The Upper Silesian and Maĺopolska 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) Goczaĺkowice Formation. The thickness of the Cambrian lithologies increases from the southwest towards the lateral part of the block. In the Maĺopolska 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 Maĺopolska 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.

The Brunovistulian was one of the first tectonic units of Central Europe to be defined as a ‘terrane’. In spite of extensive studies, the Early Palaeozoic palaeogeographical position and provenance of this unit remains unclear. A palaeomagnetic study of the Lower Cambrian red beds and a study of the trilobite fauna were performed to provide constraints on the palaeogeographical position of the terrane in Early Cambrian time. Good quality palaeomagnetic data obtained from the Lower Cambrian red beds suggest the mixed nature of the Early Cambrian geomagnetic field and a nearly equatorial position (a palaeolatitude of c . 7°) of the Brunovistulian terrane in the Early Cambrian. Comparison of this palaeolatitude with existing palaeogeographical models leads to the conclusion that at this time the Brunovistulian terrane was separated by a great distance from the Avalonian margin of Gondwana. The terrane was located within the Cadomian belt, occupying a position north of the present-day northern margin of Africa. It was coupled to the present-day southern margin of Baltica during the Cambrian, when Baltica moved along the Cadomian margin of Gondwana. Another possibility is that the Brunovistulian terrane could have remained near this margin of Baltica since Grenvillian time and was incorporated into the Cadomian orogen.

The Pre cam brian base ment and Lower Pa leo zoic (Cam brian-Or do vi cian) sed i men tary cover in the east ern part of the Up per Silesian Block (Brunovistulicum), known only in bore holes, is pre sented, and their palaeogeographic, fa cies and palaeotectonic de vel op ment is dis cussed. The for mer is char ac ter ized by a het er o ge neous struc ture that con sists of Archean-Lower Pro tero zoic and Neoproterozoic rocks of dif fer ent lithologies and or i gins, and the lat ter is al most ex clu sively rep re sented by ma rine, tran si tional and ter res trial siliciclastic rocks. In con trast to the neigh bour ing re gion of the west ern part of the Ma³opolska Block, the siliciclastic sed i men ta tion took place dur ing the Early and Mid dle Cam brian in this area, however, the Or do vi cian de pos its were en coun tered in sev eral bore holes and no Si lu rian rocks have been re ported in the northern part of this re gion. The au thors pres ent the most prob a ble model of sed i men ta tion, tec ton ics and or i gin of the geo log i cal struc ture of the Lower Pa leo zoic sed i men tary cover in the Up per Silesian Block, de fine re search prob lems, and jus tify the need for new drillings. Based on the geo log i cal and struc tural anal y sis of the depth to the top sur face of the Lower Pa leo zoic, they de fine the op ti mal lo ca tion for three 1500 m deep bore holes to solve the ba sic re search prob lems.Key words: Pre cam brian base ment, Lower Pa leo zoic sed i men tary cover, Up per Silesian Block, Brunovistulicum, south ern Po land.

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