Hydrocarbons migration in tectonic zones of the Western Tatra Mountains crystalline basement (Central Western Carpathians)

In the Western Tatra Mountains crystalline basement a bituminous matter was found in tectonic zones (faults, shatter zones). The tectonic zones run NE -SW cutting both the Variscan crystalline basement and its sedimentary Meso zoic cover. Oxyreactive Thermal Analyses of whole rock samples and Gas Chro matography-Mass Spectroscopy analyses of extractable organic matter reveale d that the bitumens in question are heavy fractions of crude oils. The sour ce rocks of the bitumens were marine shales and lacustrine sediments, relat ively poor in organic material, accumulated in suboxic shelf conditions. Th e thermal maturity of the bitumens was determined as the oil-window stage ( R-CS = 0.74-0.82 %). The terrestrial organic matter admixture was negligibl y small, so we can suggest the age of the source material may be older than Tertiary (by comparison with the other Carpathian oils). The comparison wi th the Outer Carpathian crude oils showed that the Western Tatra bitumens r esemble Jurassic oils more than Paleogene ones. Jurassic and Upper Triassic carbonates and black shales from the overthrust Tatricum sequences seem to be a more plausible source rocks for the investigated bitumens. The tecton ic zones, rejuvenated after or during Miocene uplift of the Tatra Block ser ved as the paths for bitumens migration.