Geotectonic setting of Permian polymetallic deposits in the Polish Basin

Abstract

The Polish Basin is located between the Precambrian East-European Platform and the Cadomian Bohemian and Małopolska massifs. The basement of this Permian-Mesozoic basin comprises mainly Variscides and epi-Caledonian Paleozoic rocks. In the proximal (NE) part of the basin, the Mid-Polish Trough is distinguished. In the distal (SW) part, the thickness of the Permian-Mesozoic succession is much smaller than in the Polish Trough. Palaeorift zones were active from the Permian to the end of the Jurassic in the distal part of this basin. The Kupferschiefer mineral system indicates a palaeorift zone and smaller hot spots as sources of supply of metalliferous brines. The relatively small thickness of the Rotliegend sandstones and their good permeability and porosity properties created very favourable routes for the migration of metal-bearing brines. The entire Kupferschiefer polymetallic reservoir is regionally sealed by anhydrites and salts of the Werra cyclothem. This was inclined constantly from Permian times onwards to the north, favouring the migration of polymetallic brines from rift zones to geochemical reservoir traps. Mineral system analysis of the polymetallic Kupferschiefer deposits shows that the geotectonic setting of this zone relates only to the distal part of the Polish asymmetric rift basin.