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The rise of oxygen in Earth’s early ocean and atmosphere
TLDR
The initial increase of O2 in the atmosphere, its delayed build-up in the ocean, its increase to near-modern levels in the sea and air two billion years later, and its cause-and-effect relationship with life are among the most compelling stories in Earth’s history.
A Whiff of Oxygen Before the Great Oxidation Event?
TLDR
High-resolution chemostratigraphy reveals an episode of enrichment of the redox-sensitive transition metals molybdenum and rhenium in the late Archean Mount McRae Shale in Western Australia, pointing to the presence of small amounts of O2 in the environment more than 50 million years before the start of the Great Oxidation Event.
Tracing the stepwise oxygenation of the Proterozoic ocean
TLDR
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.
Low Mid-Proterozoic atmospheric oxygen levels and the delayed rise of animals
TLDR
Evidence for inhibited oxidation of Cr at Earth’s surface in the mid-Proterozoic is found, suggesting that atmospheric O2 levels were at most 0.1% of present atmospheric levels.
Mo–total organic carbon covariation in modern anoxic marine environments: Implications for analysis of paleoredox and paleohydrographic conditions
[1] Sedimentary molybdenum, [Mo]s, has been widely used as a proxy for benthic redox potential owing to its generally strong enrichment in organic-rich marine facies deposited under oxygen-depleted
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
Low marine sulphate and protracted oxygenation of the Proterozoic biosphere
TLDR
Large stratigraphic variations in the sulphur isotope composition of marine carbonate-associated sulphate are reported, and a rate-dependent model for sulphor isotope change is used that allows us to track changes in marine sulphate concentrations throughout the Proterozoic.
A Stratified Redox Model for the Ediacaran Ocean
TLDR
A detailed spatial and temporal record of Ediacaran ocean chemistry for the Doushantuo Formation in the Nanhua Basin, South China is presented, finding evidence for a metastable zone of euxinic (anoxic and sulfidic) waters impinging on the continental shelf and sandwiched within ferruginous [Fe(II)-enriched] deep waters.
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