Marek Wojdyla1, Radoslaw Florek2, Cezary Ostrowski1, Janusz Siupik2, Michal Stefaniuk1, and Pawel Targosz1
1PBG Geophysical Exploration Company, Warsaw, Poland
2Polish Oil and Gas Company, Poland
The Outer Carpathians are a zone of very complex tectonics formed by intense folding, faulting and overthursting. Recognizing the sub-orogenic basement is difficult as complex structure of the flysch cover lowers the efficiency of the reflection seismic method. Therefore, the magnetotelluric and gravity methods were used to support seismic data interpretation and constrain objects to detailed geophysical recognition. As a result of the complex interpretation, a geological model of the Carpathian basement was proposed. Based on MT data interpretation, structural outlines of major high–resistivity horizons i.e. the sub-Miocene basement and the top of carbonate Upper Devonian and Lower Carboniferous complex and the top of crystalline Precambrian basement and low-resistivity complexes of the Upper Permian and Triassic and Lower Paleozoic sediments were obtained. As a result of comprehensive interpretation of MT and gravity data, a geological cross-section and tectonic scheme with fault zones were obtained. Maps of maximum gravity field horizontal gradients and resistivity distribution at depth slices were used to recognize and interpret tectonic boundaries. The sub-Miocene basement is cut by at least two regional strike-slip fault zones with NW-SE and SW-NE directions. The faults are possible elements of major regional tectonic zones. Minor faults occurring between major faults divide the area into several tectonic blocks. Geological cross-sections were obtained based on 1D/2D interpretation of magnetotelluric data and 2D gravity modelling and show the relations between the Carpathian overthrust and autochthonous Miocene and sub-Miocene basement.
AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece