The study of crustal structures in the southwestern part of the Baltic Sea by modeling of gravity data

The southwestern part of the Baltic Sea, including parts of the central European system, the Torne European Suture Zone, and the Ringkobing-Fyn High, is one of the most attractive areas for geoscientists due to its complicated geological structure caused by different tectonic events. In this paper, a local three-dimensional model of the crustal structures was developed based on interactive forward modeling of gravity data in the southwestern part of the Baltic Sea. The model considers sedimentary layers, upper crust, lower crust, and part of the upper mantle and applies the information of the area, including crustal thickness and Moho topography. Seismic sections and existing models in the area were used as the primary information to generate an appropriate initial model to reduce the problem of non-uniqueness, which is recognized as an inherent problem in potential fields modeling. The results indicated that the crustal thickness in the study area varies from 20 to 35 km. The thickest part is located in the Precambrian Baltic crust in the northeastern part of the region, and the thinnest part is in the margin of the Northern German Basin. The depth of Moho discontinuity in this area also varies from 26 to 42 km and shows significant changes on the sides of the Tornquist Zone.