A Late Archean Sulfidic Sea Stimulated by Early Oxidative Weathering of the Continents

Reinhard, Christopher T.; Raiswell, R.; Scott, Clint; Anbar, Ariel D.; Lyons, Timothy W.

doi:10.1126/science.1176711

Cited by 237 publications

(242 citation statements)

References 29 publications

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“…3.5 Gyr), a simple sensitivity test of our mass-balance model demonstrates that such input flux variations should impart minimal influence on the [Re] sed record (SI). In general, our interpretation of atmosphere-ocean O 2 levels based on the Re record conforms well to that derived from the higherresolution Cr and U records (Partin et al, 2013;Reinhard et al, 2013a (Siebert et al, 2005;Anbar et al, 2007;Wille et al, 2007;Reinhard et al, 2009;Kendall et al, 2010Kendall et al, , 2015a.…”

Section: Temporal Trends In Re Concentrationssupporting

confidence: 88%

A model for the oceanic mass balance of rhenium and implications for the extent of Proterozoic ocean anoxia

Sheen

Kendall

Reinhard

et al. 2018

Geochimica et Cosmochimica Acta

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Emerging geochemical evidence suggests that the atmosphere-ocean system underwent a significant decrease in O 2 content following the Great Oxidation Event (GOE), leading to a mid-Proterozoic ocean (ca. 2.0-0.8 Ga) with oxygenated surface waters and predominantly anoxic deep waters. The extent of mid-Proterozoic seafloor anoxia has been recently estimated using mass-balance models based on molybdenum (Mo), uranium (U), and chromium (Cr) enrichments in organic-rich mudrocks (ORM). Here, we use a temporal compilation of concentrations for the redox-sensitive trace metal rhenium (Re) in ORM to provide an independent constraint on the global extent of mid-Proterozoic ocean anoxia and as a tool for more generally exploring how the marine geochemical cycle of Re has changed through time. The compilation reveals that mid-Proterozoic ORM are dominated by low Re concentrations that overall are only mildly higher than those of Archean ORM and significantly lower than many ORM deposited during the ca. 2.22-2.06 Ga Lomagundi Event and during the Phanerozoic Eon. These temporal trends are consistent with a decrease in the oceanic Re inventory in response to an expansion of anoxia after an interval of increased oxygenation during the Lomagundi Event. Mass-balance modeling of the marine Re geochemical cycle indicates that the mid-Proterozoic ORM with low Re enrichments are consistent with extensive seafloor anoxia. Beyond this agreement, these new data bring added value because Re, like the other metals, responds generally to lowoxygen conditions but has its own distinct sensitivity to the varying environmental controls. Thus, we can broaden our capacity to infer nuanced spatiotemporal patterns in ancient redox landscapes. For example, despite the still small number of data, some mid-Proterozoic ORM units have higher Re enrichments that may reflect a larger oceanic Re inventory during transient episodes of ocean oxygenation. An improved understanding of the modern oceanic Re cycle and a higher temporal resolution for the Re compilation will enable further tests of these hypotheses regarding changes in the surficial Re geochemical cycle in response to variations in atmosphere-ocean oxygenation. Nevertheless, the existing Re compilation and model results are in agreement with previous Cr, Mo, and U evidence for pervasively anoxic and ferruginous conditions in mid-Proterozoic oceans.

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Section: Temporal Trends In Re Concentrationssupporting

confidence: 88%

A model for the oceanic mass balance of rhenium and implications for the extent of Proterozoic ocean anoxia

Sheen

Kendall

Reinhard

et al. 2018

Geochimica et Cosmochimica Acta

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“…McRae Shale in Western Australia, recording transient oxidised conditions now widely known as the 'whiff' of oxygen (Anbar et al, 2007). The whiff is recorded by spikes in Mo and Re concentrations, elevated nitrogen isotope values, and iron speciation data (Anbar et al, 2007;Reinhard et al, 2009;Garvin et al, 2009); based on Re-Os isotope analyses, these data can be confidently considered primary signals (Kendall et al, 2015). The shales lie near the middle of the 2. .…”

Section: Iron Formations Primary Productivity and Atmospheric Oxygementioning

confidence: 99%

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

Konhauser

Planavsky

Hardisty

et al. 2017

Earth-Science Reviews

335

247

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“…As a result, in an ocean that is pervasively reducing and Fe 2+ -buffered we would expect that the partitioning of relative sulphur burial between continental margin and deep-sea settings will roughly track relative differences in primary and export production. In fact, marginal settings where carbon fluxes are locally much higher are much more likely to be characterized by Fe-limited pyrite formation 68,69 , and sulphur burial in such settings would thus be relatively inefficient.…”

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confidence: 99%

“…(4) that small inputs of solubilized sulphur from the weathering crust as a result of low-level oxidative processing (e.g., ref. 40,68,[78][79][80] could potentially act to greatly amplify any isotopic asymmetry initialized as described above.…”

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confidence: 99%

Long-term sedimentary recycling of rare sulphur isotope anomalies

Reinhard

Planavsky

Lyons

2013

Nature

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Sulphur Isotope Database:An extensive sulphur isotope database was used in the construction of Main Text Figure 1. These data were compiled from primary references 1-37 , although in some cases age constraints for certain units were obtained from other sources [38][39][40][41] or estimated. For Main Text Figure 1b, we calculated the cumulative average ∆ 33 S value for all samples up to each year of publication. The average values reported here thus include some contribution from sulphate minerals. However, the overwhelming majority of the data are sulphide mineral phases, and given that most sulphate data are characterized by negative ∆ 33 S values their inclusion will largely attenuate the pattern emphasized here, rendering our argument conservative. Furthermore, the overall effect of their inclusion is quite small (Fig. S1a,b). We also examined the effect of filtering data from analyses made via secondary ion mass spectrometry (SIMS) and analyses of macroscopic pyrite textures, which are not likely to be representative of bulk weathering crust, but again note that the basic pattern remains unchanged (Fig. S1a,b).The mean ∆ 33 S values shown in Fig. 1 are presented as unweighted averages. We consider this approach qualitatively justified, in that the database is composed largely of fine-grained siliciclastic sedimentary rocks that are relatively organic carbon and sulphur rich. Such rocks will not only be, on average, the most sulphur-enriched phases of the crust, but they will also likely hold the majority of the weathering sulphur reservoir at Earth's surface. Nonetheless, it is important to consider the possibility that there is a bias related to systematic relationships between the sulphur content of sedimentary rocks and their ∆ 33 S value. For this purpose, we compiled the available sulphur concentration data for the units within the isotope database and performed concentration-weighted statistical analyses.There does not appear to be any systematic relationship between rare sulphur isotope composition and sulphur content within the database (Fig. S2a). In addition, the cumulative unweighted average is nearly indistinguishable from the concentration-weighted average within this subset of the database (Fig. S2a,b). When the evolution of the overall ∆ 33 S value of the database is concentration-weighted, it shows a generally similar pattern through time to that of the overall mean values (Fig. S2b). Indeed, the mean ∆ 33 S value when weighted by concentration is more positive than the unweighted mean for a given population from the database. We stress the caveat that many of the published rare sulphur isotope datasets do not contain sulphur concentration data, so unfortunately this analysis cannot be performed on the entire database. However, the coupled isotope and concentration data represent well over 500 samples that range in sulphur content over three orders of magnitude. These considerations lead us to conclude that the pattern expressed in the overall mean ∆ 33 S values through time is robust and is ...

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A Late Archean Sulfidic Sea Stimulated by Early Oxidative Weathering of the Continents

Cited by 237 publications

References 29 publications

A model for the oceanic mass balance of rhenium and implications for the extent of Proterozoic ocean anoxia

A model for the oceanic mass balance of rhenium and implications for the extent of Proterozoic ocean anoxia

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

Long-term sedimentary recycling of rare sulphur isotope anomalies

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