Investigating sulfur pathways through the lithosphere by tracing mass independent fractionation of sulfur to the Lady Bountiful orogenic gold deposit, Yilgarn Craton

Crystal LaFlamme, John W. Jamieson, Marco L. Fiorentini, Nicolas Thébaud, Stefano Caruso, Vikraman Selvaraja

    Research output: Contribution to journalReview article

    21 Citations (Scopus)

    Abstract

    As sulfur is the primary complexing ligand for gold transport in aqueous fluids, recent work has demonstrated that the Archean systems can preserve mass independent fractionation of sulfur (MIF-S) to yield near-zero values (Δ33S1 = 0 ± 0.5‰). In such cases, interpretation of the geological significance of such isotopic signatures may be compromised as it is known that mass dependent fractionation of sulfur (MDF-S) can yield small Δ33S values (herein as Δ33SB) often owing to geobiological reactions involving sulfur. In this study, we reassess the range of possible values of Δ33SB from the traditionally accepted value of 0 ± 0.2‰, to demonstrate that this range is not constant but rather directly linked to the degree of δ34S fractionation. We present a multiple sulfur isotope dataset from the Neoarchean Lady Bountiful orogenic gold deposit from the Yilgarn Craton, Western Australia. This deposit contains pyrite with an isotopic composition of δ34S = ~+2.1 ± 0.8‰ and Δ33S = +0.14 ± 0.06‰ (2SD on the mean). The analysis of these results, as well as of a data compilation from other ~2.65 Ga orogenic gold deposits of the Yilgarn Craton, indicates that Δ33S1 values are too large to be the result of purely MDF-S processes. In addition, when compared to a compilation of >3400 Δ33S0 measurements of Archean sedimentary rocks, which shows highly variable positive and negative signals, the remarkably constant positive MIF-S1 signature of gold deposits from the Yilgarn Craton, with Δ33S1 values between 0 and +0.6‰, is evidence that the source of the auriferous fluids equilibrated at depth by mixing with a non MIF-S0-bearing sulfur reservoir. By enhancing the application of MIF-S133S1) as a powerful and indelible tracer to understand the source and emplacement pathways of gold-bearing fluids through the lithosphere, the outcomes from this study demonstrate the recorded +Δ33S1 signature in the auriferous fluids reflects the presence of sulfur that was at least partially sourced from an Archean sediment reservoir.

    Original languageEnglish
    Pages (from-to)27-38
    Number of pages12
    JournalGondwana Research
    Volume58
    DOIs
    Publication statusPublished - 1 Jun 2018

    Fingerprint Dive into the research topics of 'Investigating sulfur pathways through the lithosphere by tracing mass independent fractionation of sulfur to the Lady Bountiful orogenic gold deposit, Yilgarn Craton'. Together they form a unique fingerprint.

    Cite this