title: Productivity-induced sulphur enrichment of hydrocarbon-rich sediments from the Kimmeridge Clay Formation.
abstract: This work aims to highlight the relationship between primary productivity, sulphate reduction and organic carbon preservation in cyclic marine sediments from the Kimmeridge Clay Formation. A concomitant increase of the total sulphur content with the preserved organic content (TOC), shows the progressive supply of both metabolisable organic matter and resistant organic matter is linked to primary productivity. However, variations in sulphate reduction efficiency, based on elemental abundance and isotopic composition of sulphur, reveal that the proportion of metabolisable vs. resistant organic matter has varied along the cycles. This is interpreted in terms of the variation in organic delivery. Organic sulphur content is found to be proportional to the organic matter content, whereas concentrations of pyritic sulphur are constant at very high (> 10% TOC) values. This result is explained by a limitation of available iron for pyritisation at times of very high organic flux. Under such conditions, HS- in excess could be responsible for the early formation of organo-sulphur compounds and thus for the preservation of highly aliphatic (i.e. lipid-rich) organic matter.
authors.affiliation: URA 724-FR 09 CNRS, Universite d'Orleans, France.
authors.forename: E
authors.initials: E
authors.lastname: Lallier-Verges
authors.forename: J M
authors.initials: JM
authors.lastname: Hayes
authors.forename: M
authors.initials: M
authors.lastname: Boussafir
authors.forename: D A
authors.initials: DA
authors.lastname: Zaback
authors.forename: N P
authors.initials: NP
authors.lastname: Tribovillard
authors.forename: J
authors.initials: J
authors.lastname: Connan
authors.forename: P
authors.initials: P
authors.lastname: Bertrand
mesh_terms: D002244:Carbon / Q000032:analysis* / Q000737:chemistry*; D004739:England; D019015:Geologic Sediments / Q000032:analysis / Q000737:chemistry* / Q000382:microbiology; D006859:Hydrogen; D009659:North Sea; D010084:Oxidation-Reduction; D010839:Phytoplankton / Q000378:metabolism; D013455:Sulfur / Q000032:analysis* / Q000737:chemistry* / Q000378:metabolism; D013458:Sulfur Dioxide; D013460:Sulfur Isotopes; D016999:Sulfur-Reducing Bacteria / Q000378:metabolism
chemical_list: D013460:Sulfur Isotopes; D013458:Sulfur Dioxide; D013455:Sulfur; D002244:Carbon; D006859:Hydrogen