This contribution is an updated review on sedimentary pyrite and on its role in well-consolidated research topics, such as the biogeochemical cycles and the studies on sediment-hosted ore deposit studies, as well as new frontiers of research, such as astrobiology. Textural and compositional information preserved in sedimentary pyrite from sediment-hosted ore deposits has …
Anoxic-sulfidic environments are usually associated with the presence of free H 2 S in the sediment pore water (or in the water-column), and the formation of pyrite leads to higher DOP values in ...
Field studies of modern marine sediments have shown that the δ 34 S of pyrite can be influenced by several factors, including diagenetic pyrite formation at the sulfate–methane transition (SMT) and changes in local depositional conditions (e.g., Borowski et al., 2013, Fike et al., 2015, Pasquier et al., 2017, Riedinger et al., 2017).
Sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater over geologic time. The amount of pyrite that may form in a sediment is limited by the rates of supply of decomposable organic matter, dissolved sulfate, and reactive detrital iron minerals.
Sulfur isotope analysis of authigenic pyrite in the Creede Formation documents its precipitation by the reaction between iron in the volcaniclastic sediments and H2S formed through bacteriogenic reduction of sulfate added to the lake during and immediately following repeated volcanic eruptions during sedimentation. Pyrite veinlets in the underlying Snowshoe Mountain Tuff were formed by the ...
Pyrite formation in the water column and sediments of a meromictic lake. We compared concentrations of organic carbon, partitioning of iron and sulfur, stable isotopic ratios of major sulfur species, and pyrite morphologies in the water column and sediments of oxic and euxinic portions of a sulfate-rich, meromictic lake (Green Lake near ...
monosulfides (generic for mackinawite and/or greigite), are necessary precursors for pyrite formation in sediments. Thus, the normal iron sulfide paragenesis in sediments is presumed to proceed from mackinawite over greigite to pyrite (e.g. Wilkin and Barnes, 1996; Benning et al., 2000).
These trends, which also occrr in the sediments of the soutl basin, suggest tlat the formation of pyrite in tle surface sediments has been inhibited since copp€r sulfate treafinent. This inhibition arises from the reduced deposition oforganic matter or copper ion toxicity to sulfate-reducing bacterira (or both).
the sediment. The formation mechanism of the framboids is reviewed, but many questions still exist. INTRODUCTION As Regnéll has observed (1960, p. 305), "formation of iron sulphide in deep-sea sediments seems not to be an ordinary process," noting that "abundant pyrite has rarely been found in deep-sea sediments" (p. 313). Qual-
possible pathways of both pyrite and organic sulfur formation in marine sediments. Sulfur isotope data indicate that pyrite in the Cariaco Basin is formed both in the water column (syngenetically) and in the sediments (diagenetically) and that pyrite accumula-tion has varied significantly over the past 12 14Cky.
Pyrite formation and the measurement of sulfate reduction in salt marsh sediments l Robert W. Howarth and Susan Merkel The Ecosystems Center, Marine Biological Laboratory, Woods Hole, Massachusetts 02543 Abstract A new method was used to study the formation of pyrite plus elemental sulfur during 35S0,2-
These sediments contain a small lithogenous fraction and a large biogenous, organic C-rich fraction, which decays by sulfate reduction in an iron-rich water column to form pyrite-rich sediment. Other anaerobic/euxinic samples from the Black Sea, Orca Basin, and Kau Bay contain lower concentrations of biogenous sediment and are not therefore ...
The formation of pyrite is strongly exergonic in anoxic sediments. Therefore, the reductive dissolution is expectedly an energy-requiring process.
Sulfur isotope values of pyrite (δ 34 S pyrite) capture isotopic signatures of ambient sulfide at the location of pyrite formation (e.g., at different locations in the sediment column or in the water column versus the sediment; Lyons, 1997), and therefore, recorded values are not always representative of an entire system where they form.
sedimentary pyrite opens up the prospect to greatly expand our knowledge of microbial life in very old sediments, as well as allowing us much more detailed analysis of microbial life throughout Earth history. Sedimentary pyrite grains may also represent a good prospect to find traces of past life on Mars.
adshelp[at]cfa.harvard.edu The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative Agreement NNX16AC86A
Sedimentary pyrite can form in the water column or in sediments. Pyrite formation requires active iron and sulfide present, but because sulfide is …
Abstract The early diagenetic characteristics of pyrite formation processes in a Miocene freshwater sequence of mixed sediments (coal fragments in clays, sandstones or shales) alternating with continuous brown coal layers was investigated. Based on abundant minerals, the following main sedimentary environments were distinguished: the illite-montmorillonitic (I-M), calcitic (Ct) and coal ...
Pyrite formation in the water column and sediments of a meromictic lake. We compared concentrations of organic carbon, partitioning of iron and sulfur, stable isotopic ratios of major sulfur species, and pyrite morphologies in the water column and sediments of oxic and euxinic portions of a sulfate-rich, meromictic lake (Green Lake near ...
Examples of periodic pyrite bands have been previously reported in anoxic sediment systems, such as sapropels from the Eastern Mediterranean. In this contribution, we present a model of Liesegang pyrite band formation in anoxic marine sediments. The model is based on early diagenetic reactive-transport processes and incorporates nucleation and ...
An occurrence of pyrite oxidation in the anoxic regions of pyritic sediments indicates that pyrite formation and accumulation in the reducing environments are not dominant processes. Rather, pyrite is being oxidized as they are formed. Consequently, the process of bacterial sulfate reduction for pyrite formation in the anoxic zones of pyritic ...
The iron isotope composition of sedimentary pyrite has been proposed as a potential proxy to trace microbial metabolism and the redox evolution of the oceans. We demonstrate that Fe isotope fractionation accompanies abiotic pyrite formation in the absence of …
Based on pyrite textures, S-isotopic compositions of water-column and sediment sulfides, and settling rate calculations, about 70% of the pyrite burial flux to the Pettaquamscutt sediments is accounted for by framboids forming at the oxic-anoxic interface and settling to the sediment-water interface.
In normal marine sediments the correlation C org -S pyrite is positive and linear with a zero sulfur intercept and a C org /S pyrite ratio of ~2.8 (Berner, 1982;Morse and Berner, 1995).
As the major reservoir of reduced S in marine sediments, stable authigenic pyrite is formed at the redox interface of sediments, and the pyrite formation is generally restricted by the supply of decomposable organic matter, dissolved sulfate and …
Pyrite synthesis was examined in the laboratory, and the chemical, crystallographic and textural results were compared with naturally occurring pyrite in marine sediment. The path of pyrite formation begins with reaction of hydrogen sulfide and dissolved iron. The first product is either amorphous iron sulfide or mackinawite with composition ...
Early diagenesis of iron and sulfur in Bornholm Basin sediments: the role of near-surface pyrite formation. Geochimica et Cosmochimica Acta 284, 43−60 (2020). 50.
In this study, pyrite formation in relation to environmental conditions was investigated in sediment records from the northern Arabian Sea. Considering the low bottom-water oxygen concentrations in the oxygen minimum zone (OMZ) and the high rates of primary productivity on the Oman and Pakistan Margins, sedimentary pyritic S concentrations are unexpectedly low (on average …
Pyrite seldom forms in fresh-water environments. The formation of pyrite crystals depends mainly on the iron content of the sediment. The process of pyrite formation in sediments results from the action of bacteria, which reduce sulphate ions (dissolved in the pore water) to sulphide. If there is iron present, iron sulphide crystals begin to grow.
Sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater over geologic time. The amount of pyrite that may form in a sediment is limited by the rates of supply of decomposable organic matter, dissolved sulfate, and reactive detrital iron minerals.