Improved geophysical image of the Carpathian-Pannonian Basin region

Abstract

Our paper presents the general overview of the current geophysical results, which helps to improve the geophysical image and the lithospheric structure of the Carpathian-Pannonian Basin region. Two different geophysical methods have been applied for the study of the structure and composition of the lithosphere as well as for determination of the lithospheric thermal structure. Firstly, integrated 2D modeling of gravity, geoid, topography and surface heat flow data was performed. Secondly, based on the results of the CELEBRATION 2000 seismic experiment, a large-scale 3D lithospheric gravity model was developed. The resulting map of the lithospheric thickness shows important variations in lithospheric thickness across the chain as well as along strike of the Carpathian arc. The sediment stripped gravity map is characterized by minima in the Eastern Alps and Western Carpathians. The maxima are observed in the Pannonian Back-arc Basin system, Bohemian Massif, Fore-Sudetic Monocline, Bruno-Silesian unit (BSU), Lublin Trough and partly in the Holy Cross Mts. and Malopolska unit. The Western Carpathian gravity minimum is a result of the interference of two main gravity effects. The first one comes from the low-density sediments of the Outer Western Carpathians and Carpathian Foredeep. The second one is due to the thick low-density upper and middle crust, reaching up to 25 km. The sediment stripped anomaly in the Pannonian Back-arc Basin system is characterized by gravity high that is a result of the gravity effect of the anomalously shallow Moho. The most dominant feature of the complete stripped gravity map is the abrupt change of the positive anomalies along the Pieniny Klippen Belt zone. The complete residual anomaly of the Pannonian Back-arc Basin system and the Western Carpathian orogen is characterized by a long-wavelength gravity low. The lowest values are associated with the thick low-density upper and middle crust of the Inner Western Carpathians. The European Platform is characterized by significantly denser crust with respect to the less dense crust of the microplates ALCAPA and Tisza-Dacia. That is why we suggest that the European platform represents consolidated, while the Carpathian-Pannonian Basin region un-consolidated crust.