Source rock habitat and hydrocarbon potential of Oligocene Menilite Formation (Flysch Carpathians, Southeast Poland): an organic geochemical and isotope approach

Geochemical and isotope methods have been used to analyse the hydrocarbon potential and petroleum generation characteristics of the Oligocene Menilite Formation, the most important petroleum source rock in the overthrust part of the Carpathian foreland basin in SE Poland. The data show a large variability in quantity (up to 18% TOC), quality (type II and II/III) and carbon isotope composition of the organic matter in samples of different lithology and from different stratigraphic and tectonic settings. These differences reflect distinct sedimentary and tectonic histories of individual sub-basins. The maturity in the outer tectonic units is very low (Tmax < 420°C, Ro < 0.35%) but increases towards the inner nappes and also laterally to the SE. The variability of the kinetic parameters indicates the likely occurrence of multiphase hydrocarbon generation. The Menilite Formation forms a very good source rock in the complex petroleum system of the Carpathian overthrust belt.