Ocean stagnation and ventilation defined by δ34S secular trends in pyrite and barite, Selwyn Basin, Yukon

Goodfellow, Wayne D.; Jonasson, I R

doi:10.1130/0091-7613(1984)12<583:osavdb>2.0.co;2

Cited by 99 publications

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“…The sulfur isotope data for pyrite determined using SIMS starkly contrast previously published data for bulk analyses of pyrite separates (Table 1; Goodfellow and Jonasson 1984;Goodfellow 1987). These differences between SIMS and bulk sample data may be explained by one or more of the following: (1) the presence of finely intergrown, texturally complex pyrite of multiple generations (Fig.…”

Section: Discussioncontrasting

confidence: 50%

“…Biogenic sulfide has also been implicated as the predominant source of sulfur for base-metal sulfides of the HPD (Goodfellow and Jonasson 1984;Goodfellow 1987;Turner 1992;Goodfellow et al 1993); however, the contribution of BSR sulfur to Zn-Pb mineralization is not obvious here because all of the sphalerite, galena, and nonframboidal pyrite have positive (≫ 0 ‰) δ 34 S values. Goodfellow (1987) proposes that these positive values are related to long-term, persistent (ca.…”

mentioning

confidence: 88%

“…δ 34 S determinations were performed by bombarding the sample with a primary ion microbeam of 350-450 pA of Cs + , accelerated through a 10-keV potential, and focused into a 5-15-μm diameter spot. To exclude exotic material in the polished surface from analysis, each spot was first presputtered for 120-150 s with a 25-μm-wide square Goodfellow and Jonasson (1984) raster applied to the beam. Depending on the minimum diameter of the critically focused primary beam during each session, a smaller square raster (5 to 15 μm wide) was applied to the beam during analysis, to improve the homogeneity of primary ion delivery (Brueckner et al 2015 S 0.2 ‰) at the beginning of and throughout each day.…”

Section: Sediment-hosted Zn-pb Depositsmentioning

confidence: 99%

“…A common feature of the Selwyn Basin deposits is the finegrained nature of the sulfide minerals, and pyrite is a ubiquitous component of the mineralized zones and host rocks in all of these districts (e.g., Goodfellow and Jonasson 1984;Goodfellow 1987;Morganti 1979;. These studies focused on the sulfur isotope composition of sulfide minerals at the mineral grain scale to elucidate the source(s) of sulfur for sulfide precipitation and massive sulfide formational processes.…”

Section: Introductionmentioning

confidence: 99%

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The world-class Howard’s Pass SEDEX Zn-Pb district, Selwyn Basin, Yukon. Part II: the roles of thermochemical and bacterial sulfate reduction in metal fixation

et al. 2016

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The Howard's Pass district of sedimentary exhalative (SEDEX) Zn-Pb deposits is located in Yukon Territory and comprises 14 Zn-Pb deposits that contain an estimated 400.7 Mt of sulfide mineralization grading 4.5 % Zn and 1.5 % Pb. Mineralization is hosted in carbonaceous and calcareous and, to a lesser extent, siliceous mudstones. Pyrite is a minor but ubiquitous mineral in the host rocks stratigraphically above, within, and below mineralization. Petrographic analyses reveal that pyrite has a complex and protracted growth history, preserving multiple generations of pyrite within single grains. Sulfur isotope analysis of paragenetically complex pyrite by secondary ion mass spectrometry (SIMS) reveals that sulfur isotope compositions vary with textural zonation. Within the Zn-Pb deposits, framboidal pyrite is the earliest pyrite generation recognized, and this exclusively has negative δ 34 S values (mean = −16.6 ± 4.1 ‰; n = 55), whereas paragenetically later pyrite and galena possess positive δ 34 S values (mean = 29.1 ± 7.5 and 22.4 ± 3.0 ‰, n = 13 and 13, respectively). Previous studies found that sphalerite and galena mineral separates have exclusively positive δ 34S values (mean = 16.8 ± 3.3 and 12.7 ± 2.8 ‰, respectively; Goodfellow and Jonasson 1986). These distinct sulfur isotope values are interpreted to reflect varying contributions of bacterially reduced seawater sulfate (negative; framboidal pyrite) and thermochemically reduced seawater sulfate and/or hydrothermal sulfate (positive; galena, sphalerite, later forms of pyrite). Textural evidence indicates that framboidal pyrite predates galena and sphalerite deposition. Collectively, the in situ and bulk sulfur isotope data are much more complex than δ 34 S values permitted by prevailing genetic models that invoke only biogenically reduced sulfur and coeval deposition of galena, sphalerite, and framboidal pyrite within a euxinic water column, and we present several lines of evidence that argue against this model. Indeed, the new data indicate that much of the base metal sulfide mineralization was emplaced below the sedimentwater interface within sulfidic muds under reducing conditions during early diagenesis. Furthermore, thermochemical sulfate reduction provided most of the reduced sulfur within the Zn-Pb deposits.

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Section: Discussioncontrasting

confidence: 50%

mentioning

confidence: 88%

Section: Sediment-hosted Zn-pb Depositsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The world-class Howard’s Pass SEDEX Zn-Pb district, Selwyn Basin, Yukon. Part II: the roles of thermochemical and bacterial sulfate reduction in metal fixation

et al. 2016

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“…As a result, younger deposits may be limited to areas and episodes of basin-scale anoxia (Goodfellow and Jonasson, 1984;Turner, 1992), or they may have required an oxygen-shielding cap, either through barite deposition or mineralization below the sediment-water interface. The drop-off in abundance of Proterozoic deposits following the peak at 1800-1600 Ga is more diffi cult to explain.…”

Section: Comparisons With Younger Depositsmentioning

confidence: 99%

Proterozoic sedimentary exhalative (SEDEX) deposits and links to evolving global ocean chemistry

Lyons¹,

Gellatly²,

McGoldrick³

et al. 2006

Evolution of Early Earth's Atmosphere, Hydrosphere, and Biosphere - Constraints From Ore Deposits

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Sedimentary exhalative (SEDEX) Zn-Pb-sulfi de mineralization fi rst occurred on a large scale during the late Paleoproterozoic. Metal sulfi des in most Proterozoic deposits have yielded broad ranges of predominantly positive δ 34 S values traditionally attributed to bacterial sulfate reduction. Heavy isotopic signatures are often ascribed to fractionation within closed or partly closed local reservoirs isolated from the global ocean by rifting before, during, and after the formation of Rodinia. Although such conditions likely played a central role, we argue here that the fi rst appearance of signifi cant SEDEX mineralization during the Proterozoic and the isotopic properties of those deposits are also strongly coupled to temporal evolution of the amount of sulfate in seawater.The ubiquity of 34 S-enriched sulfi de in ore bodies and shales and the widespread stratigraphic patterns of rapid δ 34 S variability expressed in both sulfate and sulfi de data are among the principal evidence for global seawater sulfate that was increasing during the Proterozoic but remained substantially lower than today. Because sulfate is produced mostly through weathering of the continents in the presence of oxygen, low Proterozoic concentrations imply that levels of atmospheric oxygen fell between the abundances of the Phanerozoic and the defi ciencies of the Archean, which are also indicated by the Precambrian sulfur isotope record. Given the limited availability of atmospheric oxygen, deep-water anoxia may have persisted well into the Proterozoic in the presence of a growing sulfate reservoir, which promoted prevalent euxinia. Collectively, these observations suggest that the mid-Proterozoic maximum in SEDEX mineralization and the absence of Archean deposits refl ect a critical threshold in the accumulation of oceanic sulfate and thus sulfi de within anoxic bottom waters and pore fl uids-conditions that favored both the production and preservation of sulfi de mineralization at or just below the seafl oor. Consistent with these evolving global conditions, the appearance of voluminous SEDEX mineralization ca. 1800 Ma coincides generally with the disappearance of banded iron formations-marking the transition from an early iron-dominated ocean to one more strongly infl uenced by sulfi de availability. 170 T.W. Lyons et al.

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Sedimentary Records of Present and Past Marine Sulfur Cycling

Strauss

2022

Systems Biogeochemistry of Major Marine Biomes

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Ocean stagnation and ventilation defined by δ34S secular trends in pyrite and barite, Selwyn Basin, Yukon

Cited by 99 publications

References 0 publications

The world-class Howard’s Pass SEDEX Zn-Pb district, Selwyn Basin, Yukon. Part II: the roles of thermochemical and bacterial sulfate reduction in metal fixation

The world-class Howard’s Pass SEDEX Zn-Pb district, Selwyn Basin, Yukon. Part II: the roles of thermochemical and bacterial sulfate reduction in metal fixation

Proterozoic sedimentary exhalative (SEDEX) deposits and links to evolving global ocean chemistry

Sedimentary Records of Present and Past Marine Sulfur Cycling

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