Fluctuations in Precambrian atmospheric oxygenation recorded by chromium isotopes

  title={Fluctuations in Precambrian atmospheric oxygenation recorded by chromium isotopes},
  author={Robert Frei and Claudio Gaucher and Simon W. Poulton and Donald E. Canfield},
Geochemical data suggest that oxygenation of the Earth’s atmosphere occurred in two broad steps. The first rise in atmospheric oxygen is thought to have occurred between ∼2.45 and 2.2 Gyr ago, leading to a significant increase in atmospheric oxygen concentrations and concomitant oxygenation of the shallow surface ocean. The second increase in atmospheric oxygen appears to have taken place in distinct stages during the late Neoproterozoic era (∼800–542 Myr ago), ultimately leading to oxygenation… 
A paleosol record of the evolution of Cr redox cycling and evidence for an increase in atmospheric oxygen during the Neoproterozoic
Stable chromium isotope data from multiple paleosols are presented that offer snapshots of Earth surface conditions over the last three billion years and indicate a secular shift in the oxidative capacity of Earth's surface in the Neoproterozoic and suggest low atmospheric oxygen levels through the majority ofEarth's history.
Long-term sedimentary recycling of rare sulphur isotope anomalies
The results can reconcile geochemical evidence for oxygen production and transient accumulation with the maintenance of NMD anomalies on the early Earth, and suggest that future work should investigate the notion that temporally continuous generation of new NMD sulphur isotope anomalies in the atmosphere was likely to have ceased long before their ultimate disappearance from the rock record.
Constraints on Paleoproterozoic atmospheric oxygen levels
This work provides another crucial line of empirical evidence that atmospheric oxygen levels returned to low concentrations following the Lomagundi Event, and remained low enough for large portions of the Proterozoic to have impacted the ecology of the earliest complex organisms.
Oxidative elemental cycling under the low O2 Eoarchean atmosphere
It is suggested that reactive oxygen species were present in the Eoarchean surface environment, under a very low oxygen atmosphere, inducing oxidative elemental cycling during the deposition of the Isua BIFs and possibly supporting early aerobic biology.
Rapid oxygenation of Earth’s atmosphere 2.33 billion years ago
The new data suggest that the oxygenation occurred rapidly—within 1 to 10 million years—and was followed by a slower rise in the ocean sulfate inventory, whereas the relationships among GOE, “Snowball Earth” glaciation, and biogeochemical cycling will require further stratigraphic correlation supported with precise chronologies and paleolatitude reconstructions.
Volcanically modulated pyrite burial and ocean–atmosphere oxidation
Global atmospheric oxygen variations recorded by Th/U systematics of igneous rocks
It is suggested that the secular Th/U evolution of arc igneous rocks could be an effective geochemical indicator recording the global-scale atmospheric oxygen variation.
Aerobic bacterial pyrite oxidation and acid rock drainage during the Great Oxidation Event
An independent and complementary record of marine Cr supply is provided, in the form of Cr concentrations and authigenic enrichment in iron-rich sedimentary rocks, to add to amassing evidence that the Archaean-Palaeoproterozoic boundary was marked by a substantial shift in terrestrial geochemistry and biology.


Tracing the stepwise oxygenation of the Proterozoic ocean
A new perspective on ocean oxygenation is presented based on the authigenic accumulation of the redox-sensitive transition element molybdenum in sulphidic black shales, which reflects a greatly expanded oceanic reservoir due to oxygenation of the deep ocean and corresponding decrease in sulphide conditions in the sediments and water column.
Dating the rise of atmospheric oxygen
It is found that syngenetic pyrite is present in organic-rich shales of the 2.32-Gyr-old Rooihoogte and Timeball Hill formations, South Africa, indicating that atmospheric oxygen was present at significant levels during the deposition of these units.
A new model for Proterozoic ocean chemistry
There was a significant oxidation of the Earth's surface around 2 billion years ago (2 Gyr). Direct evidence for this oxidation comes, mostly, from geological records of the redox-sensitive elements
The transition to a sulphidic ocean ∼ 1.84 billion years ago
The Proterozoic aeon (2.5 to 0.54 billion years (Gyr) ago) marks the time between the largely anoxic world of the Archean (> 2.5 Gyr ago) and the dominantly oxic world of the Phanerozoic (< 0.54 Gyr
Late Archean Biospheric Oxygenation and Atmospheric Evolution
The correlation of the time-series sulfur isotope signals in northwestern Australia with equivalent strata from South Africa suggests that changes in the exogenic sulfur cycle recorded in marine sediments were global in scope and were linked to atmospheric evolution.
Iron Isotope Constraints on the Archean and Paleoproterozoic Ocean Redox State
Variable and negative iron isotope values in pyrites older than about 2.3 Ga suggest that an iron-rich global ocean was strongly affected by the deposition of iron oxides in a redox stratified ocean.
■ Abstract This paper reviews the Precambrian history of atmospheric oxygen, beginning with a brief discussion of the possible nature and magnitude of life before the evolution of oxygenic
▪ Abstract This paper reviews the Precambrian history of atmospheric oxygen, beginning with a brief discussion of the possible nature and magnitude of life before the evolution of oxygenic