Multiple sulphur and iron isotope composition of detrital pyrite in Archaean sedimentary rocks : a new tool for provenance analysis
Rouxel, Olivier J.
MetadataShow full item record
KeywordArchaean; Witwatersrand basin; Belingwe greenstone belt; S isotope; Fe isotope; Pyrite; Gold mineralisation
Multiple S (δ34S and δ33S) and Fe (δ56Fe) isotope analyses of rounded pyrite grains from 3.1 to 2.6 Ga conglomerates of southern Africa indicate their detrital origin, which supports anoxic surface conditions in the Archaean. Rounded pyrites from Meso- to Neoarchaean gold and uranium-bearing strata of South Africa are derived from both crustal and sedimentary sources, the latter being characterised by non-mass dependent fractionation of S isotopes (Δ33S as negative as -1.35‰) and large range of Fe isotope values (δ56Fe between -1.1 and 1.2‰). Most sediment-sourced pyrite grains are likely derived from sulphide nodules in marine organic matter-rich shales, sedimentary exhalites and volcanogenic massive sulphide deposits. Some sedimentary pyrite grains may have been derived from in situ sulphidised Fe-oxides, prior to their incorporation into the conglomerates, as indicated by unusually high positive δ56Fe values. Sedimentary sulphides without significant non-mass dependent fractionation of S isotopes were also present in the source of some conglomerates. The abundance in these rocks of detrital pyrite unstable in the oxygenated atmosphere may suggest factors other than high pO2 as the cause for the absence of significant non-mass dependent fractionation processes in the 3.2 – 2.7 Ga atmosphere. Rounded pyrites from the ca. 2.6 Ga conglomerates of the Belingwe greenstone belt in Zimbabwe have strongly fractionated δ34S, Δ33S and δ56Fe values, the source of which can be traced back to black shale-hosted massive sulphides in the underlying strata. The study demonstrates the utility of combined multiple S and Fe isotope analysis for provenance reconstruction of Archaean sedimentary successions.
Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Earth and Planetary Science Letters 286 (2009): 436-445, doi:10.1016/j.epsl.2009.07.008.
Suggested CitationPreprint: Hofmann, Axel, Bekker, Andrey, Rouxel, Olivier J., Rumble, Douglas, Master, Sharad, "Multiple sulphur and iron isotope composition of detrital pyrite in Archaean sedimentary rocks : a new tool for provenance analysis", 2009-06-29, https://doi.org/10.1016/j.epsl.2009.07.008, https://hdl.handle.net/1912/3068
Showing items related by title, author, creator and subject.
Observations of Li isotopic variations in the Trinity Ophiolite : evidence for isotopic fractionation by diffusion during mantle melting Lundstrom, Craig C.; Chaussidon, Marc; Hsui, Albert T.; Kelemen, Peter B.; Zimmerman, Mark (2004-08-10)The Trinity peridotite (northern CA) contains numerous lithologic sequences consisting of dunite to harzburgite to spinel lherzolite to plagioclase lherzolite. Previous workers have documented geochemical gradients in these ...
Revising estimates of aquatic gross oxygen production by the triple oxygen isotope method to incorporate the local isotopic composition of water Manning, Cara C.; Howard, Evan M.; Nicholson, David P.; Ji, Brenda Y.; Sandwith, Zoe O.; Stanley, Rachel H. R. (John Wiley & Sons, 2017-10-25)Measurement of the triple oxygen isotope (TOI) composition of O2 is an established method for quantifying gross oxygen production (GOP) in natural waters. A standard assumption to this method is that the isotopic composition ...
Assessing the blank carbon contribution, isotope mass balance, and kinetic isotope fractionation of the Ramped Pyrolysis/Oxidation instrument at NOSAMS Hemingway, Jordon D.; Galy, Valier; Gagnon, Alan R.; Grant, Katherine E.; Rosengard, Sarah Z.; Soulet, Guillaume; Zigah, Prosper; McNichol, Ann P. (2017-03)We estimate the blank carbon mass over the course of a typical Ramped PyrOx (RPO) analysis (150 to 1000 °C; 5 °C×min-1) to be (3.7 ± 0.6) μg C with an Fm value of 0.555 ± 0.042 and a δ13C value of (-29.0 ± 0.1) ‰ VPDB. ...