Jurassic tectonic events in south-eastern cratonic Poland

Abstract

The Meta-Carpathian Arch, that comprised cratonic areas of SE Poland, usually experienced in the Mesozoic much less subsidence, or showed uplift, with regard to the Polish part of the Central European Basin situated farther north. In marked contrast, the areas of the Meta-Carpathian Arch were affected by strong subsidence in Middle and Late Jurassic time, and the peri-Carpathian segment of the Polish Rift began to develop in the Middle Jurassic as a southern extention of that rift, the existence of which north of the Holy Cross Lineament dates back to the Triassic or Permian. A stronger attenuation of continental crust can be recognized south of the Holy Cross Transfer Fault, which bounded the peri-Carpathian segment to the north; this is a feature consistent with the extention of the Polish Rift into the domain of the Carpathian Tethys. The Jurassic tectonic events controlled in the studied areas the formation of the three transgressive-regressive tectono-stratigraphic units: the COK Sequence (CaIlovian, Oxfordian and Lower Kimmeridgian, upper boundary near the top of the Hypselocyclum Zone); the LUK Sequence (Lower and Upper Kimmeridgian, upper boundary within the Eudoxus Zone); and the KVB Sequence (topmost Kimmeridgian, Volgian and Lower Berriasian). Coeval tectonic events, corresponding to those recorded in cratonic Poland, can be recognized in different parts of Europe, particularly in the Carpathians. The alternating phases of relative uplift and subsidence, experienced by the areas of the Meta-Carpathian Arch that flanked the Central European Basin on the south, can be attributed to fluctuations of intraplate stresses. The peculiar behavior of the Cracow region in Mesozoic and Miocene time, as an area never affected by strong subsidence, is thought to have resulted from the presence of Variscan granitoids at its depths. A development of the Polish Rift Basin in agreement with models assuming simple shear on Iithospheric scale is suggested.