The Polish Sudetes: Caledonian or Variscan?

The Polish Sudetes on the NE margin of the Bohemian Massif comprise a compl ex mosaic of pre-Permian basement units, traditionally included in the Vari scides. A hypothesis of significant Caledonian orogenesis in this area orig inated in the 1920s, was subsequently rejected, and then was recently reviv ed in models which invoked Early Palaeozoic to Early-Mid Devonian subductio n and continental collision along a proposed extension of the Tornquist sut ure zone. We reassess the evidence invoked in support of the Caledonian oro geny, such as supposed regional pre Upper Devonian unconformity, Ordovician bimodal magmatism and radiometric, palaeontological, palaeomagnetic and st ructural data, and suggest these are either inconclusive or misinterpreted. On the other hand, the Sudetes record Mid?-Late Devonian blueschist metamo rphism followed by an Early Carboniferous regional high temperature event, widespread Late Devonian/Early Carboniferous flysch/molasse sedimentation a nd abundant granite intrusion in the Carboniferous to Early Permian. We dis cuss the usage of the term 'Caledonian' in a plate tectonic context and sug gest it should not be used simply to denote Early to Mid-Palaeozoic tectoni c activity. The tectonic evolution of the Sudetes was temporally different from, and resulted from convergence of different crustal domains than that of the British-Scandinavian-Pomeranian Caledonides. The Sudetic Palaeozoic sequences most probably developed on Armorican Neoproterozoic crust and in adjacent oceanic(?) domains and, therefore, the Sudetes form part of the Va riscan orogenic belt.