Lower Paleozoic shales of the SW edge of the East European Craton in SE Poland and W Ukraine, their structure and tectonic evolution – regional comparison

Abstract

The Lower Paleozoic basin of Poland has recently been the focus of intensive exploration for shale gas; its continuation in W Ukraine also attracted several companies that applied for exploration concessions. This sedimentary basin developed above the SW edge of the East European Craton (EEC) and could be regarded, at least in general regional framework, as a distal part of the Caledonian foredeep basin. EEC edge in Poland and Ukraine is limited by the Teisseyre – Tornquist Zone (TTZ), crustal-scale fault zone characterized by a very complex tectonic structure formed during the entire Phanerozoic. In order to better understand Polish and Ukrainian counterparts of this sedimentary basin an attempt towards comparative analysis of selected geological and geophysical data has been made. In Poland, analysis of relatively rich database of archive and recently acquired seismic data calibrated by numerous deep research and exploration wells and supported by analysis of gravity and magnetic data provided new information on regional structure of the cratonic edge including: Neoproterozoic extensional structures and associated volcano-sedimentary cover possibly related to the Orsha-Volhyn Aulacogen, deeply rooted strike-slip fault zones located at boundaries of the Malopolska gravity high, SW-NE - trending system of mostly reverse faults related to the Bretonian (Early Carboniferous) reactivation of the Precambrian structures, thin-skinned Variscan (Late Carboniferous) compressional structures detached above top of the Precambrian basement or at the base of the Silurian shales, and regional reverse faulting related to the Late Cretaceous – Paleogene inversion of the MPT. In Ukraine, published material together with archive seismic data calibrated by several deep wells was used to determine main structural elements of the cratonic edge. Identified Paleozoic structural elements conform very well to their counterparts known from Poland, main difference being Neogene structural overprint related to the emplacement of the Outer Carpathian thrust belt and formation of the Carpathian foredeep basin.

AAPG Datapages/Search and Discovery Article #90226 © 2015 European Regional Conference and Exhibition, Lisbon, Portugal, May 18-19, 2015