Characterizing and mapping the regional extent of the Lower Paleozoic shales in Poland has, in the past, been challenging. However, the integration of newly-acquired broadband seismic data, designed to image deeper within the basins and with greater resolution, and key well data has more clearly defined the tectonic structure and regional depositional architecture of the Upper Ordovician-Silurian succession.
The Lower Paleozoic basin in Poland is located above the southwest edge of the East European Craton, northwest from the Teisseyre - Tornquist Zone which is separating the cratonic plate from the West European Platform (Fig. 1; Ziegler, 1992; Doornenbal & Stevenson, 2010).
Later Late Paleozoic tectonic movements resulted in compartmentalization of the Lower Paleozoic basin into three sub-basins: Baltic Basin, Podlasie Basin and Lublin Basin (Fig. 2).
During the Precambrian/Cambrian, the cratonic edge underwent extension and rifting of the Rodinia supercontinent, while Cambrian - Middle Ordovician subsidence was driven by a post-rift lithospheric thermal cooling (Poprawa et al., 1999; Poprawa, 2006a). In the Late Ordovician - Silurian, the cratonic edge was under the strong influence of the Caledonide thrust belt, and was incorporated into its flexural foredeep basin (Poprawa et al., 1999; Nawrocki & Poprawa, 2006). Deposition was dominated by fine-grained organic rich shales, generally derived from the eroded orogenic wedge and deposited in the distal foredeep basin (Poprawa et al., 1999; Poprawa, 2006b). The Silurian Caledonian foredeep basin encompassed vast areas stretching from the present-day Sweden across Estonia, Latvian, Lithuania, Russia (i.e. Kaliningrad District), Poland, Belarus, Ukraine and farther to the southeast (Poprawa et al., 1999; Skompski et al., 2008; Zdanaviciute and Lazauskiene, 2007). Presently available information regarding the Caledonian orogenic wedge is very limited and mostly indirect, based on e.g. provenance studies of the foredeep infill, as it was destroyed and deeply buried during the later tectonic phases (Poprawa, 2006b).