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Science 2 January 2009:
Vol. 323. no. 5910, pp. 119 - 122
DOI: 10.1126/science.1165373
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Reports

Stretching the Envelope of Past Surface Environments: Neoproterozoic Glacial Lakes from Svalbard

Huiming Bao,1* Ian J. Fairchild,2 Peter M. Wynn,3 Christoph Spötl4

The oxygen isotope composition of terrestrial sulfate is affected measurably by many Earth-surface processes. During the Neoproterozoic, severe "snowball" glaciations would have had an extreme impact on the biosphere and the atmosphere. Here, we report that sulfate extracted from carbonate lenses within a Neoproterozoic glacial diamictite suite from Svalbard, with an age of ~635 million years ago, falls well outside the currently known natural range of triple oxygen isotope compositions and indicates that the atmosphere had either an exceptionally high atmospheric carbon dioxide concentration or an utterly unfamiliar oxygen cycle during deposition of the diamictites.

1 Department of Geology and Geophysics, E235 Howe-Russell Complex, Louisiana State University, Baton Rouge, LA 70803, USA.
2 School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK.
3 Department of Geography, University of Lancaster, Lancaster LA1 4YQ, UK.
4 Institut für Geologie und Paläontologie, Leopold-Franzens-Universität Innsbruck, Innrain 52, 6020 Innsbruck, Austria.

* To whom correspondence should be addressed. E-mail: bao{at}lsu.edu

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