Insights into the structural geology and sedimentary succession of the Baltic Basin, Western Lithuania

The geological structure of the sedimentary cover of the Baltic Basin has been investigated since the 1960's. In Western Lithuania, seismic data were acquired during 1995-2015; however, the interpretation results have remained largely unpublished. In this work, the relatively newly acquired 2D and 3D seismic data have been incorporated into a single seismic interpretation. Detailed depth maps for the key seismic reflection horizons, an updated presentation of fault traces, as well as a few representative seismic profiles are made to illustrate the geological structure of the study area, which is in Western Lithuania and spans nearly 360 km2. This area includes Late Caledonian structures, such as the Garg.zdai Elevation, which contains some of the Lithuanian hydrocarbon fields, and is limited by the Garg.zdai Fault. This study demonstrates that the Garg.zdai Fault is not a single continuous fault, but rather it comprises a system of faults. Moreover, the Garg.zdai Elevation itself contains small-scale structures that are either fault-related, cross-faults, drape structures or combined types. In addition to previously known large separated Precambrian palaeo-topographical features, additional features are mapped as a result of this study. They are interpreted as erosional remnants (inselbergs) on the sub-Cambrian peneplain surface, and form a large group of inselbergs, which is not typical of the Baltic Basin. Several structural features related to Zechstein Basin are mapped as well: the northern edge of Zechstein evaporites and, possibly, Permian reefs.

Automated summary

The geological structure of the sedimentary cover of the Baltic Basin in Western Lithuania has been investigated using newly acquired seismic data. The study reveals detailed depth maps and seismic profiles that illustrate the geological structure of the area, including new features such as erosional remnants and structural features related to the Zechstein Basin.