Carbon dating crude oil
NEWS RELEASE 08/04/94 CONTACT: Stanford University News Service (650) 723-2558 STANFORD -- The Jurassic (180 million to 140 million years ago) was a very good age for oil formation.
So too was the Cretaceous (140 million to 65 million years ago).
If it contains large amounts of the organic substance, on the other hand, its pedigree most likely dates from the post-Cretaceous or Tertiary Age (65 million to 5 million years ago).
Because the geological processes involved convert the oleanoids in the angiosperms into oleanane, the more oleanane found in a given oil sample, the more recent it is likely to be. Oils of any age can lack oleanane if flowering plants were not part of the material from which it formed.
But lack of oleanane is a significant clue that the oil may have formed in the Jurassic or older times, before angiosperms evolved.
Notice in the diagram that eight different isotopes of Carbon are illustrated.
Three of the Carbon isotopes (C) are found in nature.