The 13C12C ratios of siderite and organic matter of a modern metalliferous hydrothermal sediment and their implications for banded iron formations

1989 ◽  
Vol 77 (1) ◽  
pp. 41-45 ◽  
Author(s):  
Nils G. Holm
Keyword(s):  
Organic Matter ◽  
Banded Iron Formations ◽  
Hydrothermal Sediment ◽  
Iron Formations

scholarly journals Minimal biomass deposition in banded iron formations inferred from organic matter and clay relationships

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Matthew S. Dodd ◽  
Dominic Papineau ◽  
Franco Pirajno ◽  
Yusheng Wan ◽  
Juha A. Karhu
Keyword(s):  
Organic Matter ◽  
Primary Productivity ◽  
Iron Reduction ◽  
Biogeochemical Cycle ◽  
Complete Oxidation ◽  
Iron Cycling ◽  
Banded Iron Formations ◽  
Iron Formations

Abstract The cycling of iron and organic matter (OM) is thought to have been a major biogeochemical cycle in the early ferruginous oceans which contributed to the deposition of banded iron formations (BIF). However, BIF are deficient in OM, which is postulated to be the result of near-complete oxidation of OM during iron reduction. We test this idea by documenting the prevalence of OM in clays within BIF and clays in shales associated with BIF. We find in shales >80% of OM occurs in clays, but <1% occurs in clays within BIF. Instead, in BIF OM occurs with 13C-depleted carbonate and apatite, implying OM oxidation occurred. Conversely, BIF which possess primary clays would be expected to preserve OM in clays, yet this is not seen. This implies OM deposition in silicate-bearing BIF would have been minimal, this consequently stifled iron-cycling and primary productivity through the retention of nutrients in the sediments.

scholarly journals Iron and Carbon Isotope Constraints on the Formation Pathway of Iron-Rich Carbonates within the Dagushan Iron Formation, North China Craton

Minerals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 94
Author(s):  
Xiaoxue Tong ◽  
Kaarel Mänd ◽  
Yuhao Li ◽  
Lianchang Zhang ◽  
Zidong Peng ◽  
...  
Keyword(s):  
Iron Reduction ◽  
Isotope Composition ◽  
Iron Formation ◽  
Banded Iron Formations ◽  
Organic C ◽  
Formation Pathway ◽  
Wide Range ◽  
Dissimilatory Iron Reduction ◽  
O Isotope ◽  
Iron Formations

Banded iron formations (BIFs) are enigmatic chemical sedimentary rocks that chronicle the geochemical and microbial cycling of iron and carbon in the Precambrian. However, the formation pathways of Fe carbonate, namely siderite, remain disputed. Here, we provide photomicrographs, Fe, C and O isotope of siderite, and organic C isotope of the whole rock from the ~2.52 Ga Dagushan BIF in the Anshan area, China, to discuss the origin of siderite. There are small magnetite grains that occur as inclusions within siderite, suggesting a diagenetic origin of the siderite. Moreover, the siderites have a wide range of iron isotope compositions (δ56FeSd) from −0.180‰ to +0.463‰, and a relatively negative C isotope composition (δ13CSd = −6.20‰ to −1.57‰). These results are compatible with the reduction of an Fe(III)-oxyhydroxide precursor to dissolved Fe(II) through microbial dissimilatory iron reduction (DIR) during early diagenesis. Partial reduction of the precursor and possible mixing with seawater Fe(II) could explain the presence of siderite with negative δ56Fe, while sustained reaction of residual Fe(III)-oxyhydroxide could have produced siderite with positive δ56Fe values. Bicarbonate derived from both DIR and seawater may have provided a C source for siderite formation. Our results suggest that microbial respiration played an important role in the formation of siderite in the late Archean Dagushan BIF.

scholarly journals Spectral characteristics of banded iron formations in Singhbhum craton, eastern India: Implications for hematite deposits on Mars

2016 ◽  
Vol 7 (6) ◽  
pp. 927-936 ◽  
Author(s):  
Mahima Singh ◽  
Jayant Singhal ◽  
K. Arun Prasad ◽  
V.J. Rajesh ◽  
Dwijesh Ray ◽  
...  
Keyword(s):  
Spectral Characteristics ◽  
Eastern India ◽  
Banded Iron Formations ◽  
Singhbhum Craton ◽  
Iron Formations

scholarly journals Microbial processes during deposition and diagenesis of Banded Iron Formations

PalZ ◽  
2021 ◽  
Author(s):  
Carolin L. Dreher ◽  
Manuel Schad ◽  
Leslie J. Robbins ◽  
Kurt O. Konhauser ◽  
Andreas Kappler ◽  
...  
Keyword(s):  
Microbial Reduction ◽  
Iron Cycling ◽  
Banded Iron Formations ◽  
Geochemical Composition ◽  
High Pressure And Temperature ◽  
Microbial Life ◽  
Reducing Bacteria ◽  
Iron Formations ◽  
Chemical Sediments

AbstractBanded Iron Formations (BIFs) are marine chemical sediments consisting of alternating iron (Fe)-rich and silica (Si)-rich bands which were deposited throughout much of the Precambrian era. BIFs represent important proxies for the geochemical composition of Precambrian seawater and provide evidence for early microbial life. Iron present in BIFs was likely precipitated in the form of Fe3+ (Fe(III)) minerals, such as ferrihydrite (Fe(OH)3), either through the metabolic activity of anoxygenic photoautotrophic Fe2+ (Fe(II))-oxidizing bacteria (photoferrotrophs), by microaerophilic bacteria, or by the oxidation of dissolved Fe(II) by O2 produced by early cyanobacteria. However, in addition to oxidized Fe-bearing minerals such as hematite (FeIII2O3), (partially) reduced minerals such as magnetite (FeIIFeIII2O4) and siderite (FeIICO3) are found in BIFs as well. The presence of reduced Fe in BIFs has been suggested to reflect the reduction of primary Fe(III) minerals by dissimilatory Fe(III)-reducing bacteria, or by metamorphic (high pressure and temperature) reactions occurring in presence of buried organic matter. Here, we present the current understanding of the role of Fe-metabolizing bacteria in the deposition of BIFs, as well as competing hypotheses that favor an abiotic model for BIF deposition. We also discuss the potential abiotic and microbial reduction of Fe(III) in BIFs after deposition. Further, we review the availability of essential nutrients (e.g. P and Ni) and their implications on early Earth biogeochemistry. Overall, the combined results of various ancient seawater analogue experiments aimed at assessing microbial iron cycling pathways, coupled with the analysis of the BIF rock record, point towards a strong biotic influence during BIF genesis.

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