Tektoniczne struktury deformacyjne w iłach krakowieckich sarmatu w Wylewie k. Sieniawy (zapadlisko przedkarpackie): świadectwo młodej przesuwczej aktywności podłoża miocenu

Tectonic deformation structures (folds, strike-slip, reverse and normal faults as well as joints) are reported here from the topmost part of the youngest, clayey sediments of the Carpathian foreland basin (Krakowiec clays, Sarmatian, Miocene), in a clay pit located at a village ofWylewa near Sieniawa. Our structural study has revealed several joint sets, accompanying products of intense folding and faulting, and defining a structural pattern that can be easily interpreted in terms of structures formed in a transpressive regime above strike-slip faults in the basement. The origin of these structures is ascribed to tectonic activity of the NW-SE-trending Ryszkowa Wola horst known to occur directly beneath the Wylewa clay pit, at a depth of c. 500 to 1300 m and to involve the basement and the lower part of theMiocene succession. The structural pattern in question most likely reflects a sinistral strike-slip displacement on sub-vertical boundary faults of the lowermost part of the horst. Undisputable effects of this strike-slip motion have been recently documented by other authors using 3D seismic data. The deformation structures at Wylewa must have resulted from a young, late to post-Sarmatian tectonic activity in the basement of the Carpathian foreland basin, probably reflecting an E-W to ENE-WSW directed regional shortening episode.