension in the Carpathian foreland. Subsequently, the northward propagation of the Carpathian front resulted in late Middle Miocene N–S compression, restricted to the proximal area of the frontal thrusts, implied by a strain partitioning at a low friction contact between the Carpathian nappes and the European platform. Since the Palaeozoic, the Teisseyre–Tornquist Zone (TTZ) behaved as lithospheric weak zone, which has been reactivated during the Maastrichtian–Palaeocene change in stress regime. It resulted in the tectonic inversion of the Polish Trough. Inherited faults conditioned superficial stress perturbations and focused the deformation.