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Which structural style to choose for constructing 3D geological model of the Lublin basin? Constraints from 2D seismic

13th Meeting of the Central European Tectonic Groups, At Kadaň, Czech Republic. 2015

Preliminary results of 2D seismic interpretation, constituting the basis for setting up a 3D structural model for the Lublin basin are presented. The Lublin basin has been an object of borehole- and seismic-based comprehensive geological studies for many years. The concepts about its structural style have been, however, widely varied throughout the years and there is still lack of consensus in this respect among researchers.

One of the first regional tectonic models of the area was by Żelichowski (1972), who postulated that the Lublin basin represented a tectonic graben and the tectonic style of the area was that of differentially subsided fault blocks. Pelc (1999) suggested a significant role of shale diapirism in producing the main regional structures (e.g. the Kock fault zone). A new tectonic model of the Lublin basin was proposed by Antonowicz et al. (2003). These authors interpreted the basin in terms of thin-skinned tectonics as a passive-roof syncline on top of aregional-size décollement. This concept was subsequently criticized by Dadlez (2003) and Narkiewicz (2003). Krzywiec & Narkiewicz (2003) proposed a transpressional origin for the structures in the Lublin basin and ascribed their formation to the Variscan orogeny. Results of our interpretations show the Devonian and Carboniferous strata to be cut by mostly NW–SE trending fault zones, composed of thrusts and backthrusts, often with steep attitude, locally defining classical triangle zones. Major thrust faults are accompanied by faultpropagation folds (locally of pop–up characteristics) and are rooted in a detachment in Silurian shale rocks. In the basin’s basement identified were high-angle major faults of NW–SE trend, in general throwing to the SW. The Kock fault zone is interpreted here as a major thrust fault detached in the Silurian shales, that propagated into Carboniferous coal-bearing strata, and that is located above a major normal fault in the basement. The SW margin of the Lublin basin represents a limb of a passive syncline which developed above a backthrust dipping to the NE. In its upper part the backthrust is locally cut by SW-dipping thrusts. Thereby, in our opinion, the structure of the Lublin basin does not have a characteristic of a simple tectonic graben. Instead, in the light of our analysis, it shows features of fold-and-thrust tectonics, albeit with moderate intensity of deformation, developed in a thin-skinned scenario. This interpretation confirms that the basin inversion occurred during the Variscan orogeny and is close to the ideas expressed earlier by Antonowicz et al. (2003). The seismic data interpreted in the frame of this research do not allow a critical assessment to be made of the idea of a strike-slip component of the motion on the NW–SE faults. Such a component is, however, likely and deserves further studies.

Antonowicz L., Hooper R. & Iwanowska E., 2003. Przegl. Geol., 51, 4, 344–350;

Dadlez R., 2003. Przegl. Geol., 51, 9, 729–730;

Krzywiec P., 2007. Biul. Państw. Inst. Geol., 422, 1–18 (in Polish with English summary);

Krzywiec P. & Narkiewicz M., 2003. Prz. Geol., 51, 9, 795–797;

Narkiewicz M., 2003. Przegl. Geol., 51, 9, 771–776;

Pelc T., 1999 Dewońsko-karboński diapiryzm sylurskich osadów ilastych basenu lubelskiego. V konferencja Naukowo-Techniczna “Geofizyka w geologii, górnictwie i ochronie środowiska”, 137–142, Kraków;

Żelichowski A.M., 1972. Biul. Inst. Geol., 263, 11–75