Neoarchaean oxygen-based nitrogen cycle en route to the Great Oxidation Event.

The nitrogen isotopic composition of sedimentary rocks (δN) can trace redox-dependent biological pathways and early Earth oxygenation. However, there is no substantial change in the sedimentary δN record across the Great Oxidation Event about 2.45 billion years ago (Ga), a prominent redox change.

Iron-mediated anaerobic ammonium oxidation recorded in the early Archean ferruginous ocean.

The nitrogen isotopic composition of organic matter is controlled by metabolic activity and redox speciation and has therefore largely been used to uncover the early evolution of life and ocean oxygenation. Specifically, positive δ N values found in well-preserved sedimentary rocks are often interpreted as reflecting the stability of a nitrate pool sustained by water column partial oxygenation. This study adds much-needed data to the sparse Paleoarchean record, providing carbon and nitrogen concentrations and isotopic compositions for more than fifty samples from the 3.

Continental configuration controls ocean oxygenation during the Phanerozoic.

The early evolutionary and much of the extinction history of marine animals is thought to be driven by changes in dissolved oxygen concentrations ([O]) in the ocean. In turn, [O] is widely assumed to be dominated by the geological history of atmospheric oxygen (pO). Here, by contrast, we show by means of a series of Earth system model experiments how continental rearrangement during the Phanerozoic Eon drives profound variations in ocean oxygenation and induces a fundamental decoupling in time between upper-ocean and benthic [O].

The Dziani Dzaha Lake: A long-awaited modern analogue for superheavy pyrites.

Sedimentary records of superheavy pyrites in Phanerozoic and Proterozoic successions (i.e., extremely positive δ S values together with higher δ S than coeval δ S ) are mostly interpreted as resulting either from secondary postdepositional processes or from multiple redox reactions between sulfate and sulfide in stratified sulfate-poor environments.

Author Correction: Constraining the rise of oxygen with oxygen isotopes.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.