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Evidence for oxygenic photosynthesis half a billion years before the Great Oxidation Event
The early Earth was characterized by the absence of oxygen in the ocean–atmosphere system, in contrast to the well-oxygenated conditions that prevail today. Atmospheric concentrations first rose to
Proterozoic ocean redox and biogeochemical stasis
This model suggests that the oceanic Mo reservoir is extremely sensitive to perturbations in the extent of sulfidic seafloor and that the record of Mo and chromium enrichments through time is consistent with the possibility of a Mo–N colimited marine biosphere during many periods of Earth’s history.
Oceanic nickel depletion and a methanogen famine before the Great Oxidation Event
A decline in the molar nickel to iron ratio recorded in banded iron formations is reported, which is attributed to a reduced flux of nickel to the oceans, a consequence of cooling upper-mantle temperatures and decreased eruption of nickel-rich ultramafic rocks at the time.
The evolution of the marine phosphate reservoir
There is a peak in phosphorus-to-iron ratios in Neoproterozoic iron formations dating from ∼750 to ∼635 Myr ago, indicating unusually high dissolved phosphate concentrations in the aftermath of widespread, low-latitude ‘snowball Earth’ glaciations.
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.
Was There Really an Archean Phosphate Crisis?
It is shown experimentally that silica effectively competes with phosphate for sorption sites on ferrihydrite particles and reduces particle reactivity toward phosphate, suggesting that Archean oceans probably contained considerably more phosphate than previously predicted.
Benthic perspective on Earth’s oldest evidence for oxygenic photosynthesis
It is numerically demonstrated that local O2 production and immediate consumption in surface-bound (benthic) microbial ecosystems at profound disequilibrium conditions is the most parsimonious explanation for this delay in atmospheric oxygenation, and support the plausible antiquity of a terrestrial biosphere populated by cyanobacteria well before the GOE.