The reactivity of sedimentary iron minerals toward sulfide

Canfield, Donald E.; Raiswell, R.; Bottrell, Simon H.

doi:10.2475/ajs.292.9.659

Cited by 703 publications

(462 citation statements)

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“…Even at modern rates of sulfate reduction, such as measured rates of 0.1 mmol cm À 3 per year (ref. 45), this yields 828 years to generate enough HS -for pyritization of moderately sized Conotubus tubes. The decaying organism is a BSR hotspot, which should pull in both SO 4 2-and Fe 2 þ from the surrounding microenvironment (as opposed to assumed steady-state equilibrium 31 ), thus these cited bulk-sediment rates may overestimate the pyritization time.…”

Section: Discussionmentioning

confidence: 99%

A unifying model for Neoproterozoic–Palaeozoic exceptional fossil preservation through pyritization and carbonaceous compression

et al. 2014

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Section: Discussionmentioning

confidence: 99%

A unifying model for Neoproterozoic–Palaeozoic exceptional fossil preservation through pyritization and carbonaceous compression

et al. 2014

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“…The proxy gives a measure of highly reactive Fe to total Fe (Fe HR /Fe T ). Fe HR refers to Fe minerals that are considered highly reactive towards biological and abiological reduction under anoxic conditions (Canfield et al, 1992;Poulton et al, 2004b), and includes carbonate-associated Fe (Fe carb ; e.g., ankerite and siderite), ferric (oxyhydr)oxides (Fe ox ; e.g., goethite and hematite), magnetite Fe (Fe mag ) and Fe sulfide minerals (Fe py ; e.g., makinawite and pyrite) (Poulton and Canfield, 2005). Sediments may be enriched in Fe HR under anoxic marine conditions due to either the export of remobilized Fe (aq) from the oxic shelf (Anderson and Raiswell, 2004;Severmann et al, 2008) or under more widespread anoxia, due to upwelling of deep water Fe(II) (Poulton and Canfield, 2011).…”

Section: Fe-speciationmentioning

confidence: 99%

Dynamic redox conditions control late Ediacaran metazoan ecosystems in the Nama Group, Namibia

Wood

Poulton

Prave

et al. 2015

Precambrian Research

166

194

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A c c e p t e d M a n u s c r i p t 3 ABSTRACTThe first appearance of skeletal metazoans in the late Ediacaran (~550 million years ago; Ma) has been linked to the widespread development of oxygenated oceanic conditions, but a precise spatial and temporal reconstruction of their evolution has not been resolved. Here we consider the evolution of ocean chemistry from ~550 to ~541 Ma across shelf-to-basin transects in the Zaris and Witputs Sub-Basins of the Nama Group, Namibia. New carbon isotope data capture the final stages of the Shuram/Wonoka deep negative C-isotope excursion, and these are complemented with a reconstruction of water column redox dynamics utilizing Fe-S-C systematics and the distribution of skeletal and soft-bodied metazoans. Combined, these inter-basinal datasets provide insight into the potential role of ocean redox chemistry during this pivotal interval of major biological innovation.The strongly negative  13 C values in the lower parts of the sections reflect both a secular, global change in the C-isotopic composition of Ediacaran seawater, as well as the influence of 'local' basinal effects as shown by the most negative  13 C values occurring in the transition from distal to proximal ramp settings. Critical, though, is that the transition to positive  13 C values postdates the appearance of calcified metazoans, indicating that the onset of biomineralization did not occur under post-excursion conditions. Significantly, we find that anoxic and ferruginous deeper water column conditions were prevalent during and after the transition to positive  13 C that marks the end of the Shuram/Wonoka excursion. Thus, if the C isotope trend reflects the transition to global-scale oxygenation in the aftermath of the oxidation of a large-scale, isotopically light organic carbon pool, it was not sufficient to fully oxygenate the deep ocean. Page 4 of 74A c c e p t e d M a n u s c r i p t 4 Both sub-basins reveal highly dynamic redox structures, where shallow, inner ramp settings experienced transient oxygenation. Anoxic conditions were caused either by episodic upwelling of deeper anoxic waters or higher rates of productivity. These settings supported short-lived and monospecific skeletal metazoan communities. By contrast, microbial (thrombolite) reefs, found in deeper inner-and mid-ramp settings, supported more biodiverse communities with complex ecologies and large skeletal metazoans. These long-lived reef communities, as well as Ediacaran soft-bodied biotas, are found particularly within transgressive systems, where oxygenation was persistent. We suggest that a mid-ramp position enabled physical ventilation mechanisms for shallow water column oxygenation to operate during flooding and transgressive sea-level rise. Our data support a prominent role for oxygen, and for stable oxygenated conditions in particular, in controlling both the distribution and ecology of Ediacaran skeletal metazoan communities.Keywords: Oxygenation; Neoproterozoic; Biomineralisation; Metazoans; Ediacaran; Ecosystems Introductio...

