Canfield, Donald E.Poulton, Simon W.Knoll, AndrewNarbonne, Guy M.Ross, GerryGoldberg, TatianaStrauss, Harald2009-07-152008Canfield, Donald E., Simon W. Poulton, Andrew H. Knoll, Guy M. Narbonne, Gerry Ross, Tatiana Goldberg, and Harald Strauss. 2008. Ferruginous conditions dominated later neoproterozoic deep-water chemistry. Science 321(5891): 949-952.0036-80751095-9203http://nrs.harvard.edu/urn-3:HUL.InstRepos:3190372Earth's surface chemical environment has evolved from an early anoxic condition to the oxic state we have today. Transitional between an earlier Proterozoic world with widespread deep- water anoxia and a Phanerozoic world with large oxygen- utilizing animals, the Neoproterozoic Era [1000 to 542 million years ago (Ma)] plays a key role in this history. The details of Neoproterozoic Earth surface oxygenation, however, remain unclear. We report that through much of the later Neoproterozoic (< 742 +/- 6 Ma), anoxia remained widespread beneath the mixed layer of the oceans; deeper water masses were sometimes sulfidic but were mainly Fe(2+)- enriched. These ferruginous conditions marked a return to ocean chemistry not seen for more than one billion years of Earth history.en-US10.1126/science.1154499