A critical look at iron paleoredox proxies: New insights from modern euxinic marine basins

Lyons, Timothy W.; Severmann, Silke

doi:10.1016/j.gca.2006.08.021

Cited by 513 publications

(356 citation statements)

References 103 publications

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“…This surplus of Fe could have been causally related to high diatom production and sedimentary Si enrichment, as suggested by Stickley et al [2008]. We suggest that most pyrite-bound excess Fe was provided through a "Fe shuttle" mechanism like it is active in the modern Black Sea [Canfield et al, 1996;Wijsman et al, 2001;Anderson and Raiswell, 2004;Lyons and Severmann, 2006]. This mechanism implies a stratified Arctic Ocean with a suboxic water layer separating oxic surface from euxinic deeper waters.…”

Section: Lower To Middle Eocene Geochemical Unit Dmentioning

confidence: 63%

Paleoenvironmental implications of Cenozoic sediments from the central Arctic Ocean (IODP Expedition 302) using inorganic geochemistry

2010

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[1] Integrated Ocean Drilling Program (IODP) Expedition 302 (Arctic Coring Expedition, ACEX) recovered a unique sediment record from the central Arctic Ocean, revealing that this region underwent major environmental fluctuations since the Late Cretaceous. Major and trace element composition of 1,300 samples were determined using X-ray fluorescence (XRF). The results show significant compositional variability of the sediments with depth that can be attributed to changes in (a) provenance and pathways of detrital material, (b) paleoenvironmental conditions and depositional processes, and (c) diagenetic overprint of the primary record. In addition to existing lithological units, we introduce new geochemical units for a more process-related approach interpreting the ACEX record. In detail, via the geochemical signature of Siberian flood basalts we are able to reconstruct the discontinuous rifting and deepening of the central Lomonosov Ridge during the Paleogene, accompanied by changing current regimes and the onset of sea ice. Eocene biosiliceous sedimentation took place in a relatively shallow setting under predominantly anoxic bottom water conditions, causing a positive anoxia-productivity feedback, although water column stratification was repeatedly interrupted by ventilation events. Anoxic to sulfidic conditions were even more extreme after biosilica production ceased, and significant amounts of pyrite were deposited on the Lomonosov Ridge. Especially in organic matter-rich Paleogene deposits, diagenetic processes obscured the paleoenvironmental signals. Fundamental environmental changes occurred in the Middle Eocene, but geochemical and micropaleontological proxies point not to the identical sediment depth. After approximately 26 Ma of non-deposition or erosion, the Middle Miocene record shows the transition to dominantly oxic bottom water conditions, although suboxic diagenesis seemingly affected these deposits.

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Section: Lower To Middle Eocene Geochemical Unit Dmentioning

confidence: 63%

Paleoenvironmental implications of Cenozoic sediments from the central Arctic Ocean (IODP Expedition 302) using inorganic geochemistry

2010

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“…In such euxinic settings, pyrite formation becomes iron-limited and pyrite burial becomes sensitive to the supply of Fe (HR) to the ocean (38). Mechanisms for Fe (HR) supply are hydrothermal input, windblown dust, riverine input, and diagenetic iron cycling on the shelf (39,40). Although the iron flux from the continent is potentially large, 70 18 O phos (‰-VSMOW) 18 O CAS (‰-VSMOW) Fig.…”

Section: Resultsmentioning

confidence: 99%

Flourishing ocean drives the end-Permian marine mass extinction

Schobben

Stebbins

Ghaderi

et al. 2015

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

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The end-Permian mass extinction, the most severe biotic crisis in the Phanerozoic, was accompanied by climate change and expansion of oceanic anoxic zones. The partitioning of sulfur among different exogenic reservoirs by biological and physical processes was of importance for this biodiversity crisis, but the exact role of bioessential sulfur in the mass extinction is still unclear. Here we show that globally increased production of organic matter affected the seawater sulfate sulfur and oxygen isotope signature that has been recorded in carbonate rock spanning the Permian−Triassic boundary. A bifurcating temporal trend is observed for the strata spanning the marine mass extinction with carbonate-associated sulfate sulfur and oxygen isotope excursions toward decreased and increased values, respectively. By coupling these results to a box model, we show that increased marine productivity and successive enhanced microbial sulfate reduction is the most likely scenario to explain these temporal trends. The new data demonstrate that worldwide expansion of euxinic and anoxic zones are symptoms of increased biological carbon recycling in the marine realm initiated by global warming. The spatial distribution of sulfidic water column conditions in shallow seafloor environments is dictated by the severity and geographic patterns of nutrient fluxes and serves as an adequate model to explain the scale of the marine biodiversity crisis. Our results provide evidence that the major biodiversity crises in Earth's history do not necessarily implicate an ocean stripped of (most) life but rather the demise of certain eukaryotic organisms, leading to a decline in species richness.sulfur cycle | end-Permian mass extinction | primary productivity

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“…All datasets compiled from previous studies (Tables S3 and S4 in the supplementary database) were filtered first to identify marine, fine-grained siliciclastic sediments based on literature information and petrographic examination. ORM are defined by having a total organic carbon content of >0.4 wt% (Lyons and Severmann, 2006;Partin et al, 2013;Reinhard et al, 2013a), which also helps to avoid spuriously high Re/TOC ratios in our compilation. We further applied the geochemical filter of Fe T /Al >0.5, which typically delineates sediments deposited under anoxic conditions (e.g., Lyons and Severmann, 2006;Poulton et al, 2010;Planavsky et al, 2011).…”

Section: Methodsmentioning

confidence: 99%

“…ORM are defined by having a total organic carbon content of >0.4 wt% (Lyons and Severmann, 2006;Partin et al, 2013;Reinhard et al, 2013a), which also helps to avoid spuriously high Re/TOC ratios in our compilation. We further applied the geochemical filter of Fe T /Al >0.5, which typically delineates sediments deposited under anoxic conditions (e.g., Lyons and Severmann, 2006;Poulton et al, 2010;Planavsky et al, 2011). Where the above information is not available, efforts were made to determine local redox conditions using other geochemical proxies (e.g., Mo enrichments).…”

Section: Methodsmentioning

confidence: 99%

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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A critical look at iron paleoredox proxies: New insights from modern euxinic marine basins

Cited by 513 publications

References 103 publications

Paleoenvironmental implications of Cenozoic sediments from the central Arctic Ocean (IODP Expedition 302) using inorganic geochemistry

Paleoenvironmental implications of Cenozoic sediments from the central Arctic Ocean (IODP Expedition 302) using inorganic geochemistry

Flourishing ocean drives the end-Permian marine mass extinction

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

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