Multiple Sulfur Isotope Analyses Support a Magmatic Model for the Volcanogenic Massive Sulfide Deposits of the Teutonic Bore Volcanic Complex, Yilgarn Craton, Western Australia

Abstract

We report sensitive high mass resolution ion microprobe, stable isotopes (SHRIMP SI) multiple sulfur isotope analyses ( 32 S, 33 S, 34 S) to constrain the sources of sulfur in three Archean VMS deposits-Teutonic Bore, Bentley, and Jaguar-from the Teutonic Bore volcanic complex of the Yilgarn Craton, Western Australia, together with sedimentary pyrites from associated black shales and interpillow pyrites. The pyrites from VMS mineralization are dominated by mantle sulfur but include a small amount of slightly negative mass-independent fractionation (MIF) anomalies, whereas sulfur from the pyrites in the sedimentary rocks has pronounced positive MIF, with ∆ 33 S values that lie between 0.19 and 6.20‰ (with one outlier at -1.62‰). The wall rocks to the mineralization include sedimentary rocks that have contributed no detectable positive MIF sulfur to the VMS deposits, which is difficult to reconcile with the leaching model for the formation of these deposits. The sulfur isotope data are best explained by mixing between sulfur derived from a magmatic-hydrothermal fluid and seawater sulfur as represented by the interpillow pyrites. The massive sulfide lens pyrites have a weighted mean ∆ 33 S value of -0.27 ± 0.05‰ (MSWD = 1.6) nearly identical with -0.31 ± 0.08‰ (MSWD = 2.4) for pyrites from the stringer zone, which requires mixing to have occurred below the sea floor. We employed a twocomponent mixing model to estimate the contribution of seawater sulfur to the total sulfur budget of the two Teutonic Bore volcanic complex VMS deposits. The results are 15 to 18% for both Teutonic Bore and Bentley, much higher than the 3% obtained by Jamieson et al. (2013) for the giant Kidd Creek deposit. Similar calculations, carried out for other Neoarchean VMS deposits give value between 2% and 30%, which are similar to modern hydrothermal VMS deposits. We suggest that multiple sulfur isotope analyses may be used to predict the size of Archean VMS deposits and to provide a vector to ore deposit but further studies are needed to test these suggestions.

In situ multiple sulfur isotope analysis by SIMS of pyrite, chalcopyrite, pyrrhotite, and pentlandite to refine magmatic ore genetic models

“…As such, intra-grain and inter-grain chemical and isotopic variations in sulfurrich mineralised systems record the interaction of these different reservoirs and offer unique insights into the complex fluid-rock interactions within mineral systems (McCuaig et al 2010). For example, in magmatic ore deposits, sulfur isotope data have fingerprinted the source of the sulfur linked to ore genesis (Bekker et al, 2009;Chang et al, 2008;Fiorentini et al, 2012a;Hiebert et al, 2013;Lesher and Groves, 1986;Penniston-Dorland et al, 2008;Sharman et al, 2013) and constrained the geodynamic framework where these deposits formed (e.g., Chen et al, 2015;Fiorentini et al, 2012b;Giacometti et al, 2014). Similarly, sulfur isotope studies have proven to be vital in characterising magmatic-hydrothermal (Helt et al, 2014;Xue et al, 2013) and hydrothermal systems (e.g., Jamieson et al, 2013;Leach et al, 2005;Sharman et al, 2015).…”

A small S-MIF signal in Martian regolith pyrite: Implications for the atmosphere

“…The high Ni contents of some pyrite grains is also consistent with sulfidation of pentlandite-bearing pyrrhotite, which is common in shergottites. This sort of scenario is similar in some ways to the dampened S-MIF signal seen in hydrothermal volcanogenic sulfide systems in Archean Earth rocks, in which modest proportions of atmospheric S contribute to the overall budget (Jamieson et al, 2013;Chen et al, 2015). A schematic representation of the position of NWA 7034 and pairs in the context of the above discussion is shown in Figure 6.…”

Extreme enrichment of selenium in the Apliki Cyprus-type VMS deposit, Troodos, Cyprus

“…Se, Te, Cu, Bi, Co etc. (de Ronde et al ., 2011; Chen et al , 2015; Melekestseva et al , 2017; Sillitoe et al , 1996). The δ 34 S values for most Mid Ocean Rdige and back-arc VMS sulfides falls within a narrow range of 0 to 5‰ δ 34 S. The narrow range reflects the mixing of magmatic sourced sulfur (0‰, Vibetti, 1993) and sulfur derived from seawater sulfate reduction (+20.7‰, Herzig et al , 1998; Vibetti, 1993).…”