Precambrian and Lower Paleozoic of the Brunovistulicum (eastern part of the Upper Silesian Block, southern Poland) : the state of the art

The Precambrian basement and Lower Paleozoic (Cambrian–Ordovician) sedimentary cover in the eastern part of the Upper Silesian Block (Brunovistulicum), known only in boreholes, is presented, and their palaeogeographic, facies and palaeotectonic development is discussed. The former is characterized by a heterogeneous structure that consists of Archean-Lower Proterozoic and Neoproterozoic rocks of different lithologies and origins, and the latter is almost exclusively represented by marine, transitional and terrestrial siliciclastic rocks. In contrast to the neighbouring region of the western part of the Małopolska Block, the siliciclastic sedimentation took place during the Early and Middle Cambrian in this area, however, the Ordovician deposits were encountered in several boreholes and no Silurian rocks have been reported in the northern part of this region. The authors present the most probable model of sedimentation, tectonics and origin of the geological structure of the Lower Paleozoic sedimentary cover in the Upper Silesian Block, define research problems, and justify the need for new drillings. Based on the geological and structural analysis of the depth to the top surface of the Lower Paleozoic, they define the optimal location for three 1500 m deep boreholes to solve the basic research problems.