Biomarker evidence for green and purple sulphur bacteria in a stratified Palaeoproterozoic sea

  title={Biomarker evidence for green and purple sulphur bacteria in a stratified Palaeoproterozoic sea},
  author={Jochen J. Brocks and Gordon D. Love and Roger Everett Summons and Andrew H. Knoll and Graham A. Logan and Stephen A. Bowden},
The disappearance of iron formations from the geological record ∼1.8 billion years (Gyr) ago was the consequence of rising oxygen levels in the atmosphere starting 2.45–2.32 Gyr ago. It marks the end of a 2.5-Gyr period dominated by anoxic and iron-rich deep oceans. However, despite rising oxygen levels and a concomitant increase in marine sulphate concentration, related to enhanced sulphide oxidation during continental weathering, the chemistry of the oceans in the following mid-Proterozoic… 
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