Carbon Isotope and Biogenic Provenance Issues

The late Jack Kenny argued that carbon isotopes could not be used as a determinant of whether a substance had a biological origin or provenance and one of the lines of evidence used was the measured isotopic ratio of carbon 12/13 in a primeval diamond reported by Giardini et al 1982.

In that report it was shown that the carbon isotope ratio of the diamond, compared to the Pee Dee Belemnite standard was -35.2%. Pee Dee Belemnite standard ratios more negative than -18% are indicative of a biological origin. On this basis and from the dating of the particular diamond which indicated an age crystallisation of 3.1 x 10^9 years, “well before any record of biological life on Earth”, it was concluded that carbon isotope (C12/13) ratios can’t be used to determine a biogenic provenance.

Not so, because while the carbon isotope ratio is the result of measurement and calculation, the statement that there was no biological life on the Earth is not a fact but a belief, an imaginary construct.

Rather the empirical procedure is to conclude that this particular diamond had a biogenic origin or provenance and that the belief of life not existing at the time is actually wrong; clearly life was present 3.1 x 10^9 years ago as indicated by the data.

So it is quite likely that petroleum is biogenic AND derived from the mantle.

(reference: Giardini, A. A., Melton, C.E., Mitchell, R.S., (1982), J Pet. Geo., 5, 2, 173-190)

About Louis Hissink

Retired diamond exploration geologist. I spent my professional life looking for mineral deposits, found some, and also located a number of kimberlites in NSW and Western Australia. Exploration geology is the closest one can get to practicing the scientific method, mineral exploration always being concerned with finding anomalous geophysical or geochemical data, framing a model and explanation for the anomaly and then testing it with drilling or excavation. All scientific theories are ultimately false since they invariably involved explaining something with incomplete extant knowledge. Since no one is omniscient or knows everything, so too scientific theories which are solely limited to existing knowledge. Because the future always yields new data, scientific theories must change to be compatible with the new data. Thus a true scientist is never in love with any particular theory, always knowing that when the facts change, so too must he/she change their minds.
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