Petroleum geology of the Carpathian Foredeep and overthrust zones in the Czech Republic

The area is situated at the contact of two regional megastructures -the Bohemian Massif and the Western Carpathians. The eastern slope of the Bohemian Massif dips under the Carpathian Foredeep and thick Flysch nappes and is covered by Variscan and Neoidic autochthonous Palaeozoic, Mesozoic and Palaeogene sediments. In the southeast, the Vienna basin's Neogene fill overlies the units of the Magura Flysch and a part of the Zdanice unit. The area can be divided into three parts. The south is characterized by a thick Jurassic sedimentary complex that overlies the crystalline basement. The basal elastics of this Jurassic complex are very prospective and in the central part of the area the oil field Uhrice II is situated in these strata. In this central part two deep depressions - the Vranovice and Nesvacilka grabens - are the most important buried geomorphological elements. Both are filled with Palaeogene strata. The north of the area is characterized by uplifted crystalline basement with thin autochthonous sediments, mostly with Miocene strata of the foredeep and with the flysh nappes. Thick Palaeogene and Upper Jurassic pelites are supposed to be the main source rocks. The cap rocks are pelitic sequences of variable thicknesses including Jurassic marls, Palaeogene and Miocene claystones and basal claystones of flysch units. Traps are delimited by faults, lithology changes and unconformities.