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Originally published in Science Express on 17 July 2008
Science 15 August 2008:
Vol. 321. no. 5891, pp. 949 - 952
DOI: 10.1126/science.1154499
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Reports

Ferruginous Conditions Dominated Later Neoproterozoic Deep-Water Chemistry

Donald E. Canfield,1* Simon W. Poulton,2 Andrew H. Knoll,3 Guy M. Narbonne,4 Gerry Ross,5 Tatiana Goldberg,2 Harald Strauss6

Earth'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 Fe2+-enriched. These ferruginous conditions marked a return to ocean chemistry not seen for more than one billion years of Earth history.

1 Nordic Center for Earth Evolution and Institute of Biology, Campusvej 55, University of Southern Denmark, 5230 Odense, Denmark.
2 School of Civil Engineering and Geosciences, Newcastle University, Drummond Building, Newcastle upon Tyne NE1 7RU, UK.
3 Botanical Museum, Harvard University, Cambridge, MA 02138, USA.
4 Department of Geological Sciences and Geological Engineering, Queen's University, Kingston, Ontario K7L 3N6, Canada.
5 Kupa'a Farm, Post Office Box 458, Kula, HI96790, USA.
6 Geologisch-Paläontologisches Institute der Universität Münster, Correnstrasse 24, Münster 48149, Germany.

* To whom correspondence should be addressed. E-mail: dec{at}biology.sdu.dk

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Science. ISSN 0036-8075 (print), 1095-9203 (online)