Print this pageBiomarkers and Carbon Isotopes of Oils and Natural Bitumens in the Precambrian and Paleozoic-Mesozoic Formations of the Siberian Plafform, Russia.
KASHIRTSEV, VLADIMIR. A., and PHILP R. PAUL
The oil and tar sand samples have been examined by a number of geochemical techniques including gas chromatography, gas chromatographymass spectrometry and stable isotope mass spectrometry. The oils and bitumens represent various geologic ages (from Vendian to Jurassic) and depositional environments of source rocks. The Vendian and Low Cambrian oils and bitumens from NepaBotuobian and Lena-Anabarian basins had a lightest carbon isotopic values (delta{13}C around -32 to -34%) whereas the Permian-Jurassic oils and bitumens from Vilyuian and Lena-Anabarian basins were the heaviest in the -25 to -28% region.
The n-alkane, isoalkane, terpane and sterane distributions of the oils and tar sand bitumens from the three basins could be used to differentiate the oils and bitumens on the six various families on the basis of difference in source materials and depositional environments.
Although the Low Cambrian and Permian tar sand bitumens from Lena-Anabarian basin have been severely biodegraded and most of the nalkanes and isoprenoid alkanes have been removed and the hopanes altered to 25-norhopanes, that various families can be distinguished on basis the diasterane distributions and stable isotopic composition.