Constraining atmospheric oxygen and seawater sulfate concentrations during Paleoproterozoic glaciation: In situ sulfur three-isotope microanalysis of pyrite from the Turee Creek Group, Western Australia

Williford, Kenneth H.; Kranendonk, Martin J. Van; Ushikubo, T.; Kozdon, Reinhard; Valley, John W.

doi:10.1016/j.gca.2011.07.010

Cited by 92 publications

(83 citation statements)

References 81 publications

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“…In situ analyses of pyrite using SIMS have revealed striking heterogeneity for δ 34 S and Δ 33 S at the grain and subgrain scales (14,15), which has raised questions about the interpretation of bulk rock centimeter-scale analyses undertaken by SF 6 methods. The SIMS analyses presented here also reveal heterogeneity for δ 34 S and Δ…”

Section: Discussionmentioning

confidence: 99%

Pathways for Neoarchean pyrite formation constrained by mass-independent sulfur isotopes

Farquhar

Cliff

Zerkle

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

139

100

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It is generally thought that the sulfate reduction metabolism is ancient and would have been established well before the Neoarchean. It is puzzling, therefore, that the sulfur isotope record of the Neoarchean is characterized by a signal of atmospheric massindependent chemistry rather than a strong overprint by sulfate reducers. Here, we present a study of the four sulfur isotopes obtained using secondary ion MS that seeks to reconcile a number of features seen in the Neoarchean sulfur isotope record. We suggest that Neoarchean ocean basins had two coexisting, significantly sized sulfur pools and that the pathways forming pyrite precursors played an important role in establishing how the isotopic characteristics of each of these pools was transferred to the sedimentary rock record. One of these pools is suggested to be a soluble (sulfate) pool, and the other pool (atmospherically derived elemental sulfur) is suggested to be largely insoluble and unreactive until it reacts with hydrogen sulfide. We suggest that the relative contributions of these pools to the formation of pyrite depend on both the accumulation of the insoluble pool and the rate of sulfide production in the pyrite-forming environments. We also suggest that the existence of a significant nonsulfate pool of reactive sulfur has masked isotopic evidence for the widespread activity of sulfate reducers in the rock record.Neoarchean polysulfide production pathways | δ 34 S | Δ 33 S | Δ 36 S O ver the past 30 y, a significant amount of sulfur isotope data has been collected for sedimentary rocks and used as a way to study past atmospheric chemistry and biological activity. One feature of the sulfur isotope record that has been well-documented in the literature is a change from a relatively small range of variability for δ 34 S in Archean sediments to a larger range in younger sediments. Interpretations of the δ 34 S ½ð 34 S= 32 SÞ sample =ð 34 S= 32 SÞ V -CDT − 1 record have linked this pattern primarily to changes in the way that organisms metabolize sulfur. Experiments have shown that the magnitude of sulfur isotope fractionation diminishes as sulfate concentrations decrease (1). At low sulfate concentrations, sulfate reducers express only small fractionations, because the sulfate reduction metabolism operates as a nearly unidirectional chain of metabolic steps, and the isotope effects associated with each of the individual metabolic steps are not expressed in the final metabolic product (cf. 2). This microbial response to sulfate concentration has been invoked as the principle reason for the small range of δ 34 S observed early in the geologic record, suggesting that sulfate concentrations were lower in Earth's early oceans. It is not known if other factors also played a part in generating the small range of δ 34 S fractionations observed in the Neoarchean. We note that very large fractionations can occur at only slightly higher sulfate concentrations (1.1-2 mM) (3) and that the low concentration limit for generation of large fractionations associated ...

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Section: Discussionmentioning

confidence: 99%

Pathways for Neoarchean pyrite formation constrained by mass-independent sulfur isotopes

Farquhar

Cliff

Zerkle

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

139

100

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“…2.4 Ga because of greater iron solubility under reducing conditions (e.g., Rye and Holland, 1998); (3) the appearance of red beds after ca. 2.3 Ga (e.g., Roscoe, 1969;Chandler, 1980;Melezhik et al, 2005;Bankole et al, 2016); (4) the loss of S-MIF in sulfide and sulfate minerals in sedimentary rocks deposited after 2.3 Ga (Farquhar et al, 2000;Bekker et al, 2004;Papineau et al, 2007;Partridge et al, 2008;Guo et al, 2009;Williford et al, 2011;Luo et al, 2016;Gumsley et al, 2017); and (5) the increase in Cr and U contents in IF at 2.45 Ga that records the onset of oxidative continental weathering Partin et al, 2013a). anomaly (Alibert and McCulloch, 1993), suggesting a strong hydrothermal imprint on the REE systematics during its deposition, although, as noted above (Fig.…”

Section: Neoarchaean-palaeoproterozoic Iron Formationsmentioning

confidence: 91%

Iron formations: A global record of Neoarchaean to Palaeoproterozoic environmental history

Konhauser

Planavsky

Hardisty

et al. 2017

Earth-Science Reviews

382

257

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“…The thin Mn-enriched sedimentary bed has about 7% Mn and is constrained to be deposited between ca. 2420 Ma and 2209 Ma (Martin et al, 1998;Takehara et al, 2010;Williford et al, 2011; see SI for more details). Light and electron microscopy of the Kungarra manganese-rich bed show textures similar to the Koegas weathered samples that indicate Mn oxide replacements, and no EBSD pattern could be generated as the crystals are likely too small (Figs.…”

Section: Surface-weathered Depositsmentioning

confidence: 97%

Manganese mineralogy and diagenesis in the sedimentary rock record

Johnson

Webb

et al. 2016

Geochimica et Cosmochimica Acta

166

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Oxidation of manganese(II) to manganese(III,IV) demands oxidants with very high redox potentials; consequently, manganese oxides are both excellent proxies for molecular oxygen and highly favorable electron acceptors when oxygen is absent. The first of these features results in manganese-enriched sedimentary rocks (manganese deposits, commonly Mn ore deposits), which generally correspond to the availability of molecular oxygen in Earth surface environments. And yet because manganese reduction is promoted by a variety of chemical species, these ancient manganese deposits are often significantly more reduced than modern environmental manganese-rich sediments. We document the impacts of manganese reduction and the mineral phases that form stable manganese deposits from seven sedimentary examples spanning from modern surface environments to rocks over 2 billion years old. Integrating redox and coordination information from synchrotron X-ray absorption spectroscopy and X-ray microprobe imaging with scanning electron microscopy and energy and wavelength-dispersive spectroscopy, we find that unlike the Mn(IV)-dominated modern manganese deposits, three manganese minerals dominate these representative ancient deposits: kutnohorite (CaMn(CO 3 ) 2 ), rhodochrosite (MnCO 3 ), and braunite (Mn(III) 6 Mn(II)O 8 SiO 4 ). Pairing these mineral and textural observations with previous studies of manganese geochemistry, we develop a paragenetic model of post-depositional manganese mineralization with kutnohorite and calcian rhodochrosite as the earliest diagenetic mineral phases, rhodochrosite and braunite forming secondarily, and later alteration forming Mn-silicates.

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Constraining atmospheric oxygen and seawater sulfate concentrations during Paleoproterozoic glaciation: In situ sulfur three-isotope microanalysis of pyrite from the Turee Creek Group, Western Australia

Cited by 92 publications

References 81 publications

Pathways for Neoarchean pyrite formation constrained by mass-independent sulfur isotopes

Pathways for Neoarchean pyrite formation constrained by mass-independent sulfur isotopes

Iron formations: A global record of Neoarchaean to Palaeoproterozoic environmental history

Manganese mineralogy and diagenesis in the sedimentary rock record

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