Biogenic gases were reported to exhibit a "normal" carbon isotope order of δ 13 C 1 <δ 13 C 2 <δ 13 C 3 <δ 13 C 4 , while abiogenic gaseous hydrocarbons in igneous rocks and meteorites exhibit a reversed distribution pattern in the order of δ 13 C 1 >δ 13 C 2 >δ 13 C 3 >δ 13 C 4 . This reversed order in carbon isotope compositions is commonly thought to be unique to abiogenic gases, thus it can be a criterion for determining their origins. In this study, a closed system Fischer-Tropsch synthesis was conducted at 380°C under 30MPa and 390°C under 30MPa, 100MPa, 200MPa, respectively, with magnetite as a catalyst. Results of carbon isotope compositions of gaseous hydrocarbons were derived, which do not show an expected reversed order in carbon isotope composition from C 1 to C 3 hydrocarbons, even though features of partially reversed order in carbon isotope values, such as δ 13 C 1 >δ 13 C 2 <δ 13 C 3 , can still be commonly observed. This indicates that the reversed order of carbon isotope composition is not a unique criterion that can be typically used to distinguish abiogenic gases. © 2012 Elsevier B.V.
Wei, Z., Zou, Y. R., Cai, Y., Tao, W., Wang, L., Guo, J., & Peng, P. (2012). Abiogenic gas: Should the carbon isotope order be reversed? Journal of Petroleum Science and Engineering, 84–85, 29–32. https://doi.org/10.1016/j.petrol.2012.01.019