Photochemical sulfurization of sedimentary organic matter: A widespread process occurring at early diagenesis in natural environments?

The possibility of light induced formation of sedimentary organo-sulfur compounds has been investigated with simulation experiments. These experiments, using mono-and diunsaturated hydrocarbons and reduced sulfur species, in particular H(2)S and elemental sulfur, were conducted under mild conditions (sunlight, low temperature) likely to occur in the photic zone of anoxic environments. These experiments showed an efficient sulphurization of the organic matter under sunlight conditions leading to the formation of organo-sulfur compounds, such as thiophenes and sulfur cross-linked macromolecules, very similar to those occurring in sediments deposited in anoxic environments. These results show the potential for photochemically induced sulfurization of organic matter in environments with photic zone anoxia. Such a process would be especially favored in evaporitic environments with a shallow anoxic boundary extending well into the photic zone. Copyright (C) 1998 Elsevier Science Ltd.