Principal characteristics of the Upper Silesian Block and Małopolska Block border zone (southern Poland)

The Upper Silesian and Małopolska blocks are situated near the southwestern boundary of the East European Platform within the Trans-European Suture Zone. The Lower Palaeozoic lithologies of the blocks reveal different stratigraphic and diastrophic development. In the Upper Silesian Block, unmetamorphosed and gently folded Lower Cambrian to Ordovician sedimentary rocks rest on a Cadomian basement. The Lower Cambrian is represented by an older (sub-Holmia) Borzęta Formation and a younger (Holmia) Goczałkowice Formation. The thickness of the Cambrian lithologies increases from the southwest towards the lateral part of the block. In the Małopolska Block Palaeozoic and Precambrian lithologies are represented by regionally metamorphosed and intensely folded Lower Cambrian–Vendian clastic rocks which are unconformably overlain by Ordovician–Lower Silurian carbonates and Upper Silurian clastic rocks. The crystalline basement of the Małopolska Block has yet to be recognized. The Lower Palaeozoic sediments of both blocks are overlain by Devonian and Carboniferous rocks. The blocks are in direct contact along a narrow tectonic zone, a part of the largely concealed Hamburg–Kraków fault zone, in which tectonic evolution has taken place spasmodically with strike-slip movements predominating.