Discussion on the studies of position-specific carbon isotopes of propane by Li et al. (2018), Zhang et al. (2022) and Shuai et al. (2023)

Abstract

In a series of recent publications in Organic Geochemistry and elsewhere, investigators from State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry and their collaborators have reported position-specific δ13C of propane obtained from natural reservoirs and pyrolysis experiments. Based solely on the very negative ΔC-T values (δ13Ccenter – δ13Cterminal), ranging from −7 to −10 ‰, they advocated for abiogenic origins of the propanes from sedimentary settings (shale and coal deposits). However, they never demonstrated accuracy of the data and it is likely that correct ΔC-T values for these propanes are close to zero ‰. Therefore, their discussion and interpretation in terms of geochemical processes, including a putative abiogenic origin, are not substantiated.