Pyrite trace element chemistry of the Velkerri Formation, Roper Group, McArthur Basin: Evidence for atmospheric oxygenation during the Boring Billion

Mukherjee, Indrani; Large, Ross R.

doi:10.1016/j.precamres.2016.05.003

Cited by 59 publications

(29 citation statements)

References 49 publications

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“…As such, these relatively high Mo and U values may mark a transient oxidation event in the ocean–atmosphere system during the mid‐Proterozoic. Importantly, other recent, independent studies of Velkerri trace metal and U isotope data have suggested transient, perhaps global‐scale marine oxygenation for this time period (Mukherjee & Large, ; Yang et al., ).…”

Section: Resultsmentioning

confidence: 67%

“…Iron and trace‐metal data from the Velkerri Formation reveal that there was more apparent temporal variability in the marine redox conditions, at least locally and perhaps globally, during the mid‐Proterozoic than was previously recognized through analysis of the same interval (Kendall et al., ; Mukherjee & Large, ; Shen, Canfield, & Knoll, ; Shen et al., ; Yang et al., ). Overall, the system appears to have evolved from one that was dominantly oxic during deposition of the lower Velkerri Formation to euxinic in the middle Velkerri.…”

Section: Discussionmentioning

confidence: 93%

“…Iron and trace-metal data from the Velkerri Formation reveal that there was more apparent temporal variability in the marine redox conditions, at least locally and perhaps globally, during the mid-Proterozoic than was previously recognized through analysis of the same interval (Kendall et al, 2009;Mukherjee & Large, 2016;Shen, Canfield, & Knoll, 2002;Shen et al, 2003;Yang et al, 2017).…”

Section: Con Clus Ionsmentioning

confidence: 85%

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Absence of biomarker evidence for early eukaryotic life from the Mesoproterozoic Roper Group: Searching across a marine redox gradient in mid‐Proterozoic habitability

et al. 2019

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By about 2.0 billion years ago (Ga), there is evidence for a period best known for its extended, apparent geochemical stability expressed famously in the carbonate–carbon isotope data. Despite the first appearance and early innovation among eukaryotic organisms, this period is also known for a rarity of eukaryotic fossils and an absence of organic biomarker fingerprints for those organisms, suggesting low diversity and relatively small populations compared to the Neoproterozoic era. Nevertheless, the search for diagnostic biomarkers has not been performed with guidance from paleoenvironmental redox constrains from inorganic geochemistry that should reveal the facies that were most likely hospitable to these organisms. Siltstones and shales obtained from drill core of the ca. 1.3–1.4 Ga Roper Group from the McArthur Basin of northern Australia provide one of our best windows into the mid‐Proterozoic redox landscape. The group is well dated and minimally metamorphosed (of oil window maturity), and previous geochemical data suggest a relatively strong connection to the open ocean compared to other mid‐Proterozoic records. Here, we present one of the first integrated investigations of Mesoproterozoic biomarker records performed in parallel with established inorganic redox proxy indicators. Results reveal a temporally variable paleoredox structure through the Velkerri Formation as gauged from iron mineral speciation and trace‐metal geochemistry, vacillating between oxic and anoxic. Our combined lipid biomarker and inorganic geochemical records indicate at least episodic euxinic conditions sustained predominantly below the photic zone during the deposition of organic‐rich shales found in the middle Velkerri Formation. The most striking result is an absence of eukaryotic steranes (4‐desmethylsteranes) and only traces of gammacerane in some samples—despite our search across oxic, as well as anoxic, facies that should favor eukaryotic habitability and in low maturity rocks that allow the preservation of biomarker alkanes. The dearth of Mesoproterozoic eukaryotic sterane biomarkers, even within the more oxic facies, is somewhat surprising but suggests that controls such as the long‐term nutrient balance and other environmental factors may have throttled the abundances and diversity of early eukaryotic life relative to bacteria within marine microbial communities. Given that molecular clocks predict that sterol synthesis evolved early in eukaryotic history, and (bacterial) fossil steroids have been found previously in 1.64 Ga rocks, then a very low environmental abundance of eukaryotes relative to bacteria is our preferred explanation for the lack of regular steranes and only traces of gammacerane in a few samples. It is also possible that early eukaryotes adapted to Mesoproterozoic marine environments did not make abundant steroid lipids or tetrahymanol in their cell membranes.

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Section: Resultsmentioning

confidence: 67%

Section: Discussionmentioning

confidence: 93%

Section: Con Clus Ionsmentioning

confidence: 85%

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Absence of biomarker evidence for early eukaryotic life from the Mesoproterozoic Roper Group: Searching across a marine redox gradient in mid‐Proterozoic habitability

et al. 2019

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“…Redox sensitive trace elements in marine pyrite, including Se, Mo, Sb, U, V and Co have been used as proxies for oxygen levels in the past atmosphere-ocean system (Anbar et al, 2006;Scott et al, 2008;Gill et al, 2009;Sahoo et al, 2012Reinhard et al, 2013;Large et al, 2014Large et al, , 2015Mukherjee and Large, 2016;Gregory et al, 2017). Applied to the Buttington section, the Se/Co ratios in pyrite suggest overall moderate to low atmospheric pO 2 conditions during the early Sheinwoodian ( Fig.…”

Section: Atmospheric Pomentioning

confidence: 99%

Biotic, geochemical and environmental changes through the early Sheinwoodian (Wenlock, Silurian) carbon isotope excursion (ESCIE), Buttington Quarry, Wales

Loydell

Large

2019

Palaeogeography, Palaeoclimatology, Palaeoecology

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“…Conversely, constraints on atmospheric oxygen across this time 100 period vary widely, with recent suggestions of 0.1 to 10% PAL (present atmospheric levels; 101 Cole et al, 2016;Zhang et al, 2016;Daines et al, 2017;Crockford 102 et al, 2018). In addition, while it is tacitly assumed that atmospheric oxygen concentrations 103 remained relatively constant through the mid-Proterozoic (Canfield, 2005;Lyons et al, 2014;104 Planavsky et al, 2014), significant fluctuations in atmospheric oxygen remain a distinct 105 possibility (Diamond et al, 2018;Gilleaudeau et al, 2016;Mukherjee and Large, 2016;Yang 106 et al, 2017;Zhang et al, 2016). Given the close link between atmospheric oxygenation and 107 ocean redox conditions, such fluctuations would naturally be expected to drive significant 108 temporal and, potentially, spatial variability in the ocean's redox structure.…”

Section: Introduction 60mentioning

confidence: 99%

Shallow water anoxia in the Mesoproterozoic ocean: Evidence from the Bashkir Meganticlinorium, Southern Urals

Doyle

Poulton

Newton

et al. 2018

Precambrian Research

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Pyrite trace element chemistry of the Velkerri Formation, Roper Group, McArthur Basin: Evidence for atmospheric oxygenation during the Boring Billion

Cited by 59 publications

References 49 publications

Absence of biomarker evidence for early eukaryotic life from the Mesoproterozoic Roper Group: Searching across a marine redox gradient in mid‐Proterozoic habitability

Absence of biomarker evidence for early eukaryotic life from the Mesoproterozoic Roper Group: Searching across a marine redox gradient in mid‐Proterozoic habitability

Biotic, geochemical and environmental changes through the early Sheinwoodian (Wenlock, Silurian) carbon isotope excursion (ESCIE), Buttington Quarry, Wales

Shallow water anoxia in the Mesoproterozoic ocean: Evidence from the Bashkir Meganticlinorium, Southern Urals

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