Boreham C J, Fookes C J, Popp B N, Hayes J M
Division of Continental Geology, BMR, Canberra, Australia.
Geochim Cosmochim Acta. 1989;53:2451-5. doi: 10.1016/0016-7037(89)90368-2.
In samples of the Julia Creek and Condor oil shales (Australia, Albian, and early Tertiary, respectively) etioporphyrin III is significantly depleted in 13C (4%) relative to porphyrins derived from chlorophylls. This isotopic difference suggests a large contribution from some independent source. The haem group found in cytochromes derived from microbial sources is the most likely candidate.
