Gas chromatography and gas chromatography—mass spectrometry study of hydrocarbons in vlasta oil (adriatic basin) as the basis for geochemical interpretation

Abstract In order to elucidate the chemistry and geochemistry of vlasta oil (central Adriatic Basin) a gas chromatography and gas chromatography—mass spectrometry study of hydrocarbon composition and structure was performed, as well as some global geochemical characterization. Twenty-one components of the light end of the oil, 83 components of the whole-oil sample and 17 components of the heavy end of the oil were identified by gas chromatography and by a gas chromatography—mass spectrometry coupled system. The light components are represented by straight and branched alkanes, cycloalkanes and aromatics, whereas thioethers are found to be whole-oil components. The heavy components are represented by pentacyclic triterpanes. The obtained results have shown algal and bacterial biomass to be the most probable origin of the Vlasta oil, which was deposited in anoxic hypersaline in carbonate beds during the Triassic period. Oil was released from related kerogen in the early stage of maturity. It underwent no significant biodegradation.