Petroleum biological origin

A biological marker (or "biomarker") may be defined as "a compound the structure of which can be interpreted in terms of a previous biological origin." Since the isolation and identification of metalloporphyrins in bitumens by Treibs (2) in the 1930 s and their correlation with tetrapyrroles of chlorophylls. Implying a biological origin for petroleum, an enormous amount of progress has been accomplished in this area of research. 

The major metalloporphyrin in petroleum and oil shale is vanadyl deoxo-phylloerythroetioporphyrin (VODPEP) which was first discovered by Alfred Treibs (of the same Munich school of porphyrin chemistry as Hans Fischer) in 1934. Treibs quickly realised that his discovery strongly implied a biological origin for coal and oil. But he went further and developed a scheme of chemical (as opposed to biochemical) reactions that could have occurred to convert chlorophyll in green plants into VODPEP. 

Some of the molecules in petroleum are clearly of biological origin. Most scientists believe that petroleum originated with accumulation of dead microorganisms that settled to the bottom of the sea and that were entombed in sedimentary rock. These microbial remains eventually were transformed into oil by the heat radiating from Earth s core. 

Mei.ezhik Fallick (2000) Melezhik, V Fallick, A. Isotopic evidence for biological origin of shungite, generation of petroleum and 13C depleted nature of initial biomass at 2.0Ga ago Journal of Conference Abstracts - Goldschmidt 2000 5 2 (2000) 701... 

Petroleum or crude oil is a naturally occurring complex mixture, composed mainly of hydrocarbons. Although there are, without any doubt, numerous compounds that have been formed directly from biologically produced molecules, the majority of petroleum components are of secondary origin, either decomposition products or products of condensation and polymerization reactions. 

Schoell M (1984) Recent advances in petroleum isotope geochemistry. Org Geochem 6 645-663 Schoell M (1988) Multiple origins of methane in the Earth. Chem Geol 71 1-10 Schoell M, McCaffrey MA, Fago FJ, Moldovan JM (1992) Carbon isotope compositions of 28,30-bisnorhopanes and other biological markers in a Monterey crude oil, Geochim Cosmochim Acta 56 1391-1399... 

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