The vanadium isotopic constitution of petroleum asphaltenes: La Luna Formation (Venezuela)

High resolution mass spectrometry indicates that the isotopic abundance of 50vanadium (V) of the Late Cretaceous La Luna petroleum asphaltenes and related source kerogen of marine origin (both highly enriched with V >> 2000 ppm) is higher by about 3,5 % than that of an inorganic vanadium source (VOSO4 > 5H2O, Merck). It is proposed that the difference in the 50V/51V values between the La Luna source kerogen/the associated petroleum asphaltenes and the inorganic source can be best ascribed to the biological processing of seawater V. The fact that the isotopic compositions of V vary over a very narrow range (2.46-2.50) suggest an essentially same (or similar) and fixed bilogical source of V.