Deposition of banded iron formations by anoxygenic phototrophic Fe(II)-oxidizing bacteria
- 1 California Institute of Technology, GPS Division, Pasadena, California 91125, USA
- 2Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada
- 3California Institute of Technology, GPS Division, Pasadena, California 91125, USA
Abstract
The mechanism of banded iron formation (BIF) deposition is controversial, but classically has been interpreted to reflect ferrous iron [Fe(II)] oxidation by molecular oxygen after cyanobacteria evolved on Earth. Anoxygenic photoautotrophic bacteria can also catalyze Fe(II) oxidation under anoxic conditions. Calculations based on experimentally determined Fe(II) oxidation rates by these organisms under light regimes representative of ocean water at depths of a few hundred meters suggest that, even in the presence of cyanobacteria, anoxygenic phototrophs living beneath a wind-mixed surface layer provide the most likely explanation for BIF deposition in a stratified ancient ocean and the absence of Fe in Precambrian surface waters.
Footnotes
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↵*Present address: Center for Applied Geoscience, University of Tübingen, 72074 Tübingen, Germany
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↵GSA Data Repository item 2005170, isolation and identification of pigments, is available online at www.geosociety.org/pubs/ft2005.htm, or on request from editing{at}geosociety.org or Documents Secretary, GSA, P.O. Box 9140, Boulder, CO 80301, USA.
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- Accepted 28 June 2005.
- Received 25 February 2005.
- Revision received 21 June 2005.
- Geological Society of America
