Comet Enthusiast

Using novel geochemical techniques developed by Newcastle University’s Dr Simon Poulton, scientists found that beneath oxygenated surface waters, mid-depth oceanic waters were rich in sulphide about 1.8 billion years ago. These  conditions may have persisted until oxygenation of the deep ocean more than one billion years later. These widespread sulphidic conditions close to the continents, coupled with deeper waters that remained oxygen-free and iron-rich, would have placed major restrictions on both the timing and pace of biological evolution.