Selenium isotopes trace anoxic and ferruginous seawater conditions in the Early Cambrian

Wen, Hao; Carignan, Jean; Chu, Xuelei; Fan, Haifeng; Cloquet, Christophe; Huang, Jing; Zhang, Yuxu; Chang, Huajin

doi:10.1016/j.chemgeo.2014.10.022

Cited by 43 publications

(32 citation statements)

References 53 publications

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“…Such ferruginous conditions can be classified as suboxic if sulfate was stable in the water column (which is unknown) and may thus not have been conducive for rapid quantitative Se reduction, especially if Se input was high. Importantly, both Wen et al (2014) and Mitchell et al (2012) found relatively more negative δ 82/78 Se values in sediments with molar Se/TOC ratios greater than~10 −5 , i.e. when the Se/TOC ratio exceeded that of marine biomass (2 · 10 −6 to 6 · 10 −6 , Mitchell et al, 2012).…”

Section: Introductionmentioning

confidence: 94%

“…In other words, negative values should reflect a high Se oxyanion supply relative to the demand. Wen et al (2014) recently observed negative δ 82/78 Se values down to −3.3‰ in very Serich Cambrian sediments (up to 121 ppm Se) that were deposited under an Fe 2+ -dominated water column. Such ferruginous conditions can be classified as suboxic if sulfate was stable in the water column (which is unknown) and may thus not have been conducive for rapid quantitative Se reduction, especially if Se input was high.…”

Section: Introductionmentioning

confidence: 98%

“…Selenium isotopic ratios represent a newly emerging biogeochemical proxy (e.g. Mitchell et al, 2012;Wen et al, 2014;Stüeken et al, 2015b) that may help constrain our understanding of changes in ocean redox state and productivity associated with the latest-Permian mass extinction. The processes that control the partitioning of Se isotopes in marine environments are not yet fully understood, but existing information reviewed below and elsewhere (Stüeken et al, 2015b) allows us to construct hypotheses that we seek to test in this study.…”

Section: Introductionmentioning

confidence: 99%

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Selenium isotope ratios, redox changes and biological productivity across the end-Permian mass extinction

et al. 2015

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The causes of the greatest mass extinction in Earth's history, in the latest Permian, remain actively debated. Here we use Se isotopes and abundances in marine sediments from an outer-shelf environment to test one of the most common hypotheses for the collapse of the biosphere, i.e. widespread euxinia in the open ocean. Our data show a small positive excursion in δ 82/78 Se prior to the extinction, consistent with local euxinia. However, this is followed by a significant negative excursion with a minimum of −1.8‰ (relative to NIST SRM 3149), immediately preceding the principal extinction horizon. A net fractionation of this magnitude likely resulted from partial reduction of Se oxyanions dissolved in the water column. Due to their low abundance, Se oxyanions are rapidly scavenged in anoxic basins or regions of high biological productivity with little net isotopic fractionation. We therefore interpret the uniquely negative fractionations in this section as an indicator for relatively oxygenated conditions in this marine basin at the time when biological productivity declined. The offset between the peak excursion and the major extinction horizon possibly reflects a slow-down in ocean circulation leading to nutrient limitation, which may thus have prohibited a rapid recovery of the local biosphere in the early Triassic. Although we are unable to extrapolate to the global ocean due to the short residence time of Se in seawater, our data are consistent with the newly emerging view that euxinia developed along ocean margins and in oxygen minimum zones before the extinction, but was probably replaced by (sub-)oxic conditions during the~1 kyr peak productivity decline and was thus not solely responsible for the extinction event.

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Selenium isotope ratios, redox changes and biological productivity across the end-Permian mass extinction

et al. 2015

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“…Analyses of non-marine sediments or a greater variety of marine facies may help resolve these questions. (Johnson and Bullen 2004b;Rouxel et al 2004;Mitchell et al 2012;Layton-Matthews et al 2013;Wen et al 2014;Pogge von Strandmann et al 2015;Stüeken et al 2015d): With the oxygenation of the deep ocean in the Neoproterozoic or early Paleozoic (Lyons et al 2014), selenium oxyanions probably became more stable, and something like a modern selenium cycle (Fig. 2) was established.…”

Section: Selenium Isotopes In Deep Timementioning

confidence: 99%

Selenium Isotopes as a Biogeochemical Proxy in Deep Time

Stüeken

2017

Reviews in Mineralogy and Geochemistry

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“…The authors showed that Se isotopic fractionation may be induced by microbial or abiotic reduction of Se(VI) and/or Se(IV) to less oxidized Se soil pools. Se isotope ratios bear the potential to show historic redox changes in the ancient oceans through assessment of the Se isotopic signatures recorded in ancient sedimentary rocks [136]. Further, studies on mass independent fractionation of Se in accordance with mass independent fractionation of S isotopes has gained interest during the last years [137].…”

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confidence: 99%

Application of non-traditional stable isotopes in analytical ecogeochemistry assessed by MC ICP-MS - A critical review

Irrgeher

Prohaska

2015

Anal Bioanal Chem

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Analytical ecogeochemistry is an evolving scientific field dedicated to the development of analytical methods and tools and their application to ecological questions. Traditional stable isotopic systems have been widely explored and have undergone continuous development during the last century.The variations of the isotopic composition of light elements (H, O, N, C and S) have provided the foundation of stable isotope analysis followed by the analysis of traditional geochemical isotope tracers (e.g. Pb, Sr, Nd, Hf). Questions in a considerable diversity of scientific fields have been addressed, many of which can be assigned to the field of ecogeochemistry. Over the past fifteen years, other stable isotopes (e.g. Li, Zn, Cu, Cl) have emerged gradually as novel tools for the investigation of scientific topics that arise in ecosystem research and have enabled novel discoveries and explorations. These systems are often referred to as non-traditional isotopes.The small isotopic differences of interest that are increasingly being addressed for a growing number of isotopic systems represent a challenge to the analytical scientist and push the limits of today's instruments constantly. This underlines the importance of a metrologically sound concept of analytical protocols and procedures and a solid foundation of data processing strategies and uncertainty considerations before these small isotopic variations can be interpreted in the context of applied ecosystem research. This review focuses on the development of isotope research in ecogeochemistry, the requirements for successful detection of small isotopic shifts as well as highlights the most recent and innovative applications in the field. Keywordsanalytical ecogeochemistry, non-traditional stable isotopes, isotope tracers, MC ICP-MS, chemical metrology 2

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Selenium isotopes trace anoxic and ferruginous seawater conditions in the Early Cambrian

Cited by 43 publications

References 53 publications

Selenium isotope ratios, redox changes and biological productivity across the end-Permian mass extinction

Selenium isotope ratios, redox changes and biological productivity across the end-Permian mass extinction

Selenium Isotopes as a Biogeochemical Proxy in Deep Time

Application of non-traditional stable isotopes in analytical ecogeochemistry assessed by MC ICP-MS - A critical review

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