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Pyrite isn’t a reliable proxy for Earth’s oxygenation, study says

Pyrite isn’t a reliable proxy for Earth’s oxygenation, study says

Science
Feb. 26 (UPI) -- When did Earth first acquire large amounts of oxygen? What did the planet's earliest microbial communities look like? Many of the secrets of primordial Earth -- its climate conditions and biochemical composition -- are hidden in layers of marine sediments. To reconstruct Earth's past, scientists rely on certain chemical signatures preserved in the grains of sedimentary rocks. Advertisement Now, new research suggests at least one of those signatures, a mineral called pyrite, is unreliable as a proxy for ancient oxygen levels. Pyrite, an iron sulfide formed in the presence of bacteria, operates as a strong control on oxygen accumulation in Earth's oceans and atmosphere, but it turns out that control is highly localized. According to a new study, published Friday in the jou...