A productivity collapse to end Earth’s Great Oxidation

Hodgskiss, Malcolm S.W.; Crockford, Peter W.; Peng, Yongbo; Wing, Boswell A.; Horner, Tristan J.

doi:10.1073/pnas.1900325116

Cited by 97 publications

(75 citation statements)

References 55 publications

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“…It implies a huge increase in organic carbon burial rate 5 , recently proposed to be unrealistic 6 , although theoretically possible, and for which direct evidence is still lacking 17 . It also implies an important oxygenation increase, and while recent works seem to indicate that oxygen concentration was indeed appreciably higher during the Paleoproterozoic 18,19 , the temporal coincidence between oxygenation and the LJE is not clearly established yet [20][21][22] . Moreover, significant spatial variations in the CIEs of the LJE were highlighted, not only in amplitude but also in timing and duration 7 .…”

mentioning

confidence: 96%

Carbon isotope evidence for large methane emissions to the Proterozoic atmosphere

Cadeau

Jézéquel

Leboulanger

et al. 2020

Sci Rep

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The Proterozoic Era records two periods of abundant positive carbon isotope excursions (CIEs), conventionally interpreted as resulting from increased organic carbon burial and leading to Earth’s surface oxygenation. As strong spatial variations in the amplitude and duration of these excursions are uncovered, this interpretation is challenged. Here, by studying the carbon cycle in the Dziani Dzaha Lake, we propose that they could be due to regionally variable methane emissions to the atmosphere. This lake presents carbon isotope signatures deviated by ~ + 12‰ compared to the modern ocean and shares a unique combination of analogies with putative Proterozoic lakes, interior seas or restricted epireic seas. A simple box model of its Carbon cycle demonstrates that its current isotopic signatures are due to high primary productivity, efficiently mineralized by methanogenesis, and to subsequent methane emissions to the atmosphere. By analogy, these results might allow the reinterpretation of some positive CIEs as at least partly due to regionally large methane emissions. This supports the view that methane may have been a major greenhouse gas during the Proterozoic Era, keeping the Earth from major glaciations, especially during periods of positive CIEs, when increased organic carbon burial would have drowned down atmospheric CO2.

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mentioning

confidence: 96%

Carbon isotope evidence for large methane emissions to the Proterozoic atmosphere

Cadeau

Jézéquel

Leboulanger

et al. 2020

Sci Rep

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“…1) contributes a significant proportion of pyrite oxidation-derived sulfate, and 2) primary ∆ 17 O signals are not overprinted or diluted in the environment prior to being preserved in the rock record. Tropospheric O2 17 O compositions in the geologic past are thus typically reconstructed using the most negative sulfate ∆ 17 O value from a given geologic unit (i.e., least overprinted) and scaling by a ∼8% to 15% O2 incorporation factor (7,15). However, anoxic laboratory experiments and modern field observations complicate this picture.…”

mentioning

confidence: 99%

Triple oxygen isotope insight into terrestrial pyrite oxidation

Hemingway

Olson

Turchyn

et al. 2020

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

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The mass-independent minor oxygen isotope compositions (Δ′17O) of atmospheric O2andCO2are primarily regulated by their relative partial pressures,pO2/pCO2. Pyrite oxidation during chemical weathering on land consumesO2and generates sulfate that is carried to the ocean by rivers. The Δ′17O values of marine sulfate deposits have thus been proposed to quantitatively track ancient atmospheric conditions. This proxy assumes directO2incorporation into terrestrial pyrite oxidation-derived sulfate, but a mechanistic understanding of pyrite oxidation—including oxygen sources—in weathering environments remains elusive. To address this issue, we present sulfate source estimates and Δ′17O measurements from modern rivers transecting the Annapurna Himalaya, Nepal. Sulfate in high-elevation headwaters is quantitatively sourced by pyrite oxidation, but resulting Δ′17O values imply no direct troposphericO2incorporation. Rather, our results necessitate incorporation of oxygen atoms from alternative,17O-enriched sources such as reactive oxygen species. Sulfate Δ′17O decreases significantly when moving into warm, low-elevation tributaries draining the same bedrock lithology. We interpret this to reflect overprinting of the pyrite oxidation-derived Δ′17O anomaly by microbial sulfate reduction and reoxidation, consistent with previously described major sulfur and oxygen isotope relationships. The geologic application of sulfate Δ′17O as a proxy for pastpO2/pCO2should consider both 1) alternative oxygen sources during pyrite oxidation and 2) secondary overprinting by microbial recycling.

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“…The disappearance of redox-sensitive detrital minerals, such as pyrite, uraninite and siderite, has long been attributed to the GOE (Holland, 1984(Holland, , 2006Frimmel, 2005;van Kranendonk et al, 2012), although the onset and duration of the GOE is still inadequately constrained (e.g. Luo et al, 2016) and may not have been synchronous everywhere (Phillipot et al, 2018;Hodgskiss et al, 2019). The onset of the GOE is generally considered to have been approximately contemporaneous with what some have interpreted as the Earth's first global scale glaciations (Bekker and Kaufman, 2007;Brasier et al, 2013;Tang and Chen, 2013;Bekker, 2014;Young, 2019).…”

Section: Proterozoic Eon (245/25 To C 0539 Ga)mentioning

confidence: 99%

“…The first macroscopic organic-walled fossils, coiled forms similar to Grypania spiralis, appear within Paleoproterozoic strata by c. 1.89 Ga (Han and Runnegar, 1992;Javaux and Lepot, 2018) to be joined by large, more convincingly eukaryote-grade fossils by the end of the era (Zhu et al, 2016). The Paleoproterozoic fossil record contains the c. 1.88 Ga Gunflint fossil microbes, which are taken to be the oldest unambiguous evidence of iron-oxidising bacteria and oxygenic cyanobacteria (Planavsky et al, 2009;Crosby et al, 2014;Lepot et al, 2017), although cyanobacterial fossils are known also from the c. 2.0 Ga Belcher Group in eastern Hudson Bay (Hofmann, 1975;Hodgskiss et al, 2019).…”

Section: Proterozoic Eon (245/25 To C 0539 Ga)mentioning

confidence: 99%

Towards a new geological time scale: A template for improved rock-based subdivision of pre-Cryogenian time

Shields¹,

Strachan²,

Porter³

et al. 2022

Preprint

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Four first-order (Hadean, Archean, Proterozoic and Phanerozoic eon) and nine second-order (Paleoarchean, Mesoarchean, Neoarchean, Paleoproterozoic, Mesoproterozoic, Neoproterozoic, Paleozoic, Mesozoic and Cenozoic era) units continue to provide intuitive subdivision of geological time. Major transitions in Earth's tectonic, biological and environmental history occurred at approximately 2.5-2.3, 1.8-1.6, 1.0-0.8 and 0.7-0.5 Ga, and so future rock-based subdivision of pre-Cryogenian time, eventually by use of global stratotypes (GSSPs), will likely require only modest deviation from current chronometric boundaries (GSSAs) at 2.5, 1.6 and 1.0 Ga, respectively. Here we argue that removal of GSSAs could be expedited by establishing event-based concepts and provisional, approximate ages for eon-, era-and period-level subdivisions as soon as practicable, in line with ratification of an Ediacaran GSSP in 2004 and chronostratigraphic definition of the Cryogenian Period at c. 720 Ma in 2012. We also outline the geological basis behind current chronometric divisions, explore how they might differ in any future rock-based scheme, identify where major issues might arise during the transition, and outline where some immediate changes to the present scheme could be easily updated/formalised, as a framework for future GSSP development. In line with these aims, we note that the currently recommended four-fold Archean subdivision has not been formally ratified and agree with previous workers that it could be simplified to an informal threefold subdivision, pending more detailed analysis. Although the ages of period boundaries would inevitably change in a more closely rock-based or chronostratigraphic scheme, we support retention of all currently ratified period names. Existing period names, borrowed from the Greek, were chosen to delimit natural phenomena of global reach. Any new global nomenclature ought to follow this lead for consistency, and so we discourage the use of supercontinent names (e.g. Rodinian, Columbian) and regional phenomena, however exceptional. In this regard, we tentatively suggest that a new period (e.g. the 'Kratian'), could precede the Tonian as the first period of the Neoproterozoic Era and we concur with previous authors that the existing Siderian Period (named for banded iron formations) would fit better as a chronostratigraphically defined period of the terminal Archean. Indeed, all pre-Cryogenian subdivisions will need more conceptual grounding in any future chronostratigraphic scheme. We conclude that improved rock-based division of the Proterozoic Eon would likely comprise a threefold , period-level subdivision of the Paleoproterozoic Era (Oxygenian Rhyacian, Orosirian), a four-fold subdivision of the Mesoproterozoic Era (Statherian, Calymmian, Ectasian, Stenian) and potentially four-fold subdivision of the Neoproterozoic Era (pre-Tonian 'Kratian', Tonian, Cryogenian and Ediacaran). Future refinements towards an improved rockbased pre-Cryogenian geological time scale could be propoosed by new interna...

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A productivity collapse to end Earth’s Great Oxidation

Cited by 97 publications

References 55 publications

Carbon isotope evidence for large methane emissions to the Proterozoic atmosphere

Carbon isotope evidence for large methane emissions to the Proterozoic atmosphere

Triple oxygen isotope insight into terrestrial pyrite oxidation

Towards a new geological time scale: A template for improved rock-based subdivision of pre-Cryogenian time

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