Oxidative elemental cycling under the low O2 Eoarchean atmosphere

Frei, Robert; Crowe, Sean A.; Bau, Michael; Polat, Ali; Fowle, David A.; Døssing, Lasse Nørbye

doi:10.1038/srep21058

Cited by 80 publications

(41 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similarly, Cr isotopes from the 2.98 Ga Nsuze paleosol, also in the Pongola Supergroup, have been used as evidence for significant oxidative weathering on land, and thus appreciable levels of atmospheric oxygen, even at that time (Crowe et al, 2013). Frei et al (2016) combined U/Th ratios and Cr isotopes to argue for oxidative weathering as far back in time as the 3.8-3.7 Ga Isua Supracrustal Belt, but at very low atmosphere oxygen contents (i.e., <<10 -5 present atmospheric levels, PAL; Fig. 10).…”

Section: Evidence In the Rock Record For The Evolution Of Oxygenic Phmentioning

confidence: 99%

Iron formations: A global record of Neoarchaean to Palaeoproterozoic environmental history

Konhauser

Planavsky

Hardisty

et al. 2017

Earth-Science Reviews

337

257

View full text Add to dashboard Cite

Section: Evidence In the Rock Record For The Evolution Of Oxygenic Phmentioning

confidence: 99%

Iron formations: A global record of Neoarchaean to Palaeoproterozoic environmental history

Konhauser

Planavsky

Hardisty

et al. 2017

Earth-Science Reviews

337

257

View full text Add to dashboard Cite

“…Banded iron formations (BIF) are rocks of alternating layers rich in silica with layers rich in iron oxides (Posth et al, 2008; Walter, 2011; Frei et al, 2016). BIF occur in geological records of several periods of the Archean (4 Ga to 2.5 Ga) and the Proterozoic (2.5 Ga – 0.54 Ga), especially between the Neoarchean (late Archean) and Early Paleoproterozoic – the Siderian – (2.7–2.4 Ga, Pecoits et al, 2015).…”

Section: Evolution Of the Biogeochemical Conditions In Ancient Oceansmentioning

confidence: 99%

Photoferrotrophy: Remains of an Ancient Photosynthesis in Modern Environments

et al. 2017

View full text Add to dashboard Cite

Photoferrotrophy, the process by which inorganic carbon is fixed into organic matter using light as an energy source and reduced iron [Fe(II)] as an electron donor, has been proposed as one of the oldest photoautotrophic metabolisms on Earth. Under the iron-rich (ferruginous) but sulfide poor conditions dominating the Archean ocean, this type of metabolism could have accounted for most of the primary production in the photic zone. Here we review the current knowledge of biogeochemical, microbial and phylogenetic aspects of photoferrotrophy, and evaluate the ecological significance of this process in ancient and modern environments. From the ferruginous conditions that prevailed during most of the Archean, the ancient ocean evolved toward euxinic (anoxic and sulfide rich) conditions and, finally, much after the advent of oxygenic photosynthesis, to a predominantly oxic environment. Under these new conditions photoferrotrophs lost importance as primary producers, and now photoferrotrophy remains as a vestige of a formerly relevant photosynthetic process. Apart from the geological record and other biogeochemical markers, modern environments resembling the redox conditions of these ancient oceans can offer insights into the past significance of photoferrotrophy and help to explain how this metabolism operated as an important source of organic carbon for the early biosphere. Iron-rich meromictic (permanently stratified) lakes can be considered as modern analogs of the ancient Archean ocean, as they present anoxic ferruginous water columns where light can still be available at the chemocline, thus offering suitable niches for photoferrotrophs. A few bacterial strains of purple bacteria as well as of green sulfur bacteria have been shown to possess photoferrotrophic capacities, and hence, could thrive in these modern Archean ocean analogs. Studies addressing the occurrence and the biogeochemical significance of photoferrotrophy in ferruginous environments have been conducted so far in lakes Matano, Pavin, La Cruz, and the Kabuno Bay of Lake Kivu. To date, only in the latter two lakes a biogeochemical role of photoferrotrophs has been confirmed. In this review we critically summarize the current knowledge on iron-driven photosynthesis, as a remains of ancient Earth biogeochemistry.

show abstract

“…2.96 Ga (Crowe et al., ) and has even been used to infer the presence of “reactive oxygen species” as far back as ca. 3.7–3.8 Ga (Frei et al., ).…”

Section: Introductionmentioning

confidence: 99%

Chromium geochemistry of the ca. 1.85 Ga Flin Flon paleosol

2016

View full text Add to dashboard Cite

Fractionation of stable Cr isotopes has been measured in Archaean paleosols and marine sedimentary rocks and interpreted to record the terrestrial oxidation of Cr(III) to Cr(VI), providing possible indirect evidence for the emergence of oxygenic photosynthesis. However, these fractionations occur amidst evidence from other geochemical proxies for a pervasively anoxic atmosphere. This study examined the Cr geochemistry of the ca. 1.85 Ga Flin Flon paleosol, which developed under an atmosphere unambiguously oxidising enough to quantitatively convert Fe(II) to Fe(III) during pedogenesis. The paleosol shows an extreme range in Cr isotope composition of 2.76 ‰ δ Cr. The protolith greenstone (δ Cr: -0.23 ‰), the deepest weathering horizon (δ Cr: -0.15 to -0.23 ‰) and a residual corestone in the upper paleosol (δ Cr: -0.01 ‰) all exhibit Cr isotopic compositions comparable to unaltered igneous rocks. The most significant isotopic fractionation is preserved in the areas influenced by oxidative subaerial weathering (i.e. increase in Fe(III)/Fe(II)) and the greatest loss of mobile elements. The uppermost paleosol horizon is both Cr and Mn depleted and offset to significantly Cr-enriched compositions (δ Cr values between +1.50 and +2.38 ‰), which is not easily modelled with the oxidation of Cr(III) and loss of isotopically heavy Cr(VI). Instead, the currently preferred model for these data invokes the open-system removal of isotopically light aqueous Cr(III) during either pedogenesis or subsequent hydrothermal/metamorphic alteration. The Cr enrichment would then represent the preferential dissolution or complexation of isotopically light aqueous Cr(III) species (enhanced by lower pH conditions and possibly the presence of complexing ligands) and/or the residual signature from preferential adsorption of isotopically heavy Cr(III). Both scenarios would contradict the widely held assumption that only redox reactions of Cr can generate large magnitude isotopic fractionations and, if substantiated, non-redox isotope effects would complicate the conclusive fingerprinting of ancient atmospheric O from Cr isotope data alone.

show abstract

Oxidative elemental cycling under the low O2 Eoarchean atmosphere

Cited by 80 publications

References 48 publications

Iron formations: A global record of Neoarchaean to Palaeoproterozoic environmental history

Iron formations: A global record of Neoarchaean to Palaeoproterozoic environmental history

Photoferrotrophy: Remains of an Ancient Photosynthesis in Modern Environments

Chromium geochemistry of the ca. 1.85 Ga Flin Flon paleosol

Contact Info

Product

Resources

About