Mesozoic and Cenozoic evolution of salt structures within the Polish basin: An overview

Abstract

Abstract The Permian–Cretaceous Polish Basin belonged to the system of epicontinental depositional basins of Western and central Europe and was filled with several kilometres of siliciclastics, carbonates, and also thick Zechstein (approximately Upper Permian) evaporites. Its axial part (the so-called Mid-Polish Trough) characterized by the thickest Permo-Mesozoic sedimentary cover, developed above the Teisseyre–Tornquist Zone, lithospheric-scale boundary separating the East European Craton and the Palaeozoic Platform. The Polish Basin was inverted in Late Cretaceous–Paleocene times. A synthesis of studies based on seismic reflection data allowed some general rules regarding salt tectonics of the Polish Basin to be formulated. Two general classes of structures genetically related to the presence of the Zechstein evaporites have been described: peripheral structures located within NE and SW flanks of the Polish Basin, outside its axial part and structures located within its axial part. The first class of structures includes grabens bounded by listric faults detached above salt or salt pillows that developed where Zechstein evaporites were of relatively smaller thickness and where sub-Zechstein fault tectonics played a relatively smaller role. The second class of structures includes more mature salt structures such as salt pillows and salt diapirs and is related to the more axial part of the basin, characterized by relatively thicker Zechstein evaporites and by more intense basement tectonics. First salt movements (salt pillowing) took place in the Early Triassic that in certain cases was followed by the Late Triassic salt diapirism and extrusion. In Jurassic–Early Cretaceous times, no significant growth of salt structures took place. Most of the salt diapirs have been finally shaped by the Late Cretaceous inversion tectonics. Some salt diapirs also underwent Cenozoic reactivation, associated with localized Oligocene or Miocene subsidence that in some cases was followed by younger (Pliocene–Quaternary) inversion and uplift.