Organosulfur compounds: Molecular and isotopic evolution from biota to oil and gas

Alon Amrani*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

125 Scopus citations


Organosulfur compounds (OSCs) play important roles in the formation, preservation, and thermal degradation of sedimentary organic matter and the associated petroleum generation. Improved analytical techniques for S isotope analysis have recently enhanced our understanding of the mechanisms for OSC formation and maturation and their associated S isotope distributions. The close interaction of OSCs with inorganic S species throughout their formation and maturation affects their 34S/32S isotopic ratio (δ34S), forming specific signatures for distinct sources and processes. Ultimately, thermal maturation homogenizes the δ34S values of different fractions and individual compounds. Reservoir processes such as thermochemical sulfate reduction (TSR) introduce exogenous and isotopically distinct S into hydrocarbons and can significantly change the δ34S of petroleum or kerogen. Specific OSCs react at different rates and thus can be used to evaluate the extent of processes such as TSR. This article reviews factors that affect the 34S/32S isotopic distribution of OSCs along pathways of formation, diagenesis, and thermal alteration.

Original languageAmerican English
Pages (from-to)733-768
Number of pages36
JournalAnnual Review of Earth and Planetary Sciences
StatePublished - May 2014


  • Compound-specific sulfur isotope analysis
  • Organic-inorganic interactions
  • Sedimentary organic matter
  • Sulfur cycle
  • Thermochemical sulfate reduction


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