The Lower Palaeozoic sediments in the Upper Silesian Block

Abstract

The Lower Palaeozoic sediments in the Upper Silesian Block are represented by the Lower Cambrian Sub-Holmia Zone (the Borzęta Formation) and the Lower Cambrian Holmia Zone (the Goczałkowice Formation). Sediments of the Borzręta Formation occur only in the eastern and likely in the northern part of the Upper Silesian Block. They are covered in transgressively by sediments of the Goczałkowice Formation also of Lower Cambrian age. Thickness of the Lower Cambrian sediments increases from the south and south-west to the east and north. In the eastern part of the block, a total thickness of the Lower Cambrian reaches approx. 3000 m. The northern part of the Upper Silesian Block is the area where only partial profiles of the Middle Cambrian and Ordovician have been recognized. Sediments of both the Cambrian and Ordovician within the Upper Silesian Block differ with respect to their tectono-stratigraphic development from the Lower Palaeozoic and Vendian rocks occurring within the western part of the Małopolska Block. Close neighbourhood of both types of development suggests that tectonic contact of both blocks exists along a narrow (approx. 0.5 km) tectonic zone.