Late Carboniferous–early Permian events in the Trans-European Suture Zone: Tectonic and acid magmatic evidence from Poland

Abstract

The Trans-European Suture Zone (TESZ) links the East and West European Platforms. It is concealed under Meso-Cenozoic cover. Available seismic data show that the lower crustal layer in the TESZ is an attenuated, ~200km wide, SW margin of Baltica. The attenuation occurred when Rodinia broke-up, which gave rise to evolution of the thinned, thus relatively unstable margin of Baltica. It accommodated accretions during Phanerozoic events. We focus on acid magmatism, specifically granitoid, observed close to the SW border of the TESZ in Poland. This border is defined by the Dolsk Fault Zone (DFZ) and the Kraków-Lubliniec Fault Zone (KLFZ) on which dextral wrenching developed as a result of the Variscan collision between Laurussia and Gondwana. The granitoids at the DFZ and KLFZ were dated at ~300Ma. In the Variscan foreland that overlaps the TESZ, orogenic thickening continued to ~307–306Ma, possibly contributed to melting of the thickened upper continental crust (εNd300=−6.0 to −4.5) and triggered the tectonically controlled magmatism. The wrenching on the TESZ border faults caused tensional openings in the basement, which promoted magmatic centers with extrusions of rhyolites and extensive ignimbrites. The Chrzypsko–Paproć and Małopolska magmatic centers were developed at the DFZ and KLFZ, respectively. The magmatic edifices commenced at ~302Ma with relatively poorly evolved granites, which carried both suprasubduction and anorogenic signatures, then followed by more evolved volcanic rocks (up to 293Ma). Their geochemistry and inherited zircons suggest that the felsic magmas were mainly derived from upper crustal rocks, with some mantle additions, which included Sveconorwegian and older Baltican components. The complex TESZ, with Baltica basement in the lower crust, was susceptible to transient effects of mantle upwelling that occurred by the end of the Variscan orogeny and resulted in an episode of the “flare-up” magmatism in the North German–Polish Basin.