Application of two-dimensional gravity models as input parameters to balanced cross-sections across the margin of the East European Craton in SE Poland

Abstract

Our paper demonstrates how two-dimensional density models can deliver critical constraints that permit construction and validation of geological models in an underconstrained subcropped fold-and-thrust belt. As a case study, we use a newly discovered thrust-and-fold belt developed above the margin of the East European Craton (EEC) in SE Poland. A geological model constructed using gravity data resolved the basement-cover interface and a top-Cambrian horizon. This model was used as a framework for cross-section construction employing at this step also borehole and seismic evidence. Two cross-sections were created to address a source of uncertainty related to non-uniqueness of gravity modelling with different emphasis on gravimetric vs geological evidence. Model 1 strictly obeys the top-Cambrian derived from gravity modelling that was treated as an envelope of deeper structures. Model 2 allowed for local departures from the gravity model, especially in the case of conflicts with formation thicknesses. The comparison between the present structure and restorations allowed for separating effects of Caledonian and Variscan shortening. Although the fit of both models to the gravity data is satisfactory, model 2 better complies to geological constraints, resolving the long-discussed problem concerning the distribution and intensity of Caledonian tectonics across the SW periphery of the EEC.