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“…It is worth pointing out that the empirical approach is in conflict with the findings of Canfield et al (1992), who deduced half-lives of sedimentary iron minerals with respect to sulphidation. They concluded that the half-life for sheet silicates is 84,000 years, which is within the time frame of the Pleistocene period.…”

Section: Reactive Fe Mineralsmentioning

confidence: 89%

“…This means that the empirical relationship may be useful for Holocene sediments, but might be more questionable for sediments of Middle Pleistocene age and older. Here, the conclusion of Canfield et al (1992) is probably a simplification too. It is also worth mentioning that in the 19th century Van Bemmelen (1863) proposed the concept of a fixed Al 2 O 3 to Fe 2 O 3 ratio in silicates of clay: the Fe 2 O 3 content is about 7% when the Al 2 O 3 content is 15-20% and it is 2.5% at the transition between clay and sand.…”

Section: Reactive Fe Mineralsmentioning

confidence: 96%

The mineralogy of suspended matter, fresh and Cenozoic sediments in the fluvio-deltaic Rhine–Meuse–Scheldt–Ems area, the Netherlands: An overview and review

Griffioen

Klaver

Westerhoff

2016

Netherlands Journal of Geosciences

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Minerals are the building blocks of clastic sediments and play an important role with respect to the physico-chemical properties of the sediment and the lithostratigraphy of sediments. This paper aims to provide an overview of the mineralogy (including solid organic matter) of sediments as well as suspended matter as found in the Netherlands (and some parts of Belgium). The work is based on a review of the scientific literature published over more than 100 years. Cenozoic sediments are addressed together with suspended matter and recent sediments of the surface water systems because they form a geoscientific continuum from material subject to transport via recently settled to aged material. Most attention is paid to heavy minerals, clay minerals, feldspars, Ca carbonates, reactive Fe minerals (oxides, siderite, sulphides, glauconite) and solid organic matter because they represent the dominant minerals and their properties form a main issue in subsurface and water management. When possible and relevant, the amounts, provenance, relationship with grain size distribution, early diagenesis and palaeohydrological evolution are described. Tables with statistical data about the mineral contents and isotopic composition of carbonates and organic matter are presented as overviews. The review on the mineralogy of Dutch fluvial and marine environments is more extensive than that for the other sedimentary environments because the first two have been studied much more intensively than the others and they also form the larger part of the Dutch deposits. The focus is on the natural background mineralogy of Dutch sediments, but this is hard for recent sediments, largely because the massive hydraulic infrastructure present in the Netherlands has probably also affected the mineralogy and geochemistry of sediments deposited in recent centuries. Many findings are summarised, several of which lead to more general insights for the Dutch situation. Ca carbonates in sediments often have several provenances and thus must be considered as mixtures. Dolomite is commonly present in addition to calcite. The importance of biotite as weatherable mica is unclear. Weathering of heavy minerals plays some role but it is unclear in which way it affects the heavy mineral associations. Clays are usually dominated by illite, smectite and their interstratified variant, while kaolinite is usually below 20% and chlorite below 5%. Vermiculite is a minor constituent in fluvial clays and its illitisation presumably happens during early diagenesis in the marine environment. Opaque Fe hydroxides can be present in addition to Fe oxyhydroxide coatings and both will play a role in redox chemistry as reactive Fe minerals. Feldspars in marine sediments must be present but they have not been properly studied. The genesis of rattle stones and carbonate concretions has not been completely elucidated. The fraction of terrigeneous organic matter in estuarine and coastal marine sediments is substantial. The available data and information are spread irregularly over the country and the reviewed information discussed in this paper is derived from relatively small-scale studies dealing with a limited amount of analysed samples. Much information is available from the Scheldt estuaries in the southwestern part of the Netherlands partly due to the severe contamination of the Western Scheldt in recent decades.

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The reactivity of sedimentary iron minerals toward sulfide

Cited by 703 publications

References 0 publications

A unifying model for Neoproterozoic–Palaeozoic exceptional fossil preservation through pyritization and carbonaceous compression

A unifying model for Neoproterozoic–Palaeozoic exceptional fossil preservation through pyritization and carbonaceous compression

Dynamic redox conditions control late Ediacaran metazoan ecosystems in the Nama Group, Namibia

The mineralogy of suspended matter, fresh and Cenozoic sediments in the fluvio-deltaic Rhine–Meuse–Scheldt–Ems area, the Netherlands: An overview and review

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