title: Antiquity of the biological sulphur cycle: evidence from sulphur and carbon isotopes in 2700 million-year-old rocks of the Belingwe Belt, Zimbabwe.
abstract: Sulphur and carbon isotopic analyses on small samples of kerogens and sulphide minerals from biogenic and non-biogenic sediments of the 2.7 x 10(9) years(Ga)-old Belingwe Greenstone Belt (Zimbabwe) imply that a complex biological sulphur cycle was in operation. Sulphur isotopic compositions display a wider range of biological fractionation than hitherto reported from the Archaean. Carbon isotopic values in kerogen record fractionations characteristic of rubisco activity methanogenesis and methylotrophy and possibly anoxygenic photosynthesis. Carbon and sulphur isotopic fractionations have been interpreted in terms of metabolic processes in 2.7 Ga prokaryote mat communities, and indicate the operation of a diverse array of metabolic processes. The results are consistent with models of early molecular evolution derived from ribosomal RNA.
authors.affiliation: Department of Geology, Royal Holloway, University of London, Surrey, UK. nathalie@gl.rhbnc.ac.uk
authors.forename: N V
authors.initials: NV
authors.lastname: Grassineau
authors.forename: E G
authors.initials: EG
authors.lastname: Nisbet
authors.forename: M J
authors.initials: MJ
authors.lastname: Bickle
authors.forename: C M
authors.initials: CM
authors.lastname: Fowler
authors.forename: D
authors.initials: D
authors.lastname: Lowry
authors.forename: D P
authors.initials: DP
authors.lastname: Mattey
authors.forename: P
authors.initials: P
authors.lastname: Abell
authors.forename: A
authors.initials: A
authors.lastname: Martin
mesh_terms: D001105:Archaea / Q000378:metabolism*; D002247:Carbon Isotopes / Q000032:analysis*; D019015:Geologic Sediments / Q000382:microbiology*; D010163:Paleontology; D010788:Photosynthesis; D013455:Sulfur / Q000378:metabolism*; D013460:Sulfur Isotopes / Q000032:analysis*; D015030:Zimbabwe
chemical_list: D002247:Carbon Isotopes; D013460:Sulfur Isotopes; D013455:Sulfur