Journal of Petroleum Geology, Vol.4, No.4, pp. 437-439, 1982
©Copyright 2000 Scientific Press, Ltd.
EVIDENCE THAT STABLE CARBON ISOTOPES ARE NOT A
RELIABLE CRITERION FOR DISTINGUISHING BIOGENIC FROM NON-BIOGENIC PETROLEUM
A. A. Giardini* and Charles E. Melton**
Departments of Geology* and Chemistry**, University of
Georgia, Athens, GA, 30602, USA.
The isotopic abundance of presumably-pristine primordial carbon has
been determined by analyzing carbon dioxide entrapped in a 8.65 carat natural diamond of
African origin. The results were 12C = 98.9275% and 14C = 1.0725%, which give 13C = -35.2 0/00.
This value is well within the range used to assign a biogenic origin to carbon-containing
compounds, i.e., more negative than -18.0 0/00. Similar negative values have been reported for some natural diamonds and
carbon-bearing meteorites. It is concluded, therefore, that stable carbon isotopes can be
an unreliable criterion for assigning a biogenic origin to petroleum.