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Proceedings Paper

Formation of magnetite and iron-rich carbonates by thermophilic iron-reducing bacteria
Author(s): Chuanlun Zhang; Hojatollah Vali; Shi Liu; Yul Roh; Dave Cole; Joseph L. Kirschvink; Tullis C. Onstott; David S. McKay; Tommy James Phelps
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Paper Abstract

Laboratory experiments were performed to study the formation of iron minerals by a thermophilic (45 - 75 degree(s)C) fermentative iron-reducing bacterial culture (TOR39) obtained from the deep subsurface. Using amorphous Fe(III) oxyhydroxide as an electron acceptor and glucose as an electron donor, TOR39 produced magnetite and iron-rich carbonates at conditions consistent, on a thermodynamic basis, with Eh (-200 mV to -415 mV) and pH (6.2 to 7.7) values determined for these experiments. Analyses of the precipitating solid phases by X-ray diffraction showed that the starting amorphous Fe(III) oxyhydroxide was nearly completely converted to magnetite and Fe-rich carbonate after 20 days of incubation. Increasing bicarbonate concentration in the chemical milieu resulted in increased proportions of siderite relative to magnetite and the addition of MgCl2 caused the formation of magnesium-rich carbonate in addition to siderite. The results suggest that the TOR39 bacterial culture may have the capacity to form magnetite and iron-rich carbonates in a variety of geochemical conditions. These results may have significant implications for studying the past biogenic activities in the Martian meteorite ALH84001.

Paper Details

Date Published: 11 July 1997
PDF: 8 pages
Proc. SPIE 3111, Instruments, Methods, and Missions for the Investigation of Extraterrestrial Microorganisms, (11 July 1997); doi: 10.1117/12.278809
Show Author Affiliations
Chuanlun Zhang, Oak Ridge National Lab. (United States)
Hojatollah Vali, McGill Univ. (Canada)
Shi Liu, Oak Ridge National Lab. (United States)
Yul Roh, Oak Ridge National Lab. (United States)
Dave Cole, Oak Ridge National Lab. (United States)
Joseph L. Kirschvink, California Institute of Technology (United States)
Tullis C. Onstott, Princeton Univ. (United States)
David S. McKay, NASA Johnson Space Ctr. (United States)
Tommy James Phelps, Oak Ridge National Lab. (United States)


Published in SPIE Proceedings Vol. 3111:
Instruments, Methods, and Missions for the Investigation of Extraterrestrial Microorganisms
Richard B. Hoover, Editor(s)

